(A. J* \j 'The most perfect system of rules to insure success must be interpreted upon the broad grounds of professional intelli- gence and common sense." GENERAL SPECIFICATIONS FOR Iron and Steel Railroad Bridges AND VIADUCTS. NEW AND REVISED EDITION, 189O. By THEODORE COOPER, Consulting Engineer. ENGINEERING NEWS PUBLISHING COMPANY, TRIBUNE BUILDING, NEW YORK. OF THE AMERICAN RAILROAD BRIDGES, By THEODORE COOPER, M. Am. Soe. C. E., Reprinted from the Transactions of American Society of Civil Engineers . PRICE. 60 pages, 8vo., cloth. 18 Folding Plates; 8 page illustrations by Phototype process; Appendix giving Abstract of Recent Tests on full size Bridge Members, - - $2 OO Specifications for Iron and Steel Railroad Bridges, $O 25 Highway " 25 ENGINEERING NEWS PUBLISHING COMPANY, Tribune Building, New York. UN, Copyright by THEODORE COOPER, Consulting Engineer, 35 Broadway, New York. General Specifications for Iron and Steel Railroad Bridges and Viaducts, NEW AND REVISED EDITION. 1890. GENERAL DESCRIPTION. 1. All parts of the structures shall be of wrought-iron or steel, except ties and guard rails. Cast-iron or steel may be used in the machinery of movable bridges and in special cases for bed-plates. 2. The following kinds of girders shall preferably be em- ployed : Spans, up to 16 feet Boiled beams. Bridges. " 16 to 70 " Riveted plate girders. " 70 to 100 " Riveted plates or lattice girders. " over loo " Pin-connected trusses. Generally "double tracks through'' bridges will have but two trusses, to avoid spreading the tracks at bridges. In calculating strains the length of span shall be under- Length of spau. stood to be the distance between centres of end pins for trusses, and between centres of bearing plates for all beams and girders. 3. The girders shall be spaced, with reference to the axis gpjSjJJg of of the bridge, as required by local circumstances, and directed by the Engineer of the Railroad Company. ( 5.) Longitudinal floor girders shall in no case be less than three feet and three inches from centre line of tracks. ( 6.) 4. For all through bridges and overhead structures there Head-room, shall be a clear head-room of 20 feet above the base of the rails. 5. In all through bridges the clear width from the centre ciear width, of the track to any part of the trusses shall not be less than seven (7) feet at a height exceeding one foot above the rails where the tracks are straight, and an equivalent clearance shall be provided where the tracks are curved. 6. The standard distance, centre to centre of tracks on straight lines, will be thirteen (13) feet. Treetie Towers. ^ Each trestle bent shall, as a general rule, be composed of two supporting columns, and the bents united in pairs to form towers ; each tower thus formed of four columns shall be thoroughly braced in both directions. Transversely the column shall have a uniform batter sufficient to nearly or quite prevent tension at the base under the greatest wind force specified, either during erection or after completion. 8. Each tower shall have sufficient base, longitudinally, to be stable when standing alone, without other support than its anchorage. ( 25, 26.) Trestle spans. 9> Tower spans for high trestles shall not be less than 30 feet ; intermediate spans about 60 feet. Form of Trusses lOf Unless otherwise specified the form of bridge trusses may be selected by the bidder ; but to secure uniformity in appearance it is desired that all " through " trusses shall be built with inclined end posts ; for pin-connected trusses, preference shall be given to those of single intersections. ii. All "deck" trusses shall have top chord bearings at abutments, which are retaining walls, unless otherwise or- dered for particular structures. wooden rioor. I2 x ne WO oden floors shall consist of transverse ties or floor timbers ; their scantling will vary in accordance with the design of the supporting iron floor. ( 15.) They shall be spaced with openings not exceeding six inches, and shall be secured to the supporting girders by |-inch bolts at dis- tances not over six feet apart. For deck bridges the ties will extend the full width of the bridge, and for through bridges at least every other tie shall extend the full width of bridge for a footwalk. Guard Timbers. 1$. There shall be a guard timber (scantling not less than 6 x 8") on each side of each track, with its inner face parallel to and not less than 3 feet 3 inches from centre of track. Guard timbers must be notched one inch over every floor timber, and be spliced over a floor timber with a half-and- 3 half joint of four inches lap. Each guard timber shall be fastened to every third floor timber and at each splice with a three-quarter (f ) inch bolt. 14. The guard and floor timbers must be continued over all piers and abutments. 15. The maximum strain allowed upon the extreme fibre of the best yellow pine or white oak floor timbers will be 800 pounds per square inch. The weight of a single engine wheel being assumed as distributed over three ties spaced as per 12. 1 6. The floor timbers from centre to each end of span must be notched down over longitudinal girders so as to reduce the camber in the track, as directed by the Engineer. 17. All the floor timbers shall have a full and even bear- ing upon the stringers; no open joints or shims will be allowed. 1 8. On curves the outer rail must be elevated, as may be directed by the Engineer. 19. In comparing different proposals, the relative cost to pr p 8als - the Railroad Company of the required masonry or changes in existing work will be taken into consideration. 20. Contractors in submitting proposals shall furnish complete strain sheets, general plans of the proposed structures, and such detail drawings as will clearly show the dimensions of all the parts, modes of construction, and the sectional areas. 21. Upon the acceptance of the proposal and the execu- tion of contract, all working drawings required by the Engineer must be furnished free of cost. 22. No work shall be commenced or materials ordered Approval of until the working drawings are approved by the Engineer in writing; if such working drawings are detained more than one week for examination, the Contractor will be allowed an equivalent extension of time. LOADS. 23. All the structures shall be proportioned to carry the following loads : ist. The weight of iron in the structure. 2d. A floor weighing 400 pounds per linear foot of track, to consist of rails, ties, and guard timbers only. These two items, taken together, shall constitute the "dead load." 3d. For class Lehigh Heavy Grade Engine A moving load for each track, supposed to be moving in either direc- tion, and consisting of two " consolidation '' engines coupled, followed by train weighing 4,000 pounds per run- ning foot. This "live load" being concentrated upon points distributed as in Diagram No. i. Or, 100,000 pounds equally distributed upon two pairs of drivers, seven feet centre to centre ; or, 3d. For class Extra Heavy A A moving load for each track, supposed to be moving in either direction, and con- sisting of two " consolidation " engines coupled, followed by train weighing 3,000 pounds per running foot. This " live load " being concentrated upon points distributed as in Diagram No. 2. Or, 80,000 pounds equally distributed upon two pairs of drivers, seven feet centre to centre ; or, 3d. For class A A moving load for each track, supposed to be moving in either direction, and consisting of two ' ' consolidation " engines coupled, followed by train weigh- ing 3,000 pounds per running foot. This " live load " being concentrated upon points distributed as in Diagram No. 3. Or, 80,000 pounds equally distributed upon two pairs of drivers, seven feet centre to centre ; or, 3d. For class B A moving load for each track, supposed to be moving in either direction, and consisting of two " consolidation " engines coupled, followed by train weigh- ing 2,240 pounds per running foot. This " live load " being concentrated upon points distributed as in Diagram No. 4. Or, 80,000 pounds equally distributed upon two pairs of drivers, seven feet six inches centre to centre ; or, 3d. For class C A moving load for each track, supposed to be moving in either direction, and consisting of two " mogul '' engines coupled, followed by train weighing 2,000 pounds per running foot. This " live load " being concentrated upon points distributed as in Diagram No. 5. Or, 80,000 pounds equally distributed upon two pairs of drivers, eight feet centre to centre. Diagram No. 1. Diagram No. 2. Diagram No. 3. Diagram No. 4 Diagram No. 5. o*i s* CO*** 1 jg 1* _ 20000 20000 180CO 18000 40000 40000 40000 40000 16000 20000 20000 18000 18000 40000 40000 18000 18000 18000 18000 30000 30000 30000 < 30000 f 16000 2 "jj 18000 ^ 18000 ^ 18000 18000 30000 30000 30000 30000 16000 15000 15000 15000 15000 24000 24000 24000 24000 15COO as 15000 15000 15000 15000 24000 24000 24000 24000 15000 14500 14500 14500 14500 22000 22000- 22000 22000 15000 M 3, 14500 14500 14500 14500 22000 22000 22000 22000 15000 1 ; ,n < 13500 13500 13500 13500 25000 25000 25000 15000 13500 13500 13500 13500 25000 25000 25000 15000 1 ^ 1 r J 1 -e ^ * 1 tl Jj e. e i ^^^^ , Ir w ih ft* -e \o 1 j zj 6> 51 6! ' 1 Is J S ] -e e 0) J i' 1C X e e e u >< i in 40000 * =a ^ 16000 IN 6 The maximum strains due to all positions of either of the above "live loads," of the required class, and of the " dead load," shall be taken to proportion all the parts of the struc- ture. 24. To provide for wind strains and vibrations, the top lateral bracing in deck bridges, and the bottom lateral brac- ing in through bridges, shall be proportioned to resist a lateral force of 450 pounds for each foot of the span ; 300 pounds of this to be treated as a moving load. The bottom lateral bracing in deck bridges, and the top lateral bracing in through bridges, shall be proportioned to resist a lateral force of 1 50 pounds for each foot of the span. Preference will be given to lateral bracing in the floor system, which is capable of resisting both compression and tension. 25. In trestle towers the bracing and columns shall be proportioned to resist the following lateral pressures, in addition to the strains from dead and live loads : ist. The trusses fully loaded, a lateral pressure at the level of the tracks, of 650 pounds for each longitudinal lineal foot of the structure; and a lateral pressure of 125 pounds for each vertical lineal foot of the trestle bents ; or, 2d. The trusses unloaded, a lateral pressure, at the level of the tracks, of 600 pounds for each longitudinal lineal foot of the structure ; and a lateral pressure of 225 pounds for each vertical lineal foot of the trestle bents. 26. Longitudinally the bracing of the trestle towers and the attachments of the fixed ends of all trusses shall be capable of resisting the greatest tractive force of the engines, or any force induced by suddenly stopping upon any part of the work the assumed maximum trains ; the co- efficient of friction of the wheels upon the rails being as- sumed as 0.20. 27. Variations in temperature, to the extent of 150 de- grees, shall be provided for. 28. When the structures are on curves, the additional effects due to the centrifugal force of trains moving at high velocities shall be considered. 29. All parts shall be so designed that the strains coming upon them can be accurately calculated. PROPORTION OF PARTS. The following clauses are all intended to apply to wrought- iron construction. 30. All parts of the structure shall be proportioned in Tensile strain, tension by the following allowed unit strains : Pounds per square inch. Floor beam hangers, and other similar members liable to sudden loading (bar iron with forged ends) _ 6,000 Floor beam hangers, and other similar members liable to sudden loading (plates or shapes), net section $ ,000 Lateral bracing __ 15 ,000 Solid rolled beams, used as cross floor beams and stringers 8,000 Bottom flanges of riveted cross girders, net section 8,000 Bottom flanges of riveted longitudinal plate gird- ers, over 20 feet long, used as track stringers, net section _. 8,000 Bottom flanges of riveted longitudinal plate gir- ders, under 20 feet 1 ong, net section _ 7,000 For For live loads. dead loads. Bottom chords, main diagonals, counters and long verticals (forged eye-bars) 8,000 16,000 Bottom chords and flanges, main diago- nals, counters and long verticals (plates or shapes), net section 7>5oo 1 5,000 For swing bridges and other movable structures, the dead load unit strains, during motion, must not exceed three- fourths of the above allowed unit strains for dead load on stationary structures. The areas obtained by dividing the live load strains by the live load unit strains will be added to the areas ob- tained by dividing the dead load strains by the dead load Net Section. Compressive Strains. 8 unit strains to determine the required sectional area of any member. ( 45.) 31. Angles subject to direct tension must be connected by both legs, or the section of one leg only will be con- sidered as effective. 32. In members subject to tensile strains full allowance shall be made for reduction of section by rivet-holes, screw- threads, etc. 33. Compression members shall be proportioned by the following allowed unit strains : Chord segments P= 8,000 30 for live load strains. Struts. All posts P= 1 6,000 60 for dead load strains. P=7,ooo 40 for live load strains. 14,000 80 for dead load strains. 10,50060 for wind strains. r P=9,ooo 50 for assumed initial strain. Lateral struts ( 340 P=the allowed compression per square inch of cross- section. Z=the length of compression member, in inches. R=ihe least radius of gyration of the section, in inches. No compression member, however, shall have a length exceeding 45 times its least width. For swing bridges and other movable structures, the dead load unit strains during motion must not exceed J of the above allowed unit strains for dead load on stationary structures. 34. The lateral struts shall be proportioned by the above formula ( 33) to resist only the resultant due to an assumed initial strain of 10,000 pounds per square inch upon all the rods attaching to them, assumed to be produced by adjusting the bridge or towers. ( 41.) 9 35- In beams and plate girders the compression shall be made of same gross section as the tension flanges. 36. Riveted longitudinal girders shall have, preferably, a depth not less than T \ of the span. Rolled beams used as longitudinal girders shall have, pre- ferably, a depth not less than y 1 ^ of the span. 37. Members subject to alternate strains of tension and compression shall be proportioned to resist each kind of strain. Both of the strains shall, however, be considered as increased by an amount equal to -f^ of the least of the two strains, for determining the sectional areas by the above allowed unit strains. ( 30, 33.) 38. The strains in the chords and end posts from the as- Effectofwind on Chord sumed wind forces need not be considered, except as strains - follows : ist. When the wind strains on any member exceed one- quarter of the maximum strains due to the dead and live loads upon the same member. The section shall then be increased until the total strain per square inch will not exceed by more than one-quarter the maximum fixed for dead and live loads only. 2d. When the wind strain alone or in combination with a possible temperature strain, can neutralize or reverse the tension in any part of the lower chord. 39. The rivets and bolts connecting the parts of any mem- Rivets, Bolts ber must be so spaced that the shearing strain per square" 1 inch shall not exceed 7,500 pounds, or f of the allowed strain per square inch upon that member; nor the pressure upon the bearing surface per square inch of the projected semi- intrados (diameter X thickness of piece) of the rivet or bolt hole exceed 12,000 pounds, or one and a half times the allowed strain per square inch upon that member. In the case of field riveting the above limits of shearing strain and pressure shall be reduced one-third part. Rivets must not be used in direct tension. 40. Pins shall be so proportioned that the shearing strain shall not exceed 7,500 pounds per square inch; nor the crush- ing strain upon the projected area of the semi-intrados of any member (other than forged eye-bars, see article 79) con- 10 Combined Strains. Plate Girders, etc. Web Plates. Boiled Beams. nected to the pin be greater per square inch than 12,000 pounds, or one and a half times the allowed strain per square inch ; nor the bending strain exceed 15,000 pounds per square inch when the centres of bearings of the strained members are taken as the points of application of the strains. 41. In case any member is subjected to a bending strain from local loadings, such as distributed floors on deck bridges, in addition to the strain produced by its position as a member of the structure, it must be proportioned to resist the combined strains. If the fibre strain resulting from the weight only, of any member, exceeds ten per cent, of the allowed unit strain on such member, such excess must be considered in propor- tioning the areas. 42. Plate girders shall be proportioned upon the suppo- sition that the bending or chord strains are resisted entirely by the upper and lower flanges, and that the shearing or web strains are resisted entirely by the web-plate ; no part of the web-plate shall be estimated as flange area. The distance between centres of gravity of the flange areas will be considered as the effective depth of all girders. 43. The webs of plate girders must be stiffened at in- tervals, about the depth of the girders, wherever the shear- ing strain per square inch exceeds the strain allowed by the following formula : 12 OOO Allowed shearing strain = ' i + 3,000 where H = ratio of depth of web to its thickness; but no web-plates shall be less than three-eighths of inch in thick- ness. 44. Rolled beams shall be proportioned ( 30, 35) by their moments of inertia. 45. The areas of counter rods shall be determined by taking the difference in areas due to the live and dead load strains considered separately ( 30); the counter rods in any one panel must have a combined sectional area of at least three square inches, or else must be capable of carry- ing all the counter live load in that panel. 11 DETAILS OF CONSTRUCTION. 46. All the connections and details of the several parts of Details, the structures shall be of such strength that, upon testing, ruptures shall occur in the body of the members rather than in any of their details or connections. 47. Preference will be had for such details as shall be most accessible for inspection, cleaning and painting ; no closed sections will be allowed. 48. The webs of plate girders must be spliced at all joints webspiices. by a 'plate on each side of the web. 49. All web-plates must have stiffeners over bearing stiffeners. points and at points of local concentrated loadings. 50. The pitch of rivets in all classes of work shall never Riveting, exceed 6 inches, or sixteen times the thinnest outside plate, nor be less than three diameters of the rivet. 51. The rivets used shall generally be and | inch dia- meter. 52. The distance between the edge of any piece and the centre of a rivet-hole must never be less than i inches, except for bars less than 2\ inches wide; when practicable it shall be at least two diameters of the rivet. 53. In punching plate or other iron, the diameter of the die shall in no case exceed the diameter of the punch by more than T \ of an inch, and all holes must be clean cuts without torn or ragged edges. 54. All rivet-holes must be so accurately spaced and punched that when the several parts forming one member are assembled together, a rivet T V inch less in diameter than the hole can generally be entered, hot, into any hole, with- out reaming or straining the iron by " drifts ;" occasional variations must be corrected by reaming. 55. The rivets when driven must completely fill the holes. The rivet-heads must be round and of a uniform size for the same sized rivets throughout the work. They must be full and neatly made, and be concentric to the rivet-hole, and thoroughly pinch the connected pieces together. 56. Wherever possible, all rivets must be machine driven. The machines must be capable of retaining the applied pres- 12 Bolts. Splices. sure after the upsetting is completed. No hand-driven rivets exceeding | inch diameter will be allowed. 57. Field riveting must be reduced to a minimum or entirely avoided, where possible. 58. The effective diameter of a driven rivet will be as- sumed the same as its diameter before driving. In deduct- ing the rivet-holes to obtain net sections in tension mem- bers, the diameter of the rivet-hole will be assumed as -J- inch larger than the undriven rivets. 59. When members are connected by bolts which trans- mit shearing strains, the holes must be reamed parallel and the bolts turned to a driving fit. 60. The several pieces forming one built member must fit closely together, and when riveted shall be free from twists, bends or open joints. 61. All joints in riveted tension members must be fully and symmetrically spliced. Abutting joints, fo j n compression members, abutting joints with planed faces must be sufficiently spliced to maintain the parts ac- curately in contact against all tendencies to displacement. 63. In compression members, abutting joints with un- tooled faces must be fully spliced, as no reliance will be placed on such abutting joints. The abutting ends must, however, be dressed straight and true, so there will be no open joints. 64. All the angles, filling and splice plates on the webs of girders and riveted members must fit at their ends to the flange angles, sufficiently close to be sealed when painted, against admission of water; but need not be tool finished. web piates. 65. Web-plates of all girders must be arranged so as not to project beyond the faces of the flange angles, nor on the top be more than T ^ inch below the face of these angles, at any point. 66. Wherever there is a tendency for water to collect, the spaces must be filled with a suitable waterproof material. nange piates. 67. In girders with flange plates, at least one-half of the flange section shall be angles or else the largest sized angles must be used. 13 68. In lattice girders, the web members must be double and connect symmetrically to the web of the flanges. 69. The compression flanges of beams and girders shall be stayed against transverse crippling when their length is more than thirty times their width. 70. The unsupported width of plates subjected to com- pression shall not exceed thirty times their thickness ; except cover plates of top chords and end posts, which will be limited to forty times their thickness. 71. The flange plates of all girders must be limited in width so as not to extend beyond the outer lines of rivets connecting them with the angles, more than five inches or more than eight times the thickness of the first plate. Where two or more plates are used on the flanges, they shall either be of equal thickness or shall decrease in thickness outward from the angles. 72. No iron shall be used less than inch thick, except for lining or filling vacant spaces. 73. The heads of eye-bars shall be so proportioned and Eye Bar8 ' made, that the bars will preferably break in the body of the original bar rather than at any part of the head or neck. The form of the head and the mode of manufacture shall be subject to the approval of the Engineer of the Railroad Company. The heads must be formed either by the process of upsetting and forging, or by the process of upsetting, piling and forging. No welding will be allowed in the body of the bars, nor in the process of piling, welding seams in any other direction than parallel to the sides of the original bars. 74. The bars must be free from flaws and of full thick- ness in the necks. They shall be perfectly straight before boring. The holes shall be in the centre of the head, and on the centre line of the bar. 75. The bars must be bored to lengths not varying from the calculated lengths more than ^ of an inch for each 25 feet of total length. 76. Bars which are to be placed side by side in the structure shall be bored at the same temperature and of such equal length that upon being piled on each other the *& OF THE UNIVERSITY u pins shall pass through the holes at both ends without driving. 77. The lower chord shall be packed as narrow as possible. 78. The pins shall be turned straight and smooth, and shall fit the pin-holes within ^ of an inch, for pins less than 4^ inches diameter ; for pins of a larger diameter the clear- ance may be -fa inch. 79. The diameter of the pin shall not be less than two- thirds the largest dimension of any tension member at- tached to it. The several members attaching to the pin shall be so packed as to produce the least bending moment upon the pin, and all vacant spaces must be filled with wrought-iron filling rings. 80. All rods and hangers with screw ends shall be upset at the ends, so that the diameter at the bottom of the threads shall be y 1 ^ inch larger than any part of the body of the bar. 81. All threads must be of the United States standard, except at the ends of the pins. 82. Floor beam hangers shall be so placed that they can be readily examined at all times. When fitted with screw ends they shall be provided with check nuts. Preference will be given to hangers without screw ends. 83. When bent loops are used, they must fit perfectly around the pin throughout its semi-circumference. 84. All nuts on floor beam hangers and counter rods must have the bearing faces faced square to the axes of the screw ends. 85. Compression members shall be of wrought-iron, and of approved forms. 86. The pitch of rivets at the ends of compression mem- bers shall not exceed four diameters of the rivets for a length equal to twice the width of the member. 87. The open sides of all compression members shall be stayed by batten plates at the ends and diagonal lattice- work at intermediate points. The batten plates must be placed as near the ends as practicable, and shall have a length of ij times the width of the member. The size and 15 spacing of the lattice bars shall be duly proportioned to the size of the member. They must not be less than 2 X i inches for posts 6 inches wide, nor 4X1 inches for posts 15 inches wide. They shall be inclined at an angle not less than 60 to the axis of the member. The pitch of the latticing must not exceed the width of the channel plus nine inches. 88. Where necessary, pin-holes shall be reinforced by plates, so the allowed pressure on the pins shall not be exceeded. These reinforcing plates must contain enough rivets to transfer their proportion of the bearing pressure, and at least one plate on each side shall extend not less than six inches beyond the edge of the batten plates. ( 87.) 89. Where the ends of compression members are forked to connect to the pins, the aggregate compressive strength of these forked ends must equal the compressive strength of the body of the members ; in order to insure this result the aggregate sectional area of the forked ends, at any point between the inside edge of the pin-hole and six inches be- yond the edge of the batten plate, shall be about double that of the body of the member. 90. In compression chord sections, the material must mostly be concentrated at the sides, in the angles and vertical webs. Not more than one plate, and this not exceeding inch in thickness, shall be used as a cover plate, except when neces- sary to resist bending strains. ( 41.) 91. The sections of compression chords shall be con-TopOhord nected at the abutting ends by splices sufficient to hold them Sp truly in position. 92. The ends of all square-ended members shall be planed smooth, and exactly square to the centre line of strain. 93. All members must be free from twists or bends. Por- tions exposed to view shall be neatly finished. 94. Pin-holes shall be bored exactly perpendicular to a vertical plane passing through the centre line of each mem- ber, when placed in a position similar to that it is to occupy in the finished structure. 95. Abutting joints in truss bridges shall be in exact con- Abutting joints, tact throughout. 16 Transverse Diagonal Braciug. Lateral Bracing. 96. In no case shall any lateral or diagonal rod have a less area than J of a square inch. 97. The attachment of the lateral system to the chords shall be thoroughly efficient. If connected to suspended floor beams, the latter shall be stayed against all motion. 98. Preference will be given for a stiff angle iron lateral system between the chords on the level of the floor. 99. All through bridges with top lateral bracing shall have wrought-iron latticed portals, of approved design, at each end of the span, connected rigidly to the end posts. They shall be as deep as the specified head-room will allow. ( 38.) 100. When the height of the trusses exceed 25 feet, an approved system of overhead diagonal bracings shall be at- tached to each post and to the top lateral struts. 101. Pony trusses and through plate or lattice girders shall be stayed by knee braces or gusset plates attached to the top chords at the ends, and at intermediate points, not more than 10 feet or a panel length apart, and attached below to the cross floor beams or to the transverse struts. 102. All deck girders shall have transverse braces at the end. All deck bridges shall have transverse bracing at each panel point. This bracing shall be proportioned to resist the unequal loading of the trusses. The transverse bracing at the ends shall be of the same equivalent strength as the end top lateral bracing. 103. All bed-plates must be of such dimensions that the greatest pressure upon the masonry shall not exceed 250 pounds per square inch. Friction Boilers 104. All bridges over 75 feet span shall have at one end nests of turned friction rollers, formed of wrought-iron or steel, running between planed surfaces. The rollers shall not be less than 2 inches diameter, and shall be so pro- portioned that the pressure per lineal inch of rollers shall not exceed the product of the square root of the diameter of the roller in inches multiplied by 500 pounds, ($oo\/ d.)- 105. Bridges less than 75 feet span shall be secured at one end to the masonry, and the other end shall be free to move upon planed surfaces. Bed Plates. 17 106. Where two spans rest upon the same masonry, a continuous wrought-iron plate, not less than f-inch thick, shall extend under the two adjacent bearings. 107. All the bed-plates and bearings under fixed and mov- able ends must be fox-bolted to the masonry ; for trusses, these bolts must not be less than ij inches diameter; for plate and other girders, not less than |-inch diameter. The contractor must furnish all bolts, drill all holes, and set bolts to place with sulphur. 108. While the roller ends of all trusses must be free to move longitudinally under changes of temperature, they shall be anchored against lifting or moving sideways. 109. All iron bridges with parallel chords shall be given a amber - camber by making the panel lengths of the top chord longer than those of the bottom chord, in the proportion of -J of an inch to every ten feet. no. All bolts must be of neat lengths, and shall have aBoits. washer under the heads and nuts where in contact with wood. in. The lower struts in trestle towers shall be securely anchored to intermediate masonry piers when the magnitude of the structure, in the opinion of the Engineer, requires it ; these struts shall always have ample stiffness to move the tower columns under the effects of changes of temperature, and prevent the slacking of the diagonal brace rods. 112. Tower footings and bed-plates must be planed on all Bed piate sliding surfaces ; and the holes for anchor bolts slotted to allow for the proper amount of movement. ( 27.) 113. All joints in the tower columns shall be fully spliced for all possible tension strains, and to hold the parts firmly in position. 114. The connection of all the diagonal tension members with the columns shall, preferably, be made by means of pins passing through the column's axis. 115. The tension diagonals shall be adjustable, but must have check nuts at all adjustable points ; and shall be sup- ported and clamped at suitable intervals to prevent sagging and rattling. 18 workmanship. Il6 ^]] workmanship shall be first-class in every par- ticular. 1 17. Whenever necessary for the protection of the thread, provision shall be made for the use of pilot nuts in erection. USE OF STEEL. Medium steei. jjg. Medium steel ( 139) may be used for tension mem- bers, plate girders, rolled beams and top chord sections with an allowance of 20 percent, increase above allowed working strains on wrought-iron ; and for all posts by use of the fol- lowing formulas, in place of those given for wrought-iron (33): p= 8,500 55 for live load strains. P=* 1 7,000 i io " dead " r p=i 3,000 85 " wind " Provided that, in addition to the previous details of con- struction, 1 19. All sheared edges of plates and angles be planed off to a depth of one-quarter of an inch. All punched holes be reamed to a diameter of |-inch larger, so as to remove all the sheared surface of the metal. 120. No sharp or unfilleted re-entrant corners be allowed. 121. All rivets to be of steel. 122. Any piece which has been partially heated or bent cold, be afterwards wholly annealed. soft steei. I2 3- Soft steel ( 141) may be used under the same condi- tions as wrought-iron for all riveted work. Provided, that 124. Any rivet hole punched, as in ordinary practice ( 52 and 53), will stand drifting to a diameter 25 per cent, greater than the original hole without cracking, either in the periphery of the hole or on the external edges of the piece, whether they be sheared or rolled. ID QUALITY OF MATERIAL. IRON. 125. All wrought-iron must be tough, fibrous and uniform Iron - in character. It shall have a limit of elasticity of not less than 26,000 pounds per square inch. Finished bars must be thoroughly welded during the roll- ing, and be free from injurious seams, blisters, buckles, cinder spots, or imperfect edges : all iron for eye-bars or other forgings and for bent plates, must be capable of being worked at a proper heat without injury. 126. For all tension members high test bars must be used, Tension Tests, capable of standing the following tests : 127. Full sized pieces of flat, round or square iron, not over 4i inches in sectional area, shall have an ultimate strength of 50,000 pounds per square inch, and stretch \2\ per cent, in the whole length of the body of the bars. Bars of a larger sectional area than 4^ square inches will be allowed a reduction of 1,000 pounds per square inch for each additional square inch of section, down to a minimum of 46,000 pounds per square inch, and 10 per cent, stretch in the whole length of the body of the bars. 128. When tested in specimens of uniform sectional area of at least \ square inch for a distance of 10 inches, taken from tension members which have been rolled to a section not more than 4^ square inches, the iron shall show an ulti- mate strength o( 52,000 pounds per square inch, and stretch 1 8 per cent, in a distance of 8 inches. Specimens taken from bars of a larger cross-section than 4^ inches will be allowed a reduction of 500 pounds for each additional square inch of section, down to a minimum of 48,000 pounds, and 15 per cent, stretch. 129. The same sized specimens taken from angle and other shaped iron shall have an ultimate strength of 48,000 pounds per square inch, and elongate 15 per cent, in 8 inches. 130. The same sized specimens taken from plates less than 24 inches in width, shall have an ultimate strength of 48,000 pounds, and elongate 15 per cent, in 8 inches. 20 131. The same sized specimens taken from plates exceed- ing 24 inches in width, shall have an ultimate strength of 46,000 pounds, and elongate 10 per cent. Bending Tests. j-^. All iron for tension members must bend cold for about 90 degrees, to a curve whose diameter is not over twice the thickness of the piece, without cracking. At least one sample in three must bend 180 degrees to this curve without cracking. When nicked on one side, and bent by a blow from a sledge, the fracture must be nearly all fibrous, showing but few crystalline specks. 133. Specimens from angle, plate less than 24 inches in width (130) and shaped iron, must stand bending cold through 90 degrees, and to a curve whose diameter is not over three times its thickness, without cracking. Specimens from plates wider than 24 inches must stand bending cold through 90 degrees ; and to a curve whose diameter is not over six times its thickness, without cracking. When nicked and bent the fracture must be mostly fibrous. 134. If any of the above material under the tests shows a decrease of stretch, accompanied by an increase of tensile strength, amounting to 500 pounds per square inch for each one per cent, change of stretch, this decrease of stretch will not be cause for rejection, if the material still satisfies the bending tests. 135. If the tests of the tension bars (127 and 128) show a decrease of the required tensile strength, accompanied with an increase of stretch, the decrease in the required tensile strength will not be cause for rejection if the tensile strength does not fall below the stated minimum require- ments, and the increase of stretch amounts to an additional per cent, for each 500 pounds decrease in the tensile strength. Rivet iron. j^. Rivets shall be made from the best refined iron, and must be capable of being bent cold until the sides are in close contact without sign of fracture on the convex side. Of- THE 21 UNIVERSITY OF STEEL. 137. The steel must be uniform in character for each specified kind. The finished bars, plates and shapes must be free from cracks on the faces or corners, and have a clean, smooth finish. No work shall be put upon any steel at or near the blue temperature or between that of boiling water and of ignition of hard wood sawdust. 138. All tests shall be made by samples cut from the fin- ished material after rolling. The samples to be at least 12 inches long, and to have a uniform sectional area not less than square inch. All broken samples must show uniform fine grained fractures of a blue steel-gray color, entirely free from fiery lustre or a blackish cast. 139. Medium Steel shall have an ultimate strength, when Medium steei. tested in samples of the dimensions above stated, of 62,000 to 68,000 pounds per square inch, an elastic limit of not- less than 33,000 pounds per square inch, and a minimum elonga- tion of 20 per cent, in 8 inches. 140. Before or after heating to a low cherry red and cool- ing in water at 82 degrees Fah., this steel must stand bend- ing to a curve whose inner radius is one and a half times the thickness of the sample, without cracking. 141. Soft Steel shall have an ultimate strength, on same soft steei. sized samples, of 54,000 to 62,000 pounds per square inch, an elastic limit not less than 30,000 pounds per square inch, and a minimum elongation of 25 per cent, in 8 inches. 142. Before or after heating to a light yellow heat and quenching in cold water, this steel must stand bending 180 degrees, to a curve whose inner radius is equal to the thick- ness of the sample, without sign of fracture. 143. All rivets will be made of soft steel, and the steel for rivets must, under the above bending test, stand closing solidly together without sign of fracture. CAST IRON. 144. Except where chilled iron is required, all castings cast iron. must be of tough, gray iron, free from cold shuts or injur- ious blow holes, true to form and thickness, and of a work- manlike finish. Sample pieces, i inch square, cast from the same heat of metal in sand moulds, shall be capable of sus- taining, on a clear span of 4 feet 6 inches, a central load of 500 pounds, when tested in the rough bar. A blow from a hammer shall produce an indentation on a rectangular edge of the casting without flaking the metal. TIMBER. Timber. 145. The timber shall be strictly first-class white pine, southern yellow pine or white oak bridge timber ; sawed true, and out of wind, full size, free from wind shakes, large or loose knots, decayed or sap wood, worm holes, or other defects impairing its strength or durability. It will be sub- ject to the inspection and acceptance of the Engineer. INSPECTION. inspection. 146. All facilities for inspection of the materials and workmanship shall be furnished by the contractor. He shall furnish without charge such specimens (prepared) of the several kinds of iron or steel to be used, as may be re- quired to determine their character. 147. The contractor must furnish the use of a testing machine capable of testing the above specimens at all mills where the iron or steel may be manufactured, free of cost. 148. Full sized parts of the structure may be tested at the option of the Engineer of the Railroad Company, but if tested to destruction, such material shall be paid for at cost, less its scrap value to the contractor, if it proves sat- isfactory. If it does not stand the specified tests, it will be considered rejected material, and be solely at the cost of the contractor. PAINTING. 149. All iron work before leaving the shop shall be thor- oughly cleaned from all loose scale and rust, and be given one good coating of pure raw linseed oil, well worked into all joints and open spaces. 23 150. In riveted work the surfaces coming in contact shall each be painted before being riveted together. Bottoms of bed-plates, bearing-plates, and any parts which are not ac- cessible for painting after erection, shall have two coats of paint ; the paint shall be a good quality of iron ore paint, subject to approval of the Engineer. 151. After the structure is erected, the iron work shall be thoroughly and evenly painted with two additional coats of paint, mixed with pure linseed oil, of such color as may be directed. All recesses which will retain water, or through which water can enter, must be filled with thick paint or some water-proof cement before receiving the final painting. 152. Pins, bored pin-holes and turned friction rollers shall be coated with white lead and tallow before being shipped from the shop. ERECTION. 153. The contractor shall furnish all staging and false Erection, work, shall erect and adjust all the iron work, and put in place all floor timbers, guards, etc., complete, ready for the rails. 154. The contractor shall so conduct all his operations as not to impede the operations of the road, interfere with the work of other contractors, or close any thoroughfare by land or water. 155. The contractor shall assume all risks of accidents to men or material prior to the acceptance of the finished struc- ture by the Railroad Company. The contractor must also remove all false work, piling and other obstructions, or unsightly material produced by his operations. FINAL TEST. 156. Before the final acceptance the Engineer may make Final Test. a thorough test by passing over each structure the specified loads, or their equivalent, at a speed not exceeding 45 miles an hour, and bringing them to a stop at any point by means of the air or other brakes, or by resting the maximum load upon the structure for twelve hours. 24: After such tests the structures must return to their origi- nal positions without showing any permanent change in any of their parts. SUPPLEMENTARY. The following special clauses shall apply in addition to previous general clauses, to the special work included in the attached contract: 25 Proposals for building and erecting complete, ready for the , a bridge over near on the Division, Railroad, in accordance with the attached specifications and accompanying profile, will be received up to The live load to be adopted for this bridge will be Class paragraph 23. "The most perfect system of rules to insure success must be interpreted upon the broad grounds of professional intelli- gence and common sense." GENERAL SPECIFICATIONS STEEL HIGHWAY AND ELECTRIC RAILWAY BRIDGES AND VIADUCTS. NEW AND REVISED EDITION, 19O1 By THEODORE COOPER, Consulting En.. SAt By THEODORE COOPER, M. Am, Soc. 0. E. Specifications for Steel Railroad Bridges, 1901, . . SO 50 u n " " previous editions 25 " Highway Bridges, 1901, . t>0 tt it T 81 a g Q I s M. 1 nch J> t- 00 00 00 00 00 05 OS Oi OS Oi 05 05 OS Oi OS JIO'BJ^ 9iqnop IT ^ JQJ SB auiBg JlD^a^ aiqnop l1 ^ aoj SB euiBg I 1 | 7 1 -f s $ J- || I S ? 2 s - I C) O 5M + s I ' I II II II II II II 37 p g H &8 3 3 M ., M S W It lo- gs so I OQ OSQ . * v >J 1*41 " t II II II fi? ftT ^ a? ^- Li w ^2 -fe^s ^-^T! i! ) - ^THTHOC3Ol^T-HCO < ^T-(C^JOO'-''M'^T (OO^rH >J>COGCOWOrt't-OCCiOQOOeOi-O?(TfO # ?* ? JOO^OOOOOOOOOOOOOOOOO )i-i(Mr-icft"^:eoci-* i aieooc<-xec^)aooc05t-^;coMO sssSssot2p:g2gi?:?:gSop 8|oo|S8888SSSSSS? -S ^ i a s o" d SSQQP QSOO< OooooSoooO< - -) XI T-H ( TJ- 10 J> 00 OS OS O ^J (g s s c ' SS B 38 1 O 02 o < I> 00 OS O O T-J 04 CO 03 ^ 10 O CO ^ 00 OC g g rH 1C ^ (M 1-1 ^M S fc, t, o o S " The most perfect system of rules to insure success must be interpreted upon the broad grounds of professional intelli- gence and common sense." GENERAL SPECIFICATIONS FOR STEEL RAILROAD BRIDGES AND VIADUCTS. NEW AND REVISED EDITION, 1 9 O-l By THEODORE COOPER, Consulting Engineer. By THEODORE COOPER, M, Am, Soc, 0, E. Specifications for Steel Railroad Bridges, 1901, . . $0 50 " previous editions 25 " " Highway Bridges, 1901, . . 50 " previous editions 25 American Railroad Bridges (reprint from Transac- tions of American Society of Civil Engineers, July, 1889), 60 pages, 8vo, cloth, . . 2 00 FOR SALE BY ENGINEERING NEWS PUBLISHING COMPANY, 22O Broad way, New York. Copyright by THEODORE COOPER, Consulting Engineer, 35 Broadway, New York. General Specifications for Steel Railroad Bridges and Viaducts, ; SIXTH EDITION. 1901_ GENERAL DESCRIPTION. 1. All the structures shall be of wrought steel, as specified. { 128-141.) Cast-iron or cast- steel may be used in the machinery of movable bridges and in special cases for bed- plates. 2. The following kinds of girders shall preferably be Kind of Girders. employed: Spans, up to 20 feet Rolled beams, or longitudinal trough floors. " - 20 to 75 " Riveted plate girders. 75 to 120 " Riveted plate or lattice girders. " 1 20 to 150 " Lattice or pin-connected trusses. " over 150 " Pin-connected trusses. Generally " double track through " bridges will have but two trusses, to avoid spreading the tracks at bridges. In calculating strains the length of span shall be under- Length of Span, stood to be the distance between centres of end pins for trusses, and between centres of bearing plates for all beams and girders. 3. The girders shall be spaced, with reference to the of the bridge, as required by local circumstances, and directed by the Engineer of the Railroad Company. ( 5.) Longitudinal floor girders shall in no case be less than three feet and three inches from centre line of tracks for single track bridges, or one-half standard distance centre to centre of tracks for double track bridges. (6.) Head-room. ^ p or a ii through bridges and overhead structures there shall be a clear head-room of 21 feet above the base of the rails, for a width of six feet over each track. ciear width. cj. In all through bridges the clear width from the centre of the track to any part of the trusses shall not be less than seven (7) feet at a height exceeding one foot above the rails where the tracks are straight, and an equivalent clearance, where the tracks are curved. [The additional clearance required on curves for passen- ger cars, 54 feet c. to c. of trucks and 75 feet over all, will be as follows : For curvature, 0.8 D inches on each side ; 1.6 D inches between tracks, where D equals degree of curve. For elevation, the clearance at top of the car on inside of curve must be increased 2^ inches for each inch of track elevation ] 6. The standard distance, centre to centre of tracks on straight lines, will be feet for R. R. Trestle Towers. 7. Each trestle bent shall, as a general rule, b? composed of two supporting columns, and the bents united in pairs to form towers ; each tower thus formed of four columns shall be thoroughly braced in both directions, and have struts between the feet of the columns. Transversely the columns shall have a batter of not less than one horizontal to six vertical for single track, and one horizontal to eight vertical for double track. The feet of the columns must be secured to an anchorage capable of resisting double the specified wind forces. ( 25, 27.) 8. Each tower shall have sufficient base, longitudinally, to be stable when standing alone, without other support than its anchorage. ( 25, 27.) Trestle spans. 9. Tower spans for high trestles shall not be less than 30 feet. 10. Unless otherwise specified, the form of bridge trusses Form ot may be selected by the bidder ; for through bridges, the end vertical suspenders and two panels of the lower chord, at each end, will be made rigid members. In general, all spans shall have end floor beams for supporting the stringers; such end floor beams may have one intermediate bearing on the masonry. In through bridges, the floor beams shall be riveted to the posts, above or below the pins. 11. All lateral, sway and portal bracing must be made of Lateral Bracing, shapes capable of resisting compression as well as tension, and must have riveted connections. 12. The wooden floors will consist of transverse ties or wooden Floor, floor timbers; their scantling will vary in accordance with the design of the supporting steel floor. ( 15.) They shall be spaced with openings not exceeding six inches, and shall be notched down y 2 inch and be secured 'to the supporting girders by f-inch bolts at distances not over six feet apart. For deck bridges the ties will extend the full width of the bridge, and for through bridges at least every other tie shall extend the full width of bridge fora footwalk. 13. There shall be a guard timber (scantling not less than Guard Timbers. 6x8") on each side of each track, with its inner face parallel to and at feet inches from centre of track. Guard timbers must be notched one inch over every floor timber, and be spliced over a floor timber with a half-and-half joint of six inches lap. Each guard timber shall be fastened to every third floor timber and at each splice with a three- quarter (|) inch bolt. All heads or nuts on upper faces of ties or guards must be countersunk below the surface of the wood. ( 61.) 14. The guard and floor timbers must be continuous over all piers and abutments. 15. The maximum strain allowed upon the extreme fibre Allowed strain of the best yellow pine or white oak floor timbers will be n 1,000 pounds per square inch. The weight of a single en- gine wheel may be assumed as distributed over three ties, spaced as per 12. 1 6. The floor timbers from centre to each end of span must be notched down over the longitudinal girders so as to reduce the camber in the track, as directed by the Engineer. 17. All the floor timbers shall have a full and even bear- ing upon the stringers; no open joints or shims will be allowed. 1 8. On curves the outer rail must be elevated, as may be directed by the Engineer. Proposals. iQ. In comparing different proposals, the relative cost to the Railroad Company of the required masonry or changes in existing work will be taken into consideration. 20. Contractors in submitting proposals shall furnish com- plete strain sheets, general plans of the proposed structures, and such detail drawings as will clearly show the dimen- sions of all the parts, modes of construction and the sec- tional areas. 21. Upon the acceptance of the proposal and the execu- tion of contract, all working drawings required by the En- gineer must be furnished free of cost. Approval of 22 - No work shall be commenced or materials ordered until the working drawings are approved by the Engineer in writing; if such working drawings are detained more than one week for examination, the Contractor will be allowed an equivalent extension of time. LOADS. 23. All the structures shall be proportioned to carry the following loads: ist. The weight of metal in the structure and floor. Dead Load. 2d. The weight of rails, fastenings, ties, guards, footwalk and ballast when used. The rails and fastenings being assumed at 100 pounds per foot of track ; timber at 4^ pounds per foot B. M. ; and ballast at no pounds per cubic foot. Minimum will be assumed at 400 pounds per foot of track. These two items, taken together, shall constitute the " dead load." h A ""* a Jl.T? t* - 1 p $* "aw 1 1! 11 It A ""^ it A ~G 17550 19500 22750 26000 32500 - 17550 19500 22750 26000 32500 C - 17550 19500 22750 26000 32500 Hi V- - 17550 19500 22750 26000 32500 1 to (!) ' 27000 30000 35000 40000 50000 H " >< 27000 30000 35000 40000 50000 fl . "S3 = 9,000 40 for live load strains. and trestles. 1 8,000 80 for dead load strains. 9 End posts are not to be considered chord segments. Lateral struts j and rigid P= 13,000 60 for wind strains; bracing. for live load strains use two-thirds of the above. ( 27, 29, P=the allowed strain in compression per square inch of cross-section, in pounds. /=the length of compression member, in inches, c. to c., of connections. r=the least radius of gyration of the section, in inches. No compression member, however, shall have a length exceeding 100 times its least radius of gyration for main members, or 120 times for laterals. Soft Steel may be used in compression with unit strains Soft steel, fifteen per cent, less than those allowed for Medium SteeL For swing bridges and other movable structures, the dead load unit strains during motion must not exceed f- of the above allowed unit strains for dead load on stationary structures. 35. For long span bridges, when the ratio of the length and width of span is such that it makes the top chords act- ing as a whole, a longer column than the segments of the chord, the chord will be proportioned for this greater length. 36. All members and their connections subject to alter- Alternate nate strains of tension and compression shall be propor- Strams ' tioned to resist each kind of strain. Both of the strains shall, however, be considered as increased by an amount equal to T 8 F of the least of the two strains, for determining the sectional areas by the above-allowed unit strains. (3i,34.) 37. The strains in the truss members or trestle posts Effect of wind from the assumed wind forces need not be considered ex-s? r n. rd cept as follows : ist. When the wind strains on any member exceed 30 10 per cent, of the maximum strains due to the dead and live loads upon the same member. The section shall then be increased until the total strain per square inch will not exceed by more than 30 per cent, the maximum fixed for dead and live loads only. 2d; When the wind strain alone or in combination with a possible temperature strain, can neutralize or reverse the strains in any member. 38. The rivets in all members, other than those of the floor and lateral systems, must be so spaced that the shear- ing strain per square inch shall not exceed 9,000 pounds ; nor the pressure on the bearing surface (diameter X thick- ness of the piece) of the rivet-hole exceed 15,000 pounds per square inch. The rivets in all members of the floor system, including all hanger connections, must be so spaced that the shearing strains and bearing pressures shall not exceed 80 per cent, of the above limits. The rivets in the lateral and sway bracing will be allowed 50 per cent, increase upon the above limits for lateral forces as per 24, 25, but not per 27, 29. In the case of field riveting (and for bolts as per 61) the above-allowed shearing strains and pressures shall be re- duced one-third. Rivets and bolts must not be used in direct tension. 39. Pins shall be proportioned so that the shearing strain shall not exceed 9,000 pounds per square inch ; nor the pressure on the bearing surface of any member (other than forged eye-bars, see 85) connected to the pin be greater per square inch than 15,000 pounds ; nor the bending strain exceed 18,000 pounds, when the applied forces are consid- ered as uniformly distributed over the middle half of the bearing of each member. Combined 4O. When any member is subjected to the action of both ins> axial and bending strains, as in the case of end posts of through bridges ( 37), or of chords carrying distributed floor loads, it must be proportioned so that the greatest fibre strain will not exceed the allowed limits of tension or compression on that member. 11 If the fibre strain resulting from the weight only, of any member, exceeds ten per cent, of the allowed unit strain on such member, such excess must be considered in propor- tioning the areas. 41. In beams and plate girders the compression flanges compression shall be made of same gross section as the tension flanges. 42. Riveted longitudinal girders shall have, preferably, a Depth of depth not less than ^ of the span. Rolled beams used as longitudinal girders shall have, preferably, a depth not less than T ^ of the span. 43. Plate girders shall be proportioned upon the supposi-pi ate Girders, tion that the bending or chord strains are resisted entirely et by the upper and lower flanges, and that the shearing or web strains are resisted entirely by the web-plate; no part of the web-plate shall be estimated as flange area. The distance between centres of gravity of the flange areas will be considered as the effective depth of all girders. 44. The webs of plate girders must be stiffened at inter- web Plates, vals, not exceeding the depth of the girders or a maximum of 5 feet, wherever the shearing strain per square inch ex- ceeds the strain allowed by the following formula : Allowed shearing strain = 10,000 75/7, where H = ratio of depth of web to its thickness ; but no web-plates shall be less than three-eighths of an inch in thickness. 45. All stiffeners must be capable of carrying the maxi- stiffeners. mum vertical shear without exceeding the allowed unit strain. P= 10,000 45-. r Each stiffener must connect to the webs by enough rivets to transfer the maximum shear to or from the webs. 46. Rolled beams shall be proportioned ( 31, 41) by Roiled Beams, their moments of inertia. 47. The areas of counters shall be determined by taking counters, the difference in areas due to the live and dead load strains considered separately ( 31); the counters in any one panel must have a combined sectional area of at least three square 12 inches, or else must be capable of carrying all the counter live load in that panel. ( 86.) 48. Counters shall be provided and proportioned, so that a future increase of 25 per cent, in the specified live load shall not in any case increase the allowed unit strain more than 25 per cent. DETAILS OF CONSTRUCTION. Details. 49. All the connections and details of the several parts of the structures shall be of such strength that, upon testing, rupture will occur in the body of the members rather than in any of their details or connections. 50. Preference will be had for such details as shall be most accessible for inspection, cleaning and painting ; no closed sections will be allowed. Riveting. 51. The pitch of rivets in all classes of work shall never exceed 6 inches, or sixteen times the thinnest outside plate, nor be less than three diameters of the rivet. 52. The rivets used shall generally be and f inch diam- eter. 53. The distance between the edge of any piece and the centre of a rivet-hole must never be less than ij inches, except for bars less than 2\ inches wide ; when practicable it shall be at least two diameters of the rivet. 54. For punching, the diameter of the die shall in no case exceed the diameter of the punch by more than T A of an inch, and all holes must be clean cuts without torn or ragged edges. 55. All rivet holes must be so accurately spaced and punched that when the several parts forming one member are assembled together, a rivet -^ inch less in diameter than the hole can generally be entered, hot, into any hole, with- out reaming or straining the metal by " drifts "; occasional variations must be corrected by reaming. 56. The rivets when driven must completely fill the holes. The rivebheads must be round and of a uniform size for the same sized rivets throughout the work. They must be full and neatly made, and be concentric to the 13 rivet-hole, and thoroughly pinch the connected pieces to- gether. 57. Wherever possible, all rivets must be machine driven. The machines must be capable of retaining the applied pressure after the upsetting is completed. No hand-driven rivets exceeding J inch diameter will be allowed. 58. Field riveting must be reduced to a minimum or entirely avoided, where possible. 59. All holes for field rivets, except those in connections of the lateral and sway systems, shall be accurately drilled or reamed to an iron template or be reamed true while the parts are temporarily connected together. 60. The effective diameter of a driven rivet will be as- Net sections, sumed the same as its diameter before driving. In deduct- ing the rivet-holes to obtain net sections in tension mem- bers, the diameter of the rivet-holes will be assumed as -J inch larger than the undriven rivets. The rupture of a riveted tension member is to be con- sidered as equally probable, either through a transverse line of rivet-holes or through a diagonal line of rivet-holes, where the net section does not exceed by 30 per cent, the net section along the transverse line. The number of rivet-holes to be deducted for net section will be determined by this condition. 61. When members are connected by bolts the holes must Bolts< be reamed parallel and the bolts turned to a driving fit. All bolts must be of neat lengths, and shall have a washer under the heads and nuts where in contact with wood. Bolts must not be used in place of rivets, except by special permission. 62. All nuts must be of hexagonal shape. 63. All joints in riveted tension members must be fully splices. and symmetrically spliced. 64. Riveted tension members shall have an effective sec- tion through the pin-holes 25 per cent, in excess of the net section of the member, and back of the pin at least 75 per cent, of the net section through the pin-hole. 65. In continuous compression members, as chords and 14 trestle posts, the abutting joints with planed faces must be placed as close to the panel points as is practicable, and the joints must be spliced on all sides with at least two rows of closely pitched rivets on each side of the joint. Joints in long posts must be fully spliced. Abutting joints. 66. In compression members, abutting joints with un- tooled faces must be fully spliced, as no reliance will be placed on such abutting joints. The abutting ends must, however, be dressed straight and true, so there will be no open joints. . 5^ Xhe webs of plate girders must be spliced at all joints by a plate on each side of the web. . 68. All web-plates must have stiffeners over bearing points and at points of local concentrated loadings ; such stiffeners must be fitted at their ends to the flange angles, at the bearing points. 69. All other angles, filling and splice plates on the webs of girders and riveted members must fit at their ends to the flange angles, sufficiently close to be sealed, when painted, against admission of water. Web piates. 70. Web-plates of all girders must be arranged so as not to project beyond the faces of the flange angles, nor on the top be more than -^ inch below the face of these angles, at any point. 71. Wherever there is a tendency for water to collect, the spaces must be filled with a suitable waterproof material. Flange Plates. 72. In girders with flange plates, at least one-half of the flange section shall be angles or else the largest sized angles must be used. Flange plates must extend beyond their theoretical length, two rows of rivets at each end. 73. In lattice girders and trusses the web members must be double and connect symmetrically to the webs of the chords. The use of plates or flats, alone, for tension mem- bers mnst be avoided, where it is possible; in lattice trusses, the counters, suspenders and two panels of the lower chord, at each end, must be latticed ; all other ten- sion members must be connected by batten plates or latticed. (See Arts. 90, 91 and 92.) it 74. The compression flanges of beams and girders shall be compression stayed against ^transverse crippling when their length is more than sixteen times their width.' *> - 75. The unsupported width (distance between rivets) of width of Plates, plates subject to compression shall not exceed thirty times their thickness ; except cover plates of top chords and end posts, which will preferably be limited to forty times their thickness ; where a greater relative width is used in chords and end posts, however, only forty times the thickness shall be considered as effective section. 76. The flange plates of all girders must be limited in width so as not to extend beyond the outer lines of rivets connecting them with the angles, more than five inches or more than eight times the thickness of the first plate. Where two or more plates are used on the flanges, they shall either be of equal thickness or shall decrease in thickness outward from the angles. 77. Where the floor timbers are supported at their ends on the flange of one angle, such angle must have two rows of rivets in its vertical leg, spaced not over 4 inches apart. 78. For main members and their connections no material Thickness of shall be used of a less thickness than f of an inch ; and for laterals and their connections, no material less than T 5 F of an inch in thickness ; except for lining or filling vacant spaces. 79. The heads of eye-bars shall be so proportioned and Eye Bars, made, that the bars will preferably break in the body of the original bar rather than at any part of the head or neck. The form of the head and the mode of manufacture shall be subject to the approval of the Engineer of the Railroad Company. (Art. 141.) 80. The bars must be free from flaws and of full thick- ness in the necks. They shall be perfectly straight before boring. The holes shall be in the centre of the head, and on the centre line of the bar. 81. The bars must be bored to lengths not varying from the calculated lengths more than ^ of an inch for each 25 feet of total length. 16 82. Bars which are to be placed side by side in the structure shall be bored at the same temperature and of such equal length that upon being piled on each other the pins shall pass through the holes at both ends without driving. 83. The lower chord shall be packed as narrow as possi- ble. Pins - 84. The pins shall be turned straight and smooth ; chord pins shall fit the pin-holes within ^ of an inch, for pins less than 4^ inches diameter ; for pins of a larger diameter the clearance may be -f$ inch. 85. The diameter of the pin shall not be less than three- quarters the largest dimension of any eye-bar attached to it. The several members attaching to the pin shall be so packed as to produce the least bending moment upon the pin, and all vacant spaces must be filled with wrought fill- ing rings. Upset Ends. 86. All bars with screw ends shall be upset at the ends, so that the diameter at the bottom of the threads shall be Y 1 ^ inch larger than any part of the body of the bar. Where closed sleeve nuts are used on adjustable members the effective length of thread shall be legibly stamped at the screw ends of each bar. Adjustable counters to be avoided where practicable. 87. All threads must be of the United States standard, except at the ends of the pins. Hangers. 88. Floor beam hangers when permitted shall be made without adjustment and so placed that they can be readily examined at all times. ( 10.) 89. All the floor beams must be effectually stayed against end motion or any tendency to rotate from the action of the lateral system. Compression QO. Compression members shall be of steel, and of ap- Members. 91. The pitch of rivets at the ends of compression mem- bers shall not exceed four diameters of the rivets for a length equal to twice the width of the member. 92. The open sides of all compression members shall be 17 stayed by batten plates at the ends and diagonal lattice- work at intermediate points. The batten plates must be placed as near the ends as practicable, and shall have a length not less than the greatest width of the member or i times its least width. The size and spacing of the lattice bars shall be duly proportioned to the size of the member. They must not be less in width than 2 inches for members 9 inches or less in width, nor 2\ inches for members 12 to 9 inches in width, nor 2^ inches for members 15 to 12 inches in width. Single lattice bars shall have a thickness not less than ^ or double lattice bars connected by a rivet at the intersection, not less than -fa of the distance between the rivets connecting them to the members. They shall be in- clined at an angle not less than 60 to the axis of the mem- ber for single latticing, nor less than 45 for double lattic- ing with riveted intersections. The pitch of the latticing must not exceed the width of the channel plus nine inches. 93. Where necessary, pin-holes shall be reinforced by plates, some of which must be of the full width of the member, so the allowed pressure on the pins shall not be exceeded, and so the strains shall be properly distributed over the full cross-section of the members. These reinforc- ing plates must contain enough rivets to transfer their pro- portion of the bearing pressure, and at least one plate on each side shall extend not less than six inches beyond the edge of the batten plates. ( 92.) 94. Where the ends of compression members are forked to connect to the pins, the aggregate compressive strength of these forked ends must equal the compressive strength of the body of the members. 95. In compression chord sections and end posts, the material must mostly be concentrated at the sides, in the angles and vertical webs. Not more than one plate, and this not exceeding \ inch in thickness, shall be used as a cover plate, except when necessary to resist bending strains, or to comply with 75. (40.) 96. The ends of all square-ended members shall be planed smooth, and exactly square to the centre line of strain. 18 Floor Beams o7. The ends of all floor beams and stringers shall be and Stringers. " faced true and square, and to correct lengths. Allowance must be made in the thickness of the end angles to provide for such facing without reducing the required effective strength of such end angles. 98. All members must be free from twists or bends. Por- tions exposed to view shall be neatly finished. Pin-Hoies. 99. Pin-holes shall be bored exactly perpendicular to a vertical plane passing through the centre line of each mem- ber, when placed in a position similar to that it is to occupy in the finished structure. ico. The several pieces forming one built member must fit closely together, and when riveted shall be free from twists, bends or open joints. Transverse loi. All through bridges shall have latticed portals, of Brtfin? approved design, at each end of the span, connected rigidly to the end posts and top chords. They shall be as deep as the specified head-room will allow, and provision shall be made in the end posts for the bending strains from wind pressure. (24.) (4.) ( 11.) 102. When the height of the trusses exceeds 25 feet, an approved system of overhead diagonal bracings shall be attached to each post and to the top lateral struts. 103. All members of the web, lateral, longitudinal or sway systems must be securely riveted at their intersections to prevent sagging and rattling. 104. Pony trusses and through plate or lattice girders shall be stayed by knee braces or gusset plates attached to the top chords at the ends and at intermediate points, and attached below to the cross floor beams or to the transverse struts. Deck Bridges. io5. All deck girders shall have transverse braces at the ends. All deck bridges shall have transverse bracing at each panel point. This bracing shall be proportioned to resist the unequal loading of the trusses. 106. In double-track deck bridges, where three trusses are used, all three trusses will be made of equal strength ; the unequal loading being distributed through the trans- 19 verse diagonal bracing as a live load. (For the purpose of reducing the unequal deflection under single-track load- ings.) 107. All bed-plates must be of such dimensions that the Bed Plates, greatest pressure upon the pedestal stone shall not exceed 250 pounds per square inch. 108. All bridges over 80 feet span shall have hinged Friction bolsters on both ends, and at one end nests of turned fric- tion rollers running between planed surfaces. These rollers shall not be less than 2-J inches diameter for spans 100 feet or less, and for greater spans this diameter shall be increased in proportion of i inch for 100 feet additional. The rollers shall be so proportioned that the pressure per lineal inch of roller shall not exceed the product of the diameter in inches by 300 pounds (3Ood.). The rollers must be of machinery steel and the bearing plates of medium steel. The rollers and bearings must be so arranged that they can be readily cleaned and so that they will not hold water. 109. Bridges less than 80 feet span shall be secured at one end to the masonry, and the other end shall be free to move longitudinally upon smooth surfaces. 1 10. Where two spans rest upon the same masonry, a con- tinuous plate, not less than f inch thick, shall extend under the two adjacent bearings, or the two bearings must be rigidly tied together. in. Pedestals shall be made of riveted plates and angles. Pedestals and All bearing surfaces of the base plates and vertical webs must be planed. The vertical webs must be secured to the base by angles having two rows of rivets in the vertical legs. No base plate or web connecting angle shall be less in thickness than inch. The vertical webs shall be of sufficient height and must contain material and rivets enough to practically distribute the loads over the bearings or rollers. Where the size of the pedestal permits, the vertical webs must be rigidly connected transversely. 112. All the bed-plates and bearings under fixed and 20 movable ends must be fox-bolted to the masonry ; for trusses, these bolts must not be less than i inches diameter ; for plate and other girders, not less than J inch diameter. The contractor must furnish all bolts, drill all holes and set bolts to place with sulphur or Portland cement. 113. While the expansion ends of all trusses must be free to move longitudinally under changes of temperature, they shall be anchored against lifting or moving sideways, camter. 114. All bridges shall be cambered by giving the panels of the top chord an excess of length in the proportion of % of an inch to every ten feet. Trestle Towers. 115. The lower struts in trestle towers must be capable of resisting the strains due to changes of temperature or of moving the tower pedestals under the effects of expansion or contraction. For high or massive towers, these lower struts will be securely anchored to intermediate masonry piers, or the tower pedestals will have suitably placed friction rollers, as may be directed by the Engineer. 116. All joints in the tower columns shall be fully spliced for all possible tension strains, and to hold the parts firmly in position. ( 65.) 117. Tower footings and bed-plates must be planed on all bearing surfaces ; and the holes for anchor bolts slotted to allow for the proper amount of movement. ( 28.) workmanship. iiS. All workmanship shall be first-class in every par- ticular. 119. All eye-bars must be made of medium steel. Eye-Bars. i2o. Eye-bars, all forgings and any pieces which have been partially heated or bent cold must be wholly an- nealed. Crimped stiffeners need not be annealed. 121. No reliance will be placed upon the welding of steel. 122. No sharp or unfilleted angles or corners will be allowed in any piece of metal. Medium steel. 123. Medium steel may be used in compression in chords, posts and pedestals without reaming of punched holes, for all thicknesses of metal, which will stand the drifting test 21 ( !35); provided all sheared edges are planed off to a depth of J> inch. In all other cases medium steel over inch thick must have all sheared edges planed off to a depth of inch and all holes drilled or reamed to a diameter inch larger than the punched holes, so as to remove all the sheared surface of the metal. 124. Soft steel need not be reamed if it satisfies the drift- ing test ( 135, 136). 125. All parts of any tension or compression flange or member, must be of the same kind of steel, but webs of plate girders and the tension members of all girders, plate or lattice, may be made of soft steel in connection with compression members of medium steel. 126. All splices must be of the same kind of steel as the parts to be joined. 127. Pilot nuts must be used during the erection to pro- pnot Nuts tect the threads of the pins. QUALITY OF MATERIAL. STEEL. 128. All steel must be made by the Open Hearth process. The phosphorus must not exceed 0.06 of one per cent, for steel made by the acid method, or 0.04 for steel by the basic method. 129. The steel must be uniform in character for each specified kind. The finished bars, plates and shapes must be free from cracks on the faces or corners, and have a clean, smooth finish. No work shall be put upon any steel at or near the blue temperature or between that of boiling water and of ignition of hard wood sawdust. 130. The tensile strength, elastic limit* and ductility shall be determined by samples cut from the finished material after rolling. The samples to be at least 12 inches long, * For the purpose of these specifications, the Elastic Limit will be considered the least strain producing a visible permanent elongation in a length of 8 inches, as shown by scribe marks of a pair of finely pointed dividers. lithe yield point or drop of the beam can be calibrated for any machine and its speed to represent the elastic limit within 5 per cent., it may be used for general cases. Test reports must state by which method the elastic limit was determined. and to have a uniform^ sectional area not less than;J sqtfafe inch. 131. Material which is to be used without annealing or further treatment is to be tested in the condition in which it comes from the rolls. When material is to be annealed or otherwise treated before use, the specimen representing such material is to be similarly treated before testing, for tensile strength. The elongation shall be measured on an original length of 8 inches. Two test pieces shall be taken from each melt or blow of finished material, one for tension and one for bend- ing. (Art. 147.) 132. All samples or full-sized pieces must show uniform fine grained fractures of a blue steel-gray color, entirely free from fiery lustre or a blackish cast. Medium steel. 133. Medium Steel shall have an ultimate strength, when tested in samples of the dimensions above stated, of 60,000 to 68,000 pounds per square inch, an elastic limit of not less than one-half of the ultimate strength, and a minimum elongation of 22 per cent, in 8 inches. Steel for pins may have a minimum elongation of 15 per cent. 134. Before or after heating to a low cherry red and cooling in water at 82 degrees Fah., this steel must stand bending to a curve whose inner radius is one and a half times the thickness of the sample, without cracking. 135. For all medium steel, f inch or less in thickness, rivet holes punched as in ordinary practice ( 52, 53, 54), must stand drifting to a diameter one-third greater than the original holes, without cracking either in the periphery of the holes or on the external edges of the piece, whether they be sheared or rolled. soft steei. 136. Soft Steel shall have an ultimate strength, on same sized samples, of 54,000 to 62,000 pounds per square inch, an elastic limit not less than one-half the ultimate strength, and a minimum elongation of 25 per cent, in 8 inches. For soft steel the above drifting test ( 135) shall apply to all material to be riveted. 137. Before or after heating to a light yellow heat and 23 quenching in cold water, this steel must stand bending 180 degrees, to a curve whose inner radius is equal to the thickness of the sample, without sign of fracture. 138. Rivet Steel shall have an ultimate strength of 5o,ooo RivetSteel to 58,000 pounds per square inch, an elastic limit not less than one-half the ultimate strength and an elongation of 26 per cent. 139. The steel for rivets must, under the above bending test (137), stand closing solidly together without sign of fracture. 140. Eye-bar material, i^ inches and less in thickness, E ye Bars, shall, on test pieces cut from finished material, fill the above requirements. For thicknesses greater than i inches, there will be allowed a reduction in the percentage of elongation of I per cent, for each -J of an inch increase of thickness, to a minimum of 20 per cent. (Art. 119.) 141. Full sized eye-bars shall show not less than 10 per cent, elongation in the body of the bar, and an ultimate strength not less than 56,000 pounds per square inch. Should a bar break in the head, but develop 10 per cent, elongation and the ultimate strength specified, it shall not be cause for rejection, provided not more than one-third of the total number of bars tested break in the head. 142. Pins over 7 inches in diameter shall be forged. Blooms for pins shall have at least three times the sectional area of the finished pins. 143. A variation of cross-section or weight in the finished members of 2% per cent, from the specified size may be cause for rejection. STEEL CASTINGS. 144. Steel castings will be used for drawbridge wheels, steei castings, track segments and gearing. (Art. i.) They must be true to form and dimensions, of a work- manlike finish and free from injurious blowholes and defects. All castings must be annealed. When tested in specimens of uniform sectional area of at least ^ square inch for a distance of 2 inches, they must f /^V I OF THF \ f UNIVERSITY ) \ ^ 24 show an ultimate strength of not less than 67,000 pounds per square inch, an elastic limit of one-half the ultimate, and an elongation in 2. inches of not less than 10 per cent. The metal must be uniform in character, free from hard or soft spots, and be capable of being properly tool finished. CAST IRON. cast iron. HS- Except where cast steel or chilled iron is required, all castings must be of tough, gray iron, free from cold shuts or injurious blowholes, true to form and thickness, and of a workmanlike finish. Sample pieces, i inch square, cast from the same heat of metal in sand moulds, shall be capable of sustaining, on a clear span of 12 inches, a central load of 2,400 pounds, when tested in the rough bar. A blow from a hammer shall produce an indentation on a rectangu- lar edge of the casting without flaking the metal. TIMBER. Timber. 146. The timber, unless otherwise specified, shall be strictly first-class southern yellow pine or white oak bridge timber, sawed true, and out of wind, full size, free from wind shakes, large or loose knots, decayed or sap wood, worm holes, or other defects impairing its strength or dur- ability. It will be subject to the inspection and acceptance of the Engineer. INSPECTION. inspection. 147. All facilities for inspection of the materials and workmanship shall be furnished by the contractor. He shall furnish without charge such specimens (prepared) of the several kinds of steel to be used, as may be required to determine their character. 148. The contractor must furnish the use of a testing machine capable of testing the above specimens at all mills where the steel may be manufactured, free of cost. 149. Full sized parts of the structure may be tested at the option of the Engineer of the Railroad Company, but if tested to destruction, such material shall be paid for at 25 cost, less its scrap value to the contractor, if it proves satis- factory. If it does not stand the specified tests, it will be considered rejected material, and be solely at the cost of the contractor. PAINTING. 150. All metal work before leaving the shop shall be thor- Painting, oughly cleaned from all loose scale and rust, and be given one good coating of pure raw linseed oil, well worked into all joints and open spaces. 151. In riveted work the surfaces coming in contact shall each be painted before being riveted together. Bottoms of bed-plates, bearing-plates, and any parts which are not accessible for painting after erection, shall have two coats of paint ; the paint shall be a good quality of iron ore paint, mixed with pure linseed oil, unless otherwise directed. It will be subject to approval of the Engineer. 152. After the structure is erected, the metal work shall be thoroughly and evenly painted with two additional coats of paint, mixed with pure linseed oil. All recesses which will retain water, or through which water can enter, must be filled with thick paint or some waterproof cement before receiving the final painting. 153. Pins, bored pin-holes, screw threads and turned fric- tion rollers shall be coated with white lead and tallow before being shipped from the shop. ERECTION. 154. The contractor, unless it be otherwise specified, shall Erection, furnish all staging and false work, shall erect and adjust all the metal work, and put in place all floor timbers, guards, etc., complete, ready for the rails. 155. The contractor shall so conduct all his operations as not to impede the operations of the road, interfere with the work of other contractors, or close any thoroughfare by land or water. 156. The contractor shall assume all risks of accidents to men or material prior to the acceptance of the finished structure by the Railroad Company. The contractor must also remove all false work, piling* and other obstructions, or unsightly material produced by his operations. FINAL TEST. Final Test. i$f. Before the final acceptance the Engineer may make a thorough test by passing over each structure the specified loads, or their equivalent, at a speed not exceeding 60 miles an hour, and bringing them to a stop at any point by means of the air or other brakes, or by resting the maximum load upon the structure for twelve hours. Alter such tests the structures must return to their orig- inal positions without showing any permanent change in any of their parts. EXPORT WORK. Export work. All plans, including working drawings, must be submitted for the examination and approval of the Consulting Engineer before the material is ordered or any work done. Any proposed modification of accepted plans, to adapt them to the plant and methods of the manufacturer or to facilitate the prompt delivery of the work, must also be submitted to and approved by the Consulting Engineer, before such changes can be allowed. In all designs, the length and size of parts must be so arranged that they can be readily handled and stored dur- ing transportation to the site. Length of bars, posts, chords and pieces of small section must not exceed feet. Length of girders or girder sections over feet in width must not exceed feet. Weight of any single piece must not exceed pounds. Pins, roller-nests, bolts, rivets and all small pieces must be packed in strong, iron-bound boxes, with the detailed contents of each box legibily marked on the outside. Boxes to be consecutively lettered or numbered. 27 The screw-ends of all bars to be securely protected by canvass wrapped and wired about the same. Every piece must not only be legibiiy marked by paint, but also by letters stamped on the metal, showing its loca- tion in the structure. All necessary rivets for the field connections, with an extra allowance of 25 per cent, for each kind, shall be sent with each shipment. The customary pilot- nuts ( 127) for all pins shall be sent with the pins. Proposals for building and erecting complete, ready for the .: , a bridge over near on the Division, Railroad, in accordance with the attached specifications and accompanying profile, will be received up to The live load to be adopted for this bridge will be Class E , paragraph 23. APPENDIX. 30 TABLE I. MAXIMUM MOMENTS M, END SHEARS S, AND FLOOR-BEAM REACTIONS R, PER TRACK, FOR LOADING E 40, FOR GIRDER BRIDGES. Span L. Ft. Max. mom. M. Ft.-lbs. Max. end shear 8. Ft.-lbs. Max. floor reac. R. Ft.-lbs. EQUIVALENT UNIFORM LOAD. M. Lbs. S. Lbs. R. Lbs. 10.... 112 500 131 400 160 000 190000 220 000 250 000 280000 310 000 340 000 373 200 412 500 452 000 491 400 530 800 570 400 610000 649 600 689 200 731 000 775 800 821 000 865 700 910 800 955 600 1 000 700 . 1 046 000 1 097000 1 148 500 1 200 000 1 253 500 1 311 000 1 427000 1 543 000 1 659 000 1 776 000 1 902 000 2 030 000 2 162000 2 304 000 2 446 000 2 599 000 2 753 000 2 911 000 3 079 000 3247 000 3 415 000 3 584 000 3 758 000 3 942 000 4 129 000 4 321 000 4 513 000 4 713 000 4 919 000 5 128000 5 341 000 5 552 000 5 771 000 5 988 000 6 213 000 6 440 000 7 075 000 7774 000 8 490 000 9228 000 9 993 000 60 000 65 500 70 000 73 800 77 200 80 000 85 000 89 500 93 400 96 800 100 000 102 800 105 500 107 900 110 800 113 600 116 100 118 500 120 800 123 100 126 100 128 800 131 500 ias 900 136 100 138 400 141 100 143 800 146 200 148 600 150 800 156 200 161 100 165 600 169 600 . 174 200 178 500 182 400 186 000 190800 195 200 200 200 205 200 210 000 215 600 221 000 226 700 232 600 238 100 243 400 248 400 253 800 259 000 264 200 269 400 274 500 279 600 284 TOO 289 600 295 000 300 000 312 200 324 000 335 800 347 400 358 800 80 000 87 300 93 300 98 500 104 300 109 300 113700 117 600 121 300 125 800 131 100 136000 140 300 144 300 148 000 151 300 155400 160 100 164 600 168 700 172 500 176 900 182 000 186 700 191 100 195200 9 000 8 690 8 890 9 000 8 980 8 890 8 750 8 580 8 400 8270 8 250 8 200 8 120 8030 7 920 7 810 7 690 7 560 7 460 7 370 7300 7 210 7 120 .7 020 6 920 6 840 6 770 6 710 6 650 6 590 6 560 6 480 6 370 6 280 6 170 6 090 6 010 5 930 5 880 5 820 5780 5 730 5 690 5 660 5 610 5 58-0 5540 5 490 5460 5 430 5 400 5 370 5 340 5 320 5 300 5 280 5 250 5230 5 200 5 180 5 150 5 150 5 140 5 140 5 180 5 120 12 000 11 910 11 670 11 350 11 030 10670 10 620 10 530 10 380 10 190 10 OOJ 9 790 9 590 9 380 9 230 9 090 8930 8 780 8 630 8 490 8 410 8 310 8 220 8 110 8 010 7 910 7 840 7770 7 700 7 620 7540 7 460 7 320 7 200 7 070 6 970 6 870 6 760 6 640 6 580 6 510 6 460 6 410 6 360 6 340 6 310 6 300 6 290 6 270 6 240 6 210 6 190 6 190 6 150 6 120 6 100 6 080 6060 6 030 6 020 6 000 5 950 5 890 5 840 5 790 5 740 8 000 7 940 7 770 7 580 7 450 7 290 7 110 6 920 6 740 6 620 6 560 6480 6 380 6 270 6 170 6 050 5 970 5 930 5 875 5 820 5 750 5 710 5 690 5 660 5 620 5 570 11 ... 12 . 13 14 15 16 17.... 18.. 19 20.. 21.. 22 23 . 4 25.. 26 27.. 28 29. .. 30. 31.. 32.. 33.... 34.. 35 36 37. 38 39 . 40 42 44 46.. .. Trestles 30 and 60 feet spans, 238,900. 48 50 52.... 54 56... 58 40 and 60 feet spans, 262,900 60... 62 64 66.. 68 70 72 74 76.... 78 80 82 84.. . 86 .........'. 88 90 92 . 94 96 98 100.. . . 105 no 115 120.... 125.. . NOTE For all other classes, the above values to be proportional to the classes. 31 TABLE II. MAXIMUM MOMENTS M. AND END SHEARS S. PER TRACK, PRODUCED BY SPECIAL LOADS ON Two AXLES, 2 23. 1 .a OQ 100,000 LBS. FOR ALL CLASSES UP TO E 40. 3 120,000 LBS. FOR ALL CLASSES OVER E40. | Max. mom., M. Ft.-lbs. Max. shears, S. Lbs. Equiv. unif . load. Max. mom., M. Lbs. Max. shear, & Lbs. Equiv. unif. load. M. Lbs. & Lbs. M. Lbs. S. Lbs. 10.... 11.... 12.... 13.... 14.... 15.... 16.... 17.... 18.... 19.... 30.... 21.... 22.... 28.... 24.... 25.... 26.... 27.... 28.... 29.... 125000 145500 168750 192 300 70000 72700 75000 76900 78600 10000 9620 9370 9100 14000 13220 12500 11830 11220 E40 E35 E30 150000 174600 202500 84000 87250 90000 92300 12000 11550 11250 16800 15850 15000 14200 E50 E45 E41 230760 259300 288000 316800 11000 10600 10250 9900 216100 240000 264000 288250 312500 336850 361 200 8820 8540 8250 7990 7700 7460 7220 94300 96000 97500 13500 12800 12200 80000 81250 82300 83300 84200 10670 10160 9680 9260 8860 345900 375000 404200 433500 98800 100000 101100 9580 9260 8960 8660 11600 11100 10600 85000 85700 86350 86950 87500 88000 88600 88900 8500 8160 7850 7560 7300 7040 6810 6585 102000 102900 10300 9800 385700 410200 434800 459400 484000 508650 533300 558000 582900 7000 6780 6570 6380 6200 6020 5850 5700 5540 462900 ; 492300 8400 8140 103600 9400 89300 6380 PQ tfc * ^fe i-s'SJ: OCOSOOOSOOiOOiClOiOS to .# :pq : *1 o oo 01 * eo o 10 in MIS e *88- 85 *l^' l o5^ a :n sf ^'?i 18 I|S PI 1! RELATIVE COST OF BRIDGES Built Under These Specifications FOR THE DIFFERENT CLASSES OF LOADINGS. The increased cost and weight of metal of bridges of all kinds, built under the requirements of these specifications, will be approximately as follows : For bridges of Class 35 over those of Class E 30 will be E 5 o " N 45 Recommendation. Table III gives a selection of heavy passenger and freight engines in use on the principal railroads of the United States at the end of the Nineteenth century. As far as the effects upon the bridges are concerned, these engines are represented by the typical train loadings of these specifications, E 35 to E 50. That the heavier of these engines is close to the possible maximum, considering the limitations of the permissible cross section of existing railroads and the mechanical details of design and proportions, is not improbable. That the economical tendency towards heavier and heavier engines will in the near future reach the heavier class E 50 upon the most important roads, is to be expected. The cars will also follow the same tendency for many kinds of traffic, as experience justifies the advance. There are now in use self-dumping coal cars of a nominal capacity of 100,000 pounds, which have on four axles a total 34 load of 146,000 pounds (10 per cent, increase over nominal capacity) on a wheel base, for two adjacent cars, of 17 ft. 2 ins. These cars on all ordinary bridges produce strains equivalent to those of E 33. In view of these facts and tendencies, it is recommended that train loading E 35 be the minimum adopted for any rail- road in the United States having a future. Taking into consideration the relative costs of the several classes, as shown above, many railroads will find it best to adopt classes as high as E 40 or E 50. One important system has already adopted Class E 50 for all renewals on its main line. THEODORE COOPER. SPECIFICATIONS ...FOB... Electric Bridges. 1902. C. S. Davis. S^NERAl COPYRIGHTED, 1902, BY C. S. DAVIS, TOLEDO, OHIO. TABLE OF CONTENTS. GENERAL DESCRIPTION. Paragraphs. CLASSES ............................... i L. 20 ................................... 2- 3 L. 30 ................................ ... 4- 5 L. 40 ................................... 6- 7 Recommendation ........................ 8 TYPE .......... ......................... 9 MATERIAL ............... . ............. TO CLEARANCE ..... ...................... Sing!e Track ............................ if Double Track .......................... . u Curves ............. , ................... 13 CURVATURE ........................... 14 END BEAMS ............................ 15 STRINGER SPACING ................... 16 GIRDER SPACING ...................... 17 FLOOR DECK ........................... 18 Rails .................................. ig Cross-Ties ......... ' .................... 20 Guard-Rails ............................ 2 PLANS ................................. ?2 Stress Sheet ..... ....... ................ 23 Working Drawings ...................... 24 Changes ............................... 25 Extras ..................... 26 II PATENTS 27 PROPOSAL 2* Price 29 Time 3 ; J Delays . .. 31 Damage 3- LOADS 33 DEAD LOAD 34- 35 LIVE LOAD 36 L. 20 37 L. 30 .: 3* L- 40 39 WIND LOADS ;|p || I 40 Fixed Load /. 41 Moving Load ... - 42 Additional Section 43- 44 Initial Stress 45 Lateral Struts ; . . -* 40 CENTRIFUGAL FORCE 47 Additional Section .|S Speed 49 LONGITUDINAL STRESSES 50 UNIT STRESSES 51 TENSION 5I COMPRESSION 5 r SHEARING S i BEARING SI BENDING SI ALTERNATE STRESSES ST COMBINED STRESSES 5I TURNTABLE DETAILS 5f VALUES OF AND VALUES OF $ AND in 2 SHEARING AND BEARING VALUE OF RIVETS 54 DETAILS OF DESIGN. LIMITING SIZES. Thickness 55 Angles 56 Bars 57 Columns 5 8 ~ 59 Flanges 60 Pins 61 END BEARINGS. Lead 62 Anchors 63 Pin Bearings . 64 Sliding Knds 65 Roller Ends 66-69 Pier Plate 70 CAMBER. Trusses 71 Plate Girders 72 Framing Out : . . 73 RIVETS 74 NET SECTION 75 ROLLED BEAMS 76 BUILT BEAMS 77 Flanges 78- 79 Web Plate 80 Effective Depth Si Flange Splice 82 Web Splice 83 Stiffeners 84- 87 IV Fillers ......... . ....................... 88- 8g Rivet Spacing ................ ........... 90- 91 Bracing ......................... . ....... 9 2 ~ 93 End Finish ............... . ............. 94- 95 Ends Faced ............................ 06 PIN-CONNECTED BRIDGES. Compression Members ................... 97- 08 Battens .................... . ..... .... 99 L/attice ............................ ... 100 Riveting ........................... ... 101 Pin Plates .......................... 102-103 Pin Holes .......................... . . 10$ Splices .............................. v 105 Eyebars ............................... 106 S iffened Sections ....................... 107 Adjustable Members .................... ioS Stringers ............................... 109 Beams ................................ no Bracing . ............................. t m Top .Struts ____ . ................... ... - 112 Knees ......... .... .................. 1 1 ? Cross Bracing Portals . . VIADUCTS OR TRESTLES. Portals . . .................... ....... i T ^ Bents ................................ \ f ' IT Towers I2O Bearings ............................... I2r Anchorage ............................. 122-12^ Bracing ......................... ....... SWING BRIDGES. Floor System . . . . , 125 Trusses 126 Tunitable . 127 Disc Center 128 Roller Center > 129 Rim Bearing 130-132 Latches 135 End Lifts 134 Rail Lifts 135 End Signa's 136 Machinery 137 Cables 138 Motors 139-140 Material 141 Tender's House : 142 SHOP WORK. FIRST CLASS 143 STRAIGHTENING 144-145 PUNCHING 146 REAMING 147 DRILLING 148 RIVETING , 149 FACING 150-151 FITTING 153 PLANING 153-155 PIN HOLES 156-158 LATHE WORK 159 EYEBARS. Material i6 o Heads !6i Annealing Io *2 VI ADJUSTABLE RODS. Loop Eyes Upsetting 164 Annealing 165 PAINTING. Cleaning 166 Before Assembling 167 Inaccessible Parts 168 Machined Surfaces 16^ Other Parts 170 Application 171-174 FIELD WORK. READY FOR RAILS < ;;-... 175 FLOOR DECK ^ 176 FALSEWORK 177 INTERRUPTING TRAFFIC 4 178 RENEWAL 179 ANCHORAGE , .'. . 180 WATCHMEN i8t LAWS 182 RISKS ; 183 REAMING 184 RIVETING 185 TURNED BOLTS 186 PILOT NUTS 187 PAINTING. Cleaning , . . jgS Rivet Heads ig^ First Coat iV 193 Second Coat !o E Application VII QUALITY OP MATERIAL WROUGHT STEEL. Process 193 Finish 194 Variation 195 Phosphorus 196 Test Pieces 197-200 Ultimate Strength 201 Elastic Limit 202 Elongation 203 Reduction of Area ' 204 Fracture 205 Bending 206 Hard Steel 207 Medium Steel 208 Soft and Rivet Steel 209 Drifting 210 Duplicate Tests 211 Marking 212 Eyebar Tests 213-218 WROUGHT IRON. Grade 219 Test Pieces 220 Ultimate Strength 221-222 Elastic Limit 22 ^ Elongation 224 Bending 225-226 CAST STEEL. Process 227 Phosphorus 22-3 Coupon 22c; Annealing , 230 VIII Blow Holes ->. 231 Ultimate Strength 232 Elastic Limit 233 Elongation /,-: 234 Reduction of Area 2 35 CAST IRON. Grade - ." 236 Coupon 237 Tests ... v 238 PHOSPHOR BRONZE. Composition 239 Coupon 240 Tests 241 BABBITT METAL v .. . 2+2 TIMBER .'.,- 243 PAINT. Oil 244 Red Lead \ 245 First Field Coat 246 Second Field Coat 247 INSPECTION. INSPECTOR , 24$ NOTICE OF ROLLING 249 SURFACE INSPECTION ./ 250 SUBSEQUENT DISCOVERY OF DE- FECTS 251 MARKS ', , ..:; 252 FACILITIES 253 FULL SIZED TESTS 254 MAINTENANCE 255 FIRST PAINTING 256 SECOND INSPECTION 257 SPECIFICATIONS FOR ILlectric Railway Bridges. By C. S. DAVIS. 1902. GENERAL DESCRIPTION. (i) Electric railway bridges shall be classified in ac- eordance with their capacity or loading they will be called upon to carry. In these specifications there will be three general classes L, 20, L 30 and L 40. Intermediate or heavier classes may be used if so desired. L - 20 - (2) Bridges of this class shall be designed to carry a train Of electric railway passenger cars, and also a light freight or express service. The weight of the loaded cars should not exceed 80,000 pounds each, and the length of each car should not be less than 40 feet. (3) NOTE: An 84-ton locomotive (engine and tender) may be used during construction to haul sup- ply trains at slow speeds, or a 56-ton locomotive may be used in regular service. L 3Q (4) Bridges of this class shall be designed ?o carry a train of 80,000 pounds capacity freight cars hauled by an electric motor. It is not intended to in- L.40 Recommendations. Type 2 elude pressed steel cars or cars less than 40 feet in length in this ciass. (5) NOTE; A 1 27-ton locomotive (engine and tender) may be used during construction to haul sup- ply trains at slow speeds, or an 85-ton locomotive may be used in regular service. (6) Bridges of this class shall be designed to carry a train of 100,000 pounds capacity freight cars hauled by an electric motor. It is intended to include pressed steel cars and other cars with a short wheel base in this class. (7) NOTE A 1 70- ton locomotive (enigne and tender) may be used during construction to haul sup- ply trains at slow speeds, or a n 3-ton locomotive may be used in regular service. Material (8) Although loading L 20 is sufficient for the traffic of electric railway lines at the present time, the Author, in view of the rapid development of the service, recommends a loading of not less than L 30. See tables of equivalent loads in the appendix. (9) The type of bridge used wil' depend upon local conditions, but the following wiil be preferred : Spans of 20 feet or less Rolled beams. Spans 20 to 100 feet Plate girders. Spans 100 to 120 feet Riveted trusses. Spans over 120 feet Pin-connected trusses. (10) All timber for ties and guard-rails shall be white oak. All metal shall generally be medium steel, but soft steel, wrought iron, cast steel and cast iron may be used as noted hereafter. -3 Clearance Single Track Double Track Curves (n) All single track through bridges on straight track shall have a clear opening of not less than that shown by the accom- panying diagram. Jv T \ Top of /?&/'/ Curvature End Beams Stringer spacing (12) For double track bridges, the clear width shall be increased by an amount equal to the distance between centers of tracks. (13) When a bridge is on a curve additional c'earance must be provided so that the net clearance shall not be less than given above. Curvature of track and tip of car due to super-elevation of outer rail must both be considered. (14) When a bridge is located on a curve the center line of the bridge must be parallel to the chord of the curve connecting the centers of the track at the ends of the span, and must bisect the middle ordinate of the curve. In double track bridges the center between tracks shall be used instead of center line of track as above. (15) All through bridges shall have end beams to carry the ends of stringers over piers and abutments. (16) When two lines of stringers are used for each 4 track they shall be spaced 6 feet 6 inches apart center to center. When four lines of stringers are used for each track the distance from the center of the track to point mid- way between each pair of stringers shall be 2 feet 6 inches, and they shall be so spaced that the bolt fastening the guard- rail to the stringer shall pass just outside the flange of the outer stringers. Girder Spacing (17) Deck girders, less than 80 feet in length shall be spaced 6 feet 6 inches apart center to center. Deck girders 80 feet or more in length shall be spaced 8 feet apart center to center. Floor-deck (18) The floor-deck, consisting of rails, guard-rails, cross-ties and the fastenings for the same, shall be con- structed as follows: Raik (19) The rails shall be what are known as T rails and shall weigh not less than 70 pounds per yard ; they shall be spiked to each cross-tie with two spikes to each rail. Cross-ties (20) The cross-ties, of white oak, shall be spaced at intervals of not more than 16 inches center to center, and they shall not be less than 7 inches by 8 inches by 9 feet for stringers, or girders spaced 6 feet 6 inches apart and 8 inches by 9 inches by n feet for girders spaced 8 feet apart. They shall be dapped at least 1-2 of an inch over the stringers, but must not be dapped to a thickness less than 61-2 inches. Guardrails ( 2I ) A " uar d-rail, of white oak, shall be used along the outside of each rail, and it shall be notched I inch over the cross-ties and bolted to the stringers through every third tie with a 3-4 inch round bolt. A cast iron washer or clip shall be used under each head, Plans. Sir ess -sheets Working drawings Changes Extras 5 and a cast iron washer and nut lock under each nut. The distance between inner faces of the guard rails shall be 7 feet. (22) The Contractor shall prepare stress-sheets and working drawings upon tracing linen which, upon comple- tion of the work are to become the property of the Railway Company. (23) Before beginning work, the Contractor shall submit for formal approval stress sheets of a uniform size, 18 by 24 inches, showing: (a) Length of span center to center of end bear- ings. (b) Height of truss between centers of chords or distance back to back of flange angles for stringers, beams and girders. (c) Live and dead loads assumed in making cal- culations. (d) Stresses in all members. (e) Sections and cross-sectional areas of all mem- bers. (f) Size of rivets in principal members and re- quired rivet spacing- in the flanges of all stringers, floor beams and girders. (24) Before beginning actual construction at the bridge shops the Contractor shall submit for formal approval a complete set of working drawings of a unir form size, 24 by 36 inches. (25) After the approval of the plans, no changes shall be made without the written consent of the Rail- way Company. (26) No extra charges, due to changes made, shall Patents Proposal Price Time Delays Damage LOADS Dead Load 6 be allowed except as agreed upon in writing at the tinie the changes are accepted. (27) If any patented devices or parts are used, the Contractor shall protect the Railway Company against all claims on account of such patents. (28) All proposals must be accompanied by stress- sheets and an estimate of the weight of each span. (29) The price named in the proposal shall be in Cents per pound of the finished weight of the metal, and shall be for the bridge erected, ready for the rails. The timber guard-rails and cross-ties will be furnished de- livered at the bridge site by the Railway Company but shall be framed and put in place by the Contractor. (30) Each Bidder shall state in his proposal a time in which he can complete the bridge after the acceptance "of his proposal, and the Contractor shall agree to com- plete the bridge in the time mentioned in his proposal. (31) When delays occur, due to causes beyond the control of the Contractor, an extension of time will be granted. However, notice of such delay must be given by the Contractor at the time of its occurrence. (32) If any damage is caused by the failure of the Contractor to complete the bridge in the time agreed upon he shall be liable for all such damage. (33) All bridges shall be proportioned to carry the fol- lowing loads : (34) A dead load consisting of the entire weight of the structure. The weight of the rails, cross-ties, guard-rails and the fastenings for the same shall not be assumed at less than 30x3 pounds per foot of track. (35) The weight of the floor system shall be considered as applied at the loaded chord and the remainder of the dead load as applied equally between the loaded and unloaded chords of the main trusses. Live Load (36) The live load used in the calculations shall be one of the following loadings : L 20 (37) A continuous, uniformly distributed moving load of 2000 pounds per foot of track, and a concen- trated load of 20,000 pounds so placed as to produce the maximum effect in every case. L 30 (38) A continuous, uniformly distributed moving load of 3,000 pounds per foot of track, and a concen- trated load of 30,000 pounds so placed as to produce the maximum eflect in every case. L 40 (39) A. continuous, uniformly distributed moving load of 4,000 pounds per foot of track and a concen- trated load of 40,000 pounds so placed as to produce the maximum effect in every case. Wind I ** 5 (40) All bridges shall be braced to resist the fellow- ling wind loads : Fixed Load (4 1 ) The lateral system for the unloaded chords of a bridge shall be designed for a fixed wind load of 150 pounds, and the lateral system for the loaded chords shall be designed for a fixed wind load of 200 pounds per foot of bridge. Moving Load (4 2 ) The lateral system for the loaded chords of a bridge shall be designed for a moving wind load of 300 pounds per foot of bridge in addition to the fixed wind load. Additional (43) When the stresses from wind loads in the floor beams and chords of the main trusses exceed one- third of the stresses from live and dead loads, addition- al section must be provided for such excess q __ (44) When the top flange of a floor beam acts a a strut for the lateral system, additional section must be provided for such excess. -Initial Stress (45) ^ adjustable lateral rods shall be propor- tioned for an initial stress of 10,000 pounds in addition to the stresses as determined above. Lateral Struts (4^) Lateral struts, in addition to the wind load stresses, shall be considered as taking the resultant from an initial stress of 10,000 pounds on each of the adjustable rods attached to them. ^Centrifugal (47) When a bridge is on a curve, the lateral bracing shall be designed to resist the stresses due to centrifugal force in addition to the stresses due to wind. Additional (4^) To resist the stresses from centrifugal force, -Section . additional section must be provided in the floor beams and in the chords of the main trusses to resist the chord stresses of the lateral truss due to the centrifugal force, (49) Speed for the moving load shall be assumed at 4O-2d miles per hour where d is the degree of cttrva* ture. (50) Due allowance shall be made for the stresses due? Longitudinal Stresses to stopping the load upon the bridge. The coefficient ot friction between the wheels and the rails shall be assumed at 0.20, UNIT STRESSES (51) All members shall be so proportioned that the stresses in pounds per square inch will not exceed those given by the following formula: 10 TFNSTON WROUGHT IRON. SOFT .STEEL. MEDIUM STEEL. Main members f 2 1 { 2 1 f 2 Counters and 8ooo ( 2 -ej ft r 30 J 2 ~ e long hangers Rolled beam 7000 j e j i2 _e| f 2 1 flanges Built beam 8000 ) 2-ej of 2 ) 9000 J ft r 90 * 2 ' f 2 I flanges 8000 1 2-ej ( . ._! 2 ) f 2 ) Deam Hangers Bracing OOOOS v 7000 ( 2 -ej f 2 1 COMPRESSION Chords 9OOO "j (_2 - O ) iiooo[ 2 _ e j f H f 2 1 f M f 2 Posts }*IL_] 5 ' K j jy^ 4 r I 2 ef f*^ r M 2 } 1 r (2 e | 1 | 2 Literal sfrirK f 4 ' ^^ j Scxx) 35^ > 1 2 f hi 2 ) {.taoi^ j 2 ^ SHEARING V ^ V J 4 f 2 * j IICKX) 5 f 1 f) ( 2 ") 5500 / 2 1 Web plates Shon rivet f 2 2 1 5OOO Q > 2 ) Field rivets \ 2 ~ Q \ 6000 2-ej Pins BEARING V _/ i 2 1 5000 2 _Q^ ." -i^e} Shop rivets Ffofd rtvpfe 2-ej 2 I 12000 (a-e J j 2 1 Pins 2-e{ ^b-ej $ 2 ) Rollers : ' f 2 ) Masonry f 2 ] f 2 | f 2 2 \ BENDING Pins 200 ('2-8 \ I5000 |_^j ALTERNATE STRESSES Tension and Compression COMBINED STRESSES Compression and bending Tension and bending TURNTABLE DETAILS Bearing: Bearing: Bearing: Bearing: II 4 in place of i^f in the above formulae and proportion for both compression and tension and use the larger area obtained. A - f V* *? A ~ NOTE r 1 f A C T M D Cast iron wheels on a cast iron track Cast steel wheels on a cast steel track Hard steel rollers on a hard steel track Phosphor-bronze discs on steel 250 D!.^ e 400 400 2500 D . J3 _ Dead load stress 4- Total stress. Maximum Stress of the lesses kind -|- Maximum stress of the greater kind. Distance from centre of inertia to outer edge of the section in inches, Radius of gyration in inches, Length of member in inches. Unit stress from above formulae Required cross sectional area. Total direct compression in pound*. Total direct tension in pounds. Bending moment in inch pounds. Diameter in inches. The same requited areas ivill be obtained b\ diviaing the live load stress by the first factor of the above formulae und the dead load Stress by two times the same factor and adding the ftc'o quot'ents as by the use of the above formulae. 12 (52) Values of and -e '2 2 2-e 2 XH) 2 2 2-e 2-e 2 e 2-e j.ooo 1.005 |.OIO 1-015 ! .O2O i.oooo .200 1.0025 .205, 1.0050 .210 1.0076 .215 I.OIOIJ.22O i. mi ^1.1142 1.1173 1.1205 1.1236 400 405 .410 415 .420 1.2500! 60011.4286 i. 2539 1.605! i. 4337 1.25791.610*1.4388 i. 26181.615! 1. 4440 i.2658f.62oji.4493 .800^ .805 .810" .815 .820 1.6667: 1.6736^ "1.6807: 1.6878 1.6949; .025|l.OI27| .030! i. 01 52] ,.03511.01781 1 .040 11.0204! 1.045! 1.0230! 1.050 1 1.0256! !. 05 5 11.0283! .060 1 1.0309!. i -065 1 1. 0336 1 1.07011.0363! 1 075 1 1 -0390! i .080 1 1, 04.17 1 .085 1 1. 0444! 1.090 [1.047 1 1 i-095 1 1 -499 1 1.100)1.0526! !. 1 05! i. 0554] i.no! 1.0582! .ii5li.o6io| [.126(1.06381 1.125 1-0667! 1.130 1.0695! i. 140! 1.07531 1.145! 1.07821 1. 150! i. 08111 1.1651 1. 0899! !. 170! 1.0929! , 18011.0989 .225 1 1. 1 267 1.425 1 1. 2698 1 .230 1.1299 430^.2739 .23511.1332 -435*1.2780 .240! 1.13641.440! 1.2820! .245 j 1. 1 396(445 11.2862! .250 1 1. 1 429 1.450 1 1. 2903! .255|i.i46ii.455Ti.2945[ 260 1.14941.46011.2987) .26511.15271.46511.3029! .270 1 1 . 1 561 j 47o[i .3072 1 .275] 1. 1594(4751 1.31 15! .280^1. 16281.480! 1.3158! .285^1 .1662 i .485 1 1 .3201 ,29oj.i696f.49o[i.3245J 2951 1-1730 1 495! ^3289 1 .30011.17651.50011.3333! .305! 1.1799! .505! i.3378 [ .310^1.18341.51011.3423! .31511.18691.51511.3468! .32011.19051.52011. .32511.19401.52511. .33011.19761.53011.3605! .335[i.2oi2l. 53511.3652! .34011.20481.54071.3699! .345! 1.20851.545! 1.3746! .35o|i.2i2i .55o|i.3793i .355! 1.21581.55571.3841! .36ok.2i95l.56oi 1.3889! .36511.22321.56511.3937! .370^! 1.22701.570! 1.3986! 375ii. 2308!. 575 11.4035! .380! i. 2346!. 580^1. 4085^ .625 1. i .630] i 63?|i .640 1 1 .645(1 .650)1 .655! i .660 j i -665! i .675! i .680! i .68 5 Ti .690!! 695 1 1 .700!! .7io|i 7i5|i 45451-825! 1.7021; 4598 1.830 IT. 7094 46521.83511.71671 47061.8401.1.7241; 4760'. 845! i. 7316: 4815^.85011.73911 4925 (.86o T i. 7544' 49811.86511.7621! 50381.87011.7699; ,50941.875! 1.7778; .5i5il.88oTi.7857; .52097.88511.79371 .52671.89011.8018; .53261.895^1.8100; 1.190! 1.10501.390! 1.2422!. 590! 14184! Li95li.io8oj.395ii.246i .595) 1.4235 1 73oi i 735! i .740! i 745 1 1 75oli 755! i .760! i 765|i .770(1 775! i 780(1 790! i 795 1 1 ....|. .5504 .91071.83491 .55641.91511.8433 56251.92011.8519: .5686 1.92 5! i. 8605 1 .5748). 930! 1.8692! .58101.935! 1.8779' .58731.94071.8868: 59361 .9451* .8957: .60001.95011.9048' .60641.95511.9139: .61291.96011 9231] .61947.965 T i. 9324! .6260] .970] i. 941 7 i 6327l.975|i.95i2: 6393 1.980 11.9608; .64611.98511.9704: .65291.990^1.9802! 6597!- 995'i. 990 1 |l.OO T 2.OOOO 13 (53) Values of the masonry, and shalfl set the bolts in place, fastening the same with neat Portlarid cenvnit mortar. (181) When necessary the Contractor shall provide watchmen and other safeguards during erection. (182) The Contractor shall comply with a'l laws rind ordinances whenever there are ariy applicable to the work iri execution. (183) The Contractor shall assume all risks of acci- dents or from floods or other causes until the final comple- tion of the work. (184)' When assembling the work in the field, any inaccuracies in the rivet holes must be corrected by reaming, drifting will not be allowed. t)riit pins may only be used td bring the pieces together. (185) All rivets must have lull heads, concentric with the rivet, of a uniform size for the same size of rivet and m'ust be driven so as to completely fill the holies. Loose of poor rivets must be cut out ind replaced. (186) Where it is impossible to drive rivets in the 1 field, turned bolts may be used provided they are tlirned to a driving fit. (187) Pilot nuts shall be used on pins to protect the 1 threads when the pins are being driven. (188) Before applying the field coats of paint, all members shall be cleaned from all blisters, loose paint and dirt. (189) After erection and before applying the Flfst Coat Second Coat Application QUALITY OF MATERIAL Wrought steel Process Finish Variation 33 finishing Coats all heads of field rivets shall he painted with the same material as used for the first field coat. (190) After erection all accessible parts shall re- ceive one coat of "Red Lead Metal Preservative/* (191) After the "Red Lead Metal Preservative'' is thoroughly dry all accessible parts shall receive a second field coat which shall be a high grade graphite or carbon paint. (192) No paint shall be applied in wet or freez- ing weather, or when the metal is not dry. All paint shall be app/ied with good thick brushes (round pre- ferred) having elastic bristles and by skilled painters. All paint must be well rubbed onto the surface and Xvorked into all open spaces and so applied as to com- pletely cover the surface. (193) All wrought steel shall be made by the Open hearth process. (194) The finished product shall be true to size and shape and free from imperfections such as cracks or roughness. When two or more universal mill plates of the same width come together in the finished Work they must be of uniform width and their edges must not be beveled. (195) No greater variation than 2\ per cent, shall be allowed between the estimated and actual weight of any piece of material except for wide plates where the actual weight may exceed the estimated weights by the amounts given in the following table : 34 Width of Plate in Inches. Phosphorus Test Pieces Ultimate Strength Thickness in Inches. | 48 to 75 | 75 to 100. O/er JOG. 1-4 10 per cent. 14 per cent. 18 per cent. 5-16- 8 percent. | 12 percent. 16 per cent. 3-8 7 per cent. 10 per cent. 13 percent. 7-16 6 per cent. 9 per cent. 10 per cent. 1-2 5 per cent. 7 per cent. 9 per cent. 9-l6 4^ per cent. 6J per cent. 8J per cent. 5-8 4 per cent. 6 per cent. 8 per cent. Over 5-8 3-J per cent. | 5 per cent. 6J per cent. (196) The amount of phosphorus shair not ex- ceed .08 per cent, in stee. made in an acid furnace and .04 per cent, in steel made in a basic furnace. (197) The properties of stee! shall be determin- ed from test prices cut from the finished product, rep- resenting each melt. (198) The test pieces, about 12 inches long, shall be planed or turned to a uniform area of not less than J of a square inch for a length of 10 inches. (199) Pieces representing annealed bars may be annealed before testing. (200) When a me!t is rolled into several varie- ties of material a test piece shall be taken from each va- riety. (201) The ultimate strength of the several grades of steel, as determined from the test pieces, shall be within the following limits : Hard steel, 70,000 to 78,000 Ibs. per square inch. Medium steel 62,000 to 70,000 Ibs per square inch. Soft steel, 54,000 to 62,000 Ibs. per square inch. Rivet steel, 50,000 to 58,000 Ibs. per square inch. Elastic Limit Elongation Reduction of area Fracture Bending Hard Steel Medium Steel Soft and Rivet Steel Drifting 35 (202) The elastic limit shall not be less than 55 per cent, of the ultimate strength. (203) The elongation in 8 inches shall not be less than 1 8 per cent, for hard steel. 22 per cent, for medium steel. 24 per cent, for soft steel. 26 per cent, for rivet steel. (204) The reduction of area at the point of frac- ture shall not be less than 35 per cent, for hard steel. 40 per cent, for medium steel. 45 per cent, for soft steel. 48 per cent, for rivet steel. (205) The entire fracture must be silky. (206) A piece of each test piece shall be bent cold 1 80 degrees. (207) No specimen from hard steel shall show any signs of cracks until the diameter of the circle around which the bar is bent becomes less than 3 times the thickness of the specimen. (208) No specimen from medium steel shall show any signs of cracks until the diameter of the circle around which the bar is bent becomes less than the thickness of the specimen. (209) Each specimen from soft or rivet steel shall bend 180 degrees and close upon itself with- out sign of crack or flow on the convex surface. (210) The ductility of medium and soft steel shall be such that a punched hole, the center of which is not more than i inches from the sheared or rolled edge of any piece may be enlarged by drifting to a diam- Duplicate Tests Marking 1 Eydtar Tests - 3 6- eter 50 per cent, greater than the original hole without cracking the specimen at any point. (211) Duplicate tests may be made when the sample fulfills all but one of the requirements. If the second test and the average of the two tests meet all the requirements, the melt may be accepted. (212) All material shall be plainly stamped with a number identifying the melt. (213) The eyebars required for tests and those for the structure shall be made at one time. The test bars to be selected by the Inspector, must be fair aver- age specimens of those which would be classed as good bars acceptable for the work. No bar which, is known to be defective shall be selected for testing. (214) These bars will be required to develope a minimum stretch of 14 per cent, before breaking if of soft steel and 12 per cent, if of medium steel. The elongation to be measured on a gauged length of 10 feet including the fracture. (215) If medium steel is used the bars shall show an ultimate strength of not less than 62,000 9.000 (area :-- perimeter) and if soft steel not less than 54,000 8,000 (area : perimeter). The elastic limit in all cases shall not be less than 55 per cent, of the ultimate strength. (216) In general bars will be required to break in the body. When a bar breaks in the head but de- velopes 14 per cent, elongation before breaking, a second bar shall be selected from the same lot. If this bar breaks in the body and the average elongation of the two bars is not less than 16 per cent., the bars of this lot may be accepted. Wrought Iron Grade Test Pieces Ultimate Strength Elastic Limit Elongation Bending 37- (217) If more than one-third of all the bars tested break in the head, this shall be deemed sufficient cause for the rejection of the entire bill of eybars. (218) Tests of full sized sections that meet the requirements shall be paid for at cost less the scrap value of the material. Tests that fail' to meet the require- ments will be at the expense of the Contractor. (219) All wrought iron shall be be the best doable rolled and double refined iron It must be tbugh fibrous, uniform in quality, thoroughly welded in roll- ing and finished straight and smooth. It must be free from flaws blisters, cinder spots, cracks and imperfect edges. It must be worked from the muck bar and no steel scrap will be allowed in its manufacture. (220) Test pieces shall be prepared the same as for wrought steel. See paragraphs 197 to 200 inclusive. (221) The ultimate strength as determined from the test pieces shall/ no* be less than 50,000 pounds per square inch. (222) Tension tests of full sized bars must show an ultimate strength of at least 52,000 7,000 (area --: perimeter) in pounds per square inch. (223) The elastic limit in no case shall be less than 26,000 pounds per square inch. (224) The elongation in 8 inches shall' be at least 1 8 per cent. (225) All iron must bend co!d 180 degrees to a curve, the diameter of which is not more than twice the thickness of the piece without cracking. When nicked and bent the piece must show no signs of being brittle, but shall bend and break gradually, showing a uniform fibrous fracture. Cast Steel Process Phosphorus Coupon Annealing" Blow holes Ultimate Strength Elastic limit Elongation Reduction of area Cast iron Grade -38- (226) Rivet iron must be capable of being bent double and c 1 osed upon itself, hot or cold, without sign of fracture on the convex surface. When nicked and broken the fracture must be fibrous. (227) All steel castings shall be made by the open hearth process and shall be trre to pattern and of work- manlike finish. (228) The amount of phosphorus shah not ex- ceed .08 per cent. (229) All castings shall be made with a coupon for testing which shalli not be cut off until after the castings have been annealed. (230) All casting's shall be thoroughly annealed. (231) When the bearing surface of any casting is finished, there sha'l be no blow hole visible exceeding one inch in length or exceeding one-half square inch in area. The length of blow holes cut by any straight line shall never exceed one inch in any one foot. (232) The ultimate strength as determined from a f of an inch round turned from the coupon shall be from 65000 to 70000 pounds per square inch. (233) The e^stic limit shall not be less than 40000 pounds per square inch. (234) The elongation shall not be less than 15 per cent, in 2 inches. (235) The reduction of area at the point of frac- ture shall not be less than 20 per cent. (236) All iron castingss shall be made of tough, gray iron and shall be smooth, sound, true to pattern, of workmanlike finish and must be free from b 1 ow holes. 39 Coupon (237) One casting from each melt shall be made with a coupon about one inch square and 15 inches long, for testing. Tests (238) Tests shall be made on the coupons by ap- plying a load midway between supports 12 inches apart. The test bars shall show a deflection of at least .15 inches and develope a fiber stress of at least 43000 pounds per square inch. (239) Castings of phosphor bronze shall contain 88 per cent, copper and 12 per cent, phosphorized tin. The phosphorized tin shall contain 5 per cent, phos- phorus. (240) Each casting shall be made with a coupon from which a one inch cube can be cut for testing. (241) A compression test on this cube shall show an elastic limit of not less than 20000 pounds. The per- manent set on the test cube under a load of 100000 pounds shall not exceed one-s ; xteenth of an inch. (242) A 1 1 babbitt metal shall be composed of 50 parts tin, I part copper and 5 parts antimony. (243) Al! timber sha'l generally be white oak or lon<^ leaf yellow pine. It shall be first-class in all respects, sawed true and of full size and must be free from sap wood and large or loose knots. (244) All oil shall be bored ; linseed oil and shall be of a pa 1 e yePow color, brilliant, limpid, drying well, with a rich luster, and having a pleasant nutty taste. Oil of a greenish or dark color, cloudy or with an uncer- tain taste will not be accepted. Lead (245) All red lead paint shall be high grade. When properly mixed for use and applied to a smooth, vertical surface, it should neither run, separate nor sag. Phosphor bronze Composition. Coupon Tests Babbitt Metal Timber Paint Oil 4 o 1st Field coat (246) The first field coat of paint shall be the "A" brand of "Red Lead Metal Preservative/' made by the Lowe Brothers Co., of Dayton, Ohio. 2nd Field coat (247) The second field coat of paint shall be one of the following: First, Graphite paint made by the Joseph Dixon Crucible Co., of Jersey City, N. J. Second, "Black Metal Coating No. 1407," made by the Lowe Brothers Co., of Dayton, Oh ; o. INSPECTION (248) The Railway Companv wi'l emplov an Inspector Inspectors who will examine and test all material before any work is done upon it. He shall have free access to the mills and shops at all times during- the construct'on of the work and shall have power to reject material when the material or workmanship does not comply with the requirements of these specifications. Notice of rollhg (24$) No material shall be rolted until arrangements have been made for the proper testing and inspection of the same. Surface ( 2 5) Kach and every piece of material shall be sub- Inspection - nutted to examination on all s i des and for that purpose turned over when required. All plates shall be suspended for examination and each piece shall be weighed separately when required by the Inspector. Subsequent ( 2 5 : ) Acceptance of any material by the Inspector discovery s h a ll not prevent its subsequent rejection if found defective of defects after delivery, and such material shall be replaced by and at the expense of the Contractor. (252) Material, when examined at the rolling mills Mirks " by the Inspector, shall when found acceptable, be stamped with his private mark. No work shall be done upon any material that does not bear this mark. Small bars, rods, Facilities Full size tests MAINTE- NANCE First Painting: Second Inspection etc., may be put up in bandies with the Inspector's mark on a metal tag wired to the same. (253) All facilities, labor, tools and instruments ne- cessary for the inspection and testing of all' material in ac- cordance with the letter and intent of these specifications shall be furnished free of expense to the Railway Company. (254) Upon request, the contractor shall be advised as to the number of pieces required for full size tests. (255) The life of a steel bridge depends quite largely upon the care it receives and in view of this fact the Author recommends. (256) That the bridge be repainced whenever the final coat becomes deteriorated and exposes the first field coat of paint. An effort should be made to at all times keep the first field coat protected. Before repaint- ing all surfaces should be thorjughly cleaned, using wire brushes and steel scrapers where necessary. The paint used should be the same as thai used for the sec- ond field coat. A marked difference in the colors of the first and second field coats has been selected in order to more clearly show when the bridge needs painting. (257) That the bridge should be inspected at frequent intervals by some competent person and any necessary repairs be made. Especially should the rivets in the floor system be tested and if any are found loose cut and replace. 42 I APPENDIX. OF THE UNIVERSITY OF 43- Table giving maximum moments (M) and end reac- tions (R) for a train of 80000 pounds street cars each 40 feet long cen er to center of couplings and upon a wheel base of 5 plus 20 plus 5 equals 30 feet and the values of \v based upon M and also upon R where the equivalent load is "w pounds per lineal foot uniformly distributed plus 10 w pounds concentrated, so placed as to give the maximum effect in every case." Span in feet M in foot pounds. R in pounds W has >ed on M B 10 56250 30000 I5OO 2OOO | 12 75210 31670 ^567 J 979 ! 16 II39IO 35000 1582 J 945 2O I53I20 4OOOO 1531 2OOO 24 211670 46670 1604 2121 j 28 277820 5H30 1654 2143 i 32 355600 55000 1701 2H5 1 36 433800 5778o 1721 2063 ' 40 512550 60000 1708 2000 ! 44 59^00 63640 1680 1989 ; 48 670400 67920 1643 1998; 52 749600 7 T 93o I602 1998 ! S6 850000 75720 1598 J 993 : 60 950000 80000 1583 2OOO 64 1070000 83750 !592 1994 ! 68 II9OOOO 89410 1591 2O32 i 72 I32OOOO 93330 1594 2029 76 1460000 96850 1601 2018 1 80 lOOOOOO I 00000 1600 2000 i 84 1780000 103800 1630 1997 ! 88 1960000 107950 1650 J999 ; 92 2I5OOOO 111950 1661 !999 ! 96 235OOOO 117700 1688 2030 IOO 255OOOO I2OOOO 1700 2000 105 28OOOOO 125720 1707 2OTO no 3050000 130900 1706 2014 ' 115 3400000 135900 1752 2013 i 1 20 3900000 140000 1857 2OOO I2 5 39 2 5ooo 144800 1732 1997 ' 150 5650000 170700 1773 2008 1 200 | 9950000 22OOOO 1809 2000 1 While the above table is not necessarily exact, it is close enough to illustrate the value of the loadings selected in these specifications. 44 Tab e giving maximum moments (M) and end reac- tions (R) for a train of pressed steel cars weighing as fol lows: Rated capacity 100000 pounds Excess load 10 per cent 10000 pounds Weight of car 40000 pounds Total load for each car 1 50000 pounds each car having a length of 32^ feet center to center of coup- lings and a wheel base of 5 plus 15 plus 5 equals 25 feet, and the values of w based upon M and also upon R where the- equivalent load is "w pounds per lineal foot uniformly dis- tributed plus 10 w pounds concentrated so placed as to give the maximum effect in every case/' Span in feet M in foot pounds. R in pounds W based on M | R IO 105400 56250 2812 3750 12 I4IOOO 59375 2938 3711 ; 16 254300 71480 3532 3971 2O 328120 84375 3281 4 2l8 24 453 loo 95312 3432 4332 28 600000 103130 3572 4297 32 747700 108980 3595 | 4191 36 895800 117190 3555 4185 40 1044200 126560 348i 4219 44 1162500 i355io 3303 4235 48 1387500 H53io 340i 4274 52 1612500 155770 3446 4327 56 1846900 166070 3472 4370 60 2132500 175000 3554 4375 64 2428000 182810 3613 4353 68 2690600 191360 3597 4349 72 3028100 200520 3657 4360 76 3375000 209700 37oi 4369 80 3750000 219140 3759 4383 84 4162500 229020 3811 4405 88 4575ooo 239060 3851 4427 92 5006200 248230 3887 4433 Q6 5456200 256640 3920 4425 IOO 5906200 265310 3938 4422 105 6468800 276790 3943 4429 no 7078100 288070 3960 4432 H5 7687500 300000 396i 4445 1 20 8343800 312500 3972 4465 125 9421900 324000 4159 4469 150 13078000 381250 4104 4486 200 23109000 495940 4202 4508 While the above table is not necessarily exact, it is close enough to illus rate the value of the loadings selected in these specifications. 45 Table giving maximum moments (M) and end reac- tions (R) for various spans for E 40 loading of Theodore Cooper's Specifications and the values of "w" based on M and also on R where the equivalent load is "w pounds per lineal foot uniformly distributed plus 10 w pounds concen- trated , so placed as to give the maximum effect in every case." Span in feet M in foot pounds. S in pounds W oasea on M| S IO H25OO 6OOOO 3OOO 4OOO 12 160000 70000 3333 I 4375 ! 16 280000 85000 3889 4722 2O | 412500 100000 4125 | 5000 1 24 570400 110800 4321 5036 ! 28 731000 120800 4351 5033 32 9IO8OO 131500 4379 5058 36 IO97OOO 141100 4354 5040 I 40 I3IIOOO 150800 4370 5027 44 | 1543000 161100 4384 5034 48 I 7/6OOO 16(3600 4353 4989 52 2030000 178500 4338 4959 56 2304030 186000 4331 4895 60 2599000 195200 4332 4880 : 64 29IIOOO 205200 4332 4886 68 3247000 215600 434i 4900 72 3584000 226700 4339 4929 ! 76 3942000 238100 4323 4961 ' So 4321000 248400 4321 4968 84 4713000 259000 43*6 4081 88 5I28OOO 269400 4317 49?9 i 92 5552000 279600 43H 4993 96 5988000 289600 4302 4994 IOO 6440000 300000 4293 5000 ; 105 7075000 312200 43T2 4994 no 7774000 324000 4349 4985 "5 8490000 3358oo 4375 4975 1 20 9228000 347400 4394 403 125 9993000 358800 4411 4050 150 I4II2OOO 414670 4428 4879 200 237I2OOO 522000 43 12 4745 Load equivalent to E 40 equals, say 5000 pounds uniform plus 50000 pounds concentrated, based on R and 4500 pounds uniform plus 45000 pounds concentrated, based on M. - 4 6 Table giving a comparison between the loads used 111 these specifications and the tpyical loads shown in Theodore Cooper's Specifications: L 20 equals E 16 (2- 56.8 ton engines followed by 1600- pounds per lineal foot.) L 30 equals 24 (2- 85.2 ton engines followed by 2400 pounds per lineal foot.) 1^37-5 equals 30 (2-106.5 ton engines followed by 3000 pounds per lineal foot.) L4O equals 32 (2-113.5 ton engines followed by 3200 , , pounds per lineal foot.) L 43.75 equals 35 (2-124.2 ton engines followed by 3500 pounds per lineal foot.) L 50 equals E 40 (2-142.0 ton engines followed by 4000 pounds per lineal foot.) L 60 - equals 48 (2-170.4 ton engines followed by 4800 pounds er lineal foot.) L62.5 equals E 50 (2-177.5 ton engines followed by 5000 pounds per lineal foot.) CURVES /LLU37~ffAT/N6 VAL ^ US> //V UN/r S77?5S /CV?/ 1 ^ fr/n Stress U5 I r uLA : : : " : ft 1 50 ISO J70 6- 9' flax Sfress Dead Load 5fn flax Sfress *S5 7 ~ ~i Sta* J7 rm Of <5r(. '&fer, . ^-L > \ -^\^ f . V / J - _ J6O 7 ^ J -SO 7~ n -- -^ - - y J4-O "2 " -x^ , ^ ~g_ ^ J3O ~2* 2 7 ~ ^ r- JEO 7 ^ ' / c ^ JIO 2 p> JOO ^ ^ oe>o 5'- = oso ~~ -^ >_-: !-=.i^ 3 : = 7 070 \ ---] _ I x :.^>. ~: O60 ?::[;;;: ,0or SHEA /?//V<5 STR5S //V LATE6/PDEF WEBS W/THOUT SPECIFICATIONS FOR BRIDGE AT- FOR GENERAL SPECIFICATIONS FOR RAILWAY BRIDGE SUPERSTRUCTURE THE OSBORN ENGINEERING Co OSBORN BUILDING, CLEVELAND, - OHIO. I9O3. TABLE OF CONTENTS. PARA- GRAPHS. I. CLEARANCE . ...... i II. DRAWINGS ........ 2-12 III. FLOOR ......... I3 . l8 IV LOADS ......... I9 . 30 V. UNIT STRESSES ....... 3I _ 4I VI. GENERAL DETAILS . . .... 42-69 VII. I BEAM SPANS ........ 7o _ 7I VIII. PLATE GIRDERS ..-.... 72-83 IX. STRINGERS AND FLOORBEAMS .... 84-88 X TRUSSES AND TOWERS . . . . . .89-104 XI. RIVETED WORK .;.... 105-114 XII. QUALITY OF MATERIALS : A. -Wrought Iron ...... 115-123 B.-Cast Iron ........ I24 c.-Wrought Steel ...... 125-141 D.-Cast Steel ....... I42 143-151 F.-Tiraber ........ I52 XIII. WORKMANSHIP ..... . 153-157 XIV INSPECTION AND TESTS .... 158-161 XV. ERECTION ....... 162-172 XVI. NAME PLATES ....... I?3 XVII. GENERA! ..... . SPECIFICATIONS. BRIDGE OVER. at.... The engineer's general drawings consist of: The Superstructure will consist of spans long. Live load to be..., Paint ' 'first coaV ' to be .... "finish coats" to be. Contractor to erect The entire work to be completed on or before 79. Traffic to be maintained Old Structure to be removed. C Contractor to furnish falsework timber " " and place wooden floor. (3) GENERAL SPECIFICATIONS FOR Railway Bridge Superstructures THE OSBORN ENGINEERING COMPANY Osborn Building. Cleveland, O. 1903. I. CLEARANCE. 1. On a straight track a section, as per diagram given in appendix, must be kept clear in single track through bridges. On a curved track and in double track structures the clear width must be proportionately increased. The distance center to center of the double track is 13 feet. As- suming length of cars 75 feet and spacing of trucks 54 feet, center to center, 2^ inches additional clear width must be provided on the inside. of curves for every inch of elevation of outer rail, on account of tipping of cars. The width from center to center of trusses shall not be less than i-2oth of the span. See Appendix A. II. DRAWINGS. 2. Accompanying these specifications, and forming a part hereof, are general drawings, as enumerated on the second page of these specifications, embodying the infor- mation and data furnished the contractor for his guidance. 3. If general drawings are submitted by the contractor with his proposal, they shall include all stress sheets giving the lengths of spans from center to center of chords; the width of the bridge in the clear and from center to center (5) Engineer's General Drawings. Contractor's General Drawings. Shop Drawings. Drawings. Shop and Order Bills. Size of Drawings. of trusses; the dead, live and other loads on which calcu- lations are based; the dead, live and other load stresses as well as the minimum stresses, and sections for all mem- bers; the sections and areas of lateral and portal struts, lateral and sway rods or angles ; stringers, floor-beams and their connections; sizes of rivets; size, arrangement and character of floor system ; and the class or classes of ma- terial proposed for use in the various parts of the structure. The dead loads assumed for. calculating the stresses shall not be less than the actual weight of the structure. The plus (-)-) sign shall be used to indicate compression stresses and the minus ( ) sign to indicate tension stresses. Stresses shall be given in pounds, and weights of shape metal in pounds per foot of one piece, The plans shall also include such detail drawings as are necessary to express the general intent of the whole work. 4. The contractor shall not, except at his own risk, or- der any material until after the shop drawings have been approved by the engineer. After approval, the contractor shall furnish the engineer, without charge, as many sets of the shop drawings as he may require. 5. After the award of the contract, two complete sets of drawings and details, including stress sheet described above shall be furnished for approval, one set of approved drawings will be returned to the contractor and one will be retained by the Railway Company. One or more sets of drawings may also be required for the use of the inspector. These drawings shall in general be drawn to a scale of one inch to the foot. 6. The contractor shall also furnish the engineer with duplicate copies of all shop and order bills of material and shipping lists of all finished parts, with exact itemized weights of same. 7. All drawings shall be of uniform size twenty-four by thirty-six inches (24"x 36"). They shall be numbered, arranged in systematic order and indexed. (6) 8. On all drawings, dimensions shown in figure shall govern in cases of discrepancy between scale and figures. 9. The contractor shall check all leading dimensions and clearances as a whole and in detail, the fitting of all details, and becomes responsible for the exact position and elevation of all parts of the work ; and the approval of the working drawings by the engineer shall not relieve the contractor of this responsibility. 10. In constructing the work, no variations at any time from the approved drawings, nor from these specifications, shall be made by the contractor, without a written order from the engineer in each case, describing and directing such change. 11. Notes or specifications appearing on the engineer's general drawings are to be construed as superseding and voiding any clauses, or parts of clauses, in these specifica- tions, with which they may conflict. 12. Rivets shall be indicated in accordance with the code shown in the appendix. See Appendix B. III. FLOOR. 13. Cross-ties shall be of the best quality of long leaf southern yellow pine, white or burr oak. They shall have a width of 8" and a depth depending upon the distance be- tween centers of supports, as follows : Spans. to c. Dimensions. Up to 7-0 7'-o" 8'-o" 9'-o" 10 '-o" 12 '-O" 8 X 8 XIO-O 8"x 9"xio'-o" 8"xio"xio'-o" 8"xii"xi2'-o" 8"XI2"XI2'-0" 8"xi4"xi 4 '-o" They shall be spaced 12" between centers, notched y 2 ' f over supports, and every fourth tie shall be fastened to the Manges of stringers by y^" hook bolts flattened at their Dimensions. Contractor Responsible for Accuracy. Variations. Notes. Rivets. Cross-ties. (7) Ribbons. Deck Bridges. Elevation of Outer Rail. lower ends to prevent turning. These bolts shall pass through the raising pieces when used, if practicable. 14. There shall be an 8"x6" ribbon, of the same material as the ties, on each side of each track, with its inner face parallel to and not less than 4' 2" from the center of the track and notched i-%" over each tie, when rails 5" high are used. When rails of less height than 5" are used, the ribbon shall be notched so that its upper surface shall be y 2 " below the top of the rail, or a ribbon of less height may be used. The ribbon shall be fastened to every fourth tie (using the ties secured to the stringers by hook bolts) by ^T ma- chine bolts, having a y%" wrought washer on the top of the ribbon, and a *^" cast washer under the tie. Ribbons shall be spliced over ties by halving horizontally with a lap of 6" Each splice shall be secured by a yfa" bolt at center, the holes of the bolts being 11-16" in diameter. The ribbons must be continued over all piers and abutments. 15. Hook bolts and ribbon bolts are considered to be a part of the metal superstructure. See paragraph 163. 16. The standard spacing for track stringers shall be 6'-6" between centers, and the tracks will be i3'-o" between centers unless otherwise ordered. In double track metal bridges with three trusses the clearance, length of cross ties and spacing of stringers for each track shall be the same as above specified for single track bridges. 17. In single track metal bridges, if the width between centers of trusses does not exceed 12' the cross ties may rest directly on the top chords. If of greater width, floor beams and track stringers shall be used. In plate girders having a span of 5o'-o" or less, the girders shall be 6'-6" c. to c. and in longer spans 8'-o" c. to c. All girders shall be .thoroughly braced laterally and transversely. 18. The outside rail shall be elevated as required by the engineer. This will be effected by wedge-shaped ties or (8) by raising pieces on supports as may be deemed best. If wedge-shaped ties are used, their depth at the inner sup- port shall not be less than for bridges on tangent. IV. LOADS. 19. The weights assumed for calculation shall be as follows : Rails and fastenings 100 Ibs. per lineal foot of track. Timber per foot B. M., Oak, 4-^ Ibs. ; Yellow Pine, 4 Ibs.; Wrought Iron, 31-3 Ibs. per lineal foot for bar i" square. Wrought Steel, 3.4 Ibs. per lineal foot for bar i" square. The dead load shall be assumed as concentrated 2-3 at panel points of loaded chord, and 1-3 at panel points of unloaded chord. 20. The moving load shall, unless otherwise specified, be one of the loadings given in appendix, and specified on the second page hereof. See Appendix C. 21. The effect of impact and vibration shall be added to the maximum strains resulting from the live load, and shall be determined by the following formula : L = L L + D Where I = Impact. L Maximum live load stress. D = Dead load stress. The impact on floor beam hangers shall be assumed at 125%. In computing the effect of impact in cases where the live load and dead load stresses are of opposite nature, the dead load stress shall be assumed to be zero. 22. Where the structure is on a curve, the effect of cen- trifugal force shall be considered and computed by the fol- lowing formula : (9) Static Load. Moving Load. Impact. Centrifugal Force. Longitudinal Forces. Wind Forces. Trestles. W V2 32, 2, r. In which W Live Load, Velocity in feet per second, = Radius of curve in feet, Note. See Osborn's Tables for values of C for various velocities and degrees of Curvature. 23. The longitudinal bracing in metal towers and the attachments of fixed ends of all girders shall be capable of resisting the momentum of train when brought to a sudden stop, the co-efficient of friction of wheels sliding upon rails, being assumed at 0.2. 24. The bottom lateral bracing in deck truss bridges and the top lateral bracing in through truss bridges shall be proportioned to resist a moving force of 150 Ibs. per lineal foot for spans of 200 feet and under, and 0.4 Ibs. per lineal foot for each additional foot in length over 200 feet. 25. The bottom lateral bracing in through truss bridges and the top lateral bracing in deck truss bridges shall be proportioned to resist a moving force of 450 Ibs. per lineal foot for spans of 200 feet and under, and 0.4 Ibs. per lineal foot for each additional foot in length over 200 feet. 26. The lateral bracing in plate girder bridges shall be proportioned to sustain a moving load of 330 Ibs. per foot with 30 Ibs. additional for each foot in depth of girder. Rigid cross frames shall be provided connecting the upper and lower flanges at intervals not exceeding fifteen feet, and all bracing shall be capable of transmitting compression as well as tension stresses. The lateral bracing in deck plate girder bridges will be placed in the plane of the upper flanges. 27. In trestle towers, the bracing and posts shall be pro- portioned to resist wind pressures in addition to the stresses from dead load, live load, centrifugal and traction forces, as follows : (10) ist. A force of 300 Ibs. per lineal foot of structure ap- plied 8' above base of rail, and a wind pressure of 30 Ibs. per sq. ft. on the exposed surfaces of all trusses, girders and towers. 2nd. A wind pressure of 50 Ibs. per sq. ft. on the ex- posed surfaces of all trusses, girders and towers. All trestle bracing shall preferably be composed of shapes designed to transmit compression as well as tension stresses. 28. In determining anchorage for the loaded structure, the trains shall be assumed to weigh 800 Ibs. per lineal foot. 29. Lateral and longitudinal struts shall be proportioned to resist the resultant due to an initial stress of 10,000 Ibs. per square inch upon all rods attached to them when this is in excess of wind stress. 30. Where the effect of a variation of 150 degrees F. is to produce stresses in the structure, the maximum of such stresses in each member shall be provided for. Anchorage Struts. Temperature Stresses. V. UNIT STRESSES. 31. All parts of the structure shall be proportioned by the following unit stresses: (See paragraph 21.) Wrought iron, 13,000 Ibs. per square inch. Soft steel, 15,000 Ibs. per square inch. Medium steel, 17,000 Ibs. per square inch. Tension. 32. Members with square C bearings at both ends, I 2 per Sq. inch. Compression. 36,000 Members with square C bearings at one end f per sq. inch. and pin bearings at 1-| the other, 24,000 f (ii) Members with pin bear- ing's at both ends, Bending. Bearing. Shearing. Field Rivets. Wind Stresses. Alternate Stresses. per sq. inch, 18,000 r~ In which 0=13,000 for wrought iron. 0= 15,000 " soft steel. 0=17,000 " medium steel. 1 length between supports in inches, r = least radius of gyration in inches. 1/r shall not exceed 100 for main members and 1 20 for subordinate mem- bers. 72 NOTE. Values of 2 may be taken from Osborn's Tables. 33. Pins, closely packed, medium steel, 25,000 Ibs. per square inch. 34. Pins 22,000 Ibs. per square inch. Rivets 20,000 Ibs. per square inch. 35. Pins, medium steel 11,000 Ibs. per square inch. " Rivets 10,000 Ibs. per square inch On webs of plate girders soft steel. . 9,000 Ibs. Medium steel . . . 10,000 Ibs. 36. The number of rivets thus found shall be increased 20$ for rivets driven in field. 37. The same permissible stress shall also be used for members subject to wind stresses, centrifugal force and momentum of train. No allowance will be made for the wind stress when combined with stress from dead and live load, unless the combined stress exceed by 25 per cent, the stress from dead and live load only, in which case the combined stress will be used with a unit stress 25 per cent, greater than above given. 38. Members subject to alternate stresses of tension and compression in immediate succession, shall be so propor- tioned that the total sectional area is equal to the sum of the areas required for each stress. (See paragraph 21). The strength of the connections shall be proportionately increased. (12) 39- Members subjected to combined bending and direct stresses must be proportioned for the combined stresses. 40. The timber parts of the structure shall be propor- tioned by the following unit stresses, given in pounds per square inch. SPECIES Trans- verse Loading-. End Bearing 1 . Short Col- umns 1 equai to or less than 12 d. Bearing Across Fibre. Shear Along Fibre i . \Yhite Oak 1400 1400 IOOO 600 300 2. L/ong Leaf Pine 1600 1600 IOOO 350 200 3. White Pine IOOO ICOO 700 200 150 41. Columns whose length exceeds 12 times their least side shall be proportioned by the following formula : C . p Combined Stress. Timber. Timber Columns. 1,000 d 2 Where P= Unit load on column. C= Unit load as given above for short columns. 1= Length of column between supports, in inches. d= Least side of column, in inches. VI. GENERAL DETAILS. 42. When the track is on a curve, both inner and outer Track on trusses or girders are to be alike and to be figured for the Curve ' proportion of the live load given by the formula: m + b w = 2b Where W = load going to either trusses. m = center ordinate to curve. b = width c. to c. of trusses. P = the live load at panel point considered. (13) Net Section. Pins and Rivets. Effective Diameter of Rivets. Minimum Number of Rivets. Pitch of Rivets. Distance from Center of Rivet to Edge of Plate. Distance Between Rivets in Compression Members. Rotters. 43. The net section of any tension member or flange shall be determined by a plane, cutting the member square across at any point. The greatest number of rivet holes which can be cut by this plane, or come within an inch of it, are to be deducted from the gross section. 44. In deducting rivet holes to obtain the net section of riveted tension members, the rivet hole shall be taken with a diameter one-eighth (% ) inch larger than the undriven rivet for rivets with full heads, and one-fourth (*4) inch larger for countersunk rivets in plates ^g" or less in thickness. 45. The effective diameter of the driven rivet shall be assumed the same as its diameter before driving. 46. Where rivets are countersunk the bearing of the head shall not be counted. 47. No connection shall be made with less than three (3) rivets. 48. The pitch of rivets shall not exceed 6 inches, nor be less than three diameters of the rivet. At the ends of compression members the pitch shall not exceed four diam- eters of the rivet for a length equal to twice the depth of the member, and in the flanges of girders and chords carry- ' ing floor the pitch shall not exceed 4 inches. 49. The distance from center of rivet to edge of plate shall not be less than i-% inches, except in bars under 2.-V-2 inches wide. When practicable it shall be at least two diameters of the rivet: It shall not exceed eight times the thickness of the plate. i 50. The distance between rivets for plates strained in compression shall not exceed sixteen times the thickness of plate in line of stress, nor forty times the thickness at right angles to line of stress. 51. All bridges exceeding 80 feet in length shall have hinged bolsters at each end and at one end nests of turned friction rollers of steel bearing upon planed surfaces. The rollers shall not be less than 4" in diameter, and the pres- (14) 58. Heads of eye bars shall be so proportioned as to develop the full strength of the bar. The heads shall be formed by upsetting- and forging, and in no case will weld- ing be allowed. (See paragraph 101.) (15) Least Thick- ness of Plates. Length of Compression Members. sure per lineal inch of roller shall not exceed 500 times the diameter of roller in inches. For bridges under 80 feet in length, one end shall be free to move upon planed sur- faces. 52. No plate or shape shall be less than ^ inch thick for main members, or 5-16 inch thick for wind bracing, lattice bars, etc. 53. Compression members shall not exceed in length 40 times their least width nor 100 times the least radius of gyration tor main members, and 120 times the least radius of gyration for subordinate members. "Main Members" shall include all elements of trusses, posts of towers or bents, and all other members directly acted upon by the live load. "Subordinate Members" shall include lateral systems, sway bracing, and all other members not directly acted upon by the live load. 54. The several segments or parts of a compression member shall be proportionately as strong as the member taken as a whole. 55. Stay plates shall have a thickness of not less than one-fortieth (1-40) the unsupported width. They shall be not less than twelve (12) inches long, nor less than the greatest width of the member. "By length of stay plate is meant the dimension parallel to the axis of the member." 56. Lacing shall never make an angle of less than 60 with the axis of the member. If clear width between seg- ments exceed 12 inches the member shall be double lat- ticed, and the latticing shall never make an angle of less than 45 with the axis of the member. 57. Long vertical tension members will preferably be Tension ..- , Members. stiffened. Stay Plates Lacing. Eye Bars. OF T UNIVEP:. .-.-.. _K,\ Riveted Tension Members. Rods. Loop Eyes. Area of Rods. Screw Ends Washers and Nuts. Bolts. 59. Eye bars must be perfectly straight before boring and bars working together shall be piled and clamped to- gether and bored in one operation. 60. Eye bars shall not be less than five-eighths ( y& ) inch thick, and preferably not less than one-fifth (1-5) the width of the bar. 61. Riveted tension members shall have an excess of section of twenty-five (25) per cent, through pin holes and net section at all other points. Pin plates shall also be pro- portioned for bearing on pins. The material back of pins shall be proportioned for double shear, using for working length the distance from back of pin to end of plate. But the length of plate back of pin shall not be less than two and one-half (2^2) inches. 62. All rods with screw ends shall be upset at the ends so that the area at the root of the thread shall exceed by seventeen (17) per cent, the area of the rod. 63.-. All rods with welded heads must be of wrought iron. 64. When loop eyes are used, the loop must be so de- signed as to develop the full strength of the bar. The eyes must be reamed, and give full bearing on the pins. 65. No lateral or diagonal rod shall be less than one square inch in area. 66. Screw threads shall be cut according to U. S. stand- ard, except in ends of pins. 67. Washers and nuts shall have a uniform bearing. All nuts shall be easily accessible with a wrench for the purpose of adjustment, and shall be effectively checked after the final adjustment. All parts working together or parts of one member of the truss must be equally strained. 68. All bolts must be of neat length and have a washer under head and nut when they are in contact with wood. \Yashers and nuts shall have a uniform bearing. All nuts (16) shall be easily accessible with a wrench for the purpose of adjustment, and shall be effectively checked after the final adjustment. Rivets shall be used in preference to bolts to resist shear- ing stresses. When bolts are unavoidable they must be turned to a driving fit and have a washer under each and every nut. Bearing on threads will not be allowed. Bolts with hexagonal nuts shall in general be used, and round-headed bolts will not be allowed. 69. All spaces which would otherwise permit the lodg- Drainage, ment of water mifst be drained or filled with water-proof material. VII. I BEAMS. 70. I beams will be connected together in groups of two or three for each rail, have a y^ inch sole plate and ^ inch bed plate at each end, and be secured at each end to masonry by two i" anchor bolts, which shall enter the ma- sonry at least 9 inches. Sheet lead y% inch thick to be shipped, boxed, with girders and to be placed between bed plates and masonry. When ends rest on timber wall plates, the loose bed plate can be omitted. 71. When two or three "I" beams form a compound girder they will be connected together at intervals of about 3 feet, by means of vertical I beam separators riveted to their webs. The standard width center to center of "I" girders will be 4 feet n inches and I beam separators will be not less than 20" deep when two beams are used, and 10" deep when three beams are used. There will be a strut at each end, and a system of angle bracing between the girders. VIII. PLATE GIRDERS. Calculation. 72. The length of the span shall be considered as the distance between centers of end bearings, and the depth which shall preferably be not less than i-io of the span, shall be taken as the distance between centers of gravity of the flanges, unless this exceeds the depth from back to back of angles, in which case this latter depth shall be taken. Flanges. 73- The compression flanges of plate girders and beams shall be made of the same gross section as the tension flanges, and they shall be stayed transversely when their length is more than twenty times their width. webs. 74- One-sixth of the web may only be considered as available gross area in each flange when the web sheet is not spliced. All joints shall be spliced by a plate on each side of the web and these plates shall have a double line of rivets on each side of the joint. stiffeners. 75- All web plates shall be stiffened at both edges of end bearings, and at all points of local concentrated load- ings. Intermediate stiffeners shall be used if the ratio of unsupported depth of web to the thickness is greater than fifty. 76. Stiffeners shall be in pairs, and spaced so the shear per foot shall not exceed the safe shear given by the formula. 20000 x 12 t soco r Where t = the thickness of web plate in inches d = the clear distances between supports in inches. NOTE. See Osborn's Tables for safe resistance of web plate against buckling. The maximum spacing of stifleners shall not exceed six (6) feet. 77. There shall be at least two pair of stiffeners over the end bearings, the projecting legs of which shall be as wide (18) as flange angles will permit. These four stiffeners, includ- ing their fillers, shall take care of the maximum end shear. 78. Intermediate stiffeners shall not be less than given below : For Webs 4 feet and under 3^2 x 3 x 5-16 For Webs 4 feet to 7 feet 3>4 x 3^ x ^ For Webs over 7 feet , 5 x 3^ x ^ 79. Fillers, unless ruled otherwise for special cases, shall Fillers, be placed under all stiffeners, the thickness being equal to the thickness of the flange angles. 80. Six inch legs and over will in all cases be connected to the web plates by two rows of staggered rivets, the pitch of rivets shall not be less than 2-^4" nor more than 4-^2". 81. Not less than one-half the total area of the flanges shall be concentrated in the angles, or the largest size angles shall be used. 82. Through plate girders or lattice girders shall be stayed by stiffened gussets at each floor beam or transverse strut. 83. Plate girders shall be cambered y^" for each 25 camber. feet in length, unless otherwise specified. IX. STRINGERS AND FLOOR BEAMS. 84. Stringers shall generally be placed 6 feet 6 inches, center to center; shall be as deep as practicable, consistent with economy, and shall preferably be riveted to the webs of floor beams. The span length shall be taken as the distance between centers of floor beams. 85. When lengths exceed 12 feet or twelve times flange widths, stringers will have their upper flanges connected by a system of angle bracing, angles to be not less than 3-1^x3x5-16, with at least three % inch rivets in connection. Cross frames to be placed near outer ends of end stringers. (19) Bracing will be required in all cases where alignment is on curve. 86. Floorbeams will be riveted to the webs of plate girders or to the posts of through truss bridges, preferably above the pin in the latter case. The span length shall be taken as the distance center to center of trusses. Floorbeam hangers shall be avoided when possible. (See paragraph 21.) 87. All bridges shall preferably have end floorbeams and when distance from center of end floorbeams to back wall equals or exceeds 18", brackets shall be provided in line with stringers. 88. Connection angles of stringers to floorbeams and of floorbeams to truss, shall not be less than 3^x3^x9-16, and the webs of all stringers and floorbeams shall be faced true and square. Unsymmetrical Sections. H-Sections. Top Laterals. X. TRUSSES AND TOWERS. 89. Unsymmetrical chord sections composed of two rolled or riveted channels and one plate shall be so propor- tioned that the centers of pins in abutting members shall be in the same line and the eccentricity may be made sufficient to counteract the bending stress due to the weight of the member or provision must be made for it, as in top chords and end posts. The material shall be concentrated mostly in the channels. 90. H-shaped sections, if exceeding ten inches in depth, shall have tie plates at ends holding them truly square. 91. The top lateral struts shall be of the full depth of the chord and shall be securely riveted thereto. The top lateral rods, if used, shall be attached to the lateral gusset plates, which shall be securely riveted to the top chord. (20) 92. For spans of 200 feet and under, each portal frame shall consist of four angles riveted to the end posts and connected by diagonal latticing. The latticing shall be flat bars if the depth of the portal does not exceed two feet and angles if of greater depth. For spans exceeding 200 feet in length the portal frames /nay consist of top and bottom struts connected by cross braces. 93. In through bridges, when the depth of truss is be- tween 25 and 30 feet, knee braces shall be used at each vertical post; when the depth exceeds 30 feet sub-struts and overhead diagonal rods or lattice struts of angles shall be used at each vertical post. 94. There shall be built or cast steel bolsters at each end of span, securely anchored to the masonry, provision to be made for expansion. Anchor bolts shall be set in Portland cement. (See paragraph 163.) 95. Long tension members shall be clamped together at intersection to prevent rattling. Posts and struts shall be in one length without splice. 96. Struts composed of two channels latticed shall preferably have the webs of the channels vertical with the clear distance between webs such that the radius of gyration of the member with reference to an axis parallel to the webs of the channels shall not be less than the radius of gyration of the channels. Provision must be made for drainage where necessary. 97. The legs of trestle bents shall generally have a batter of one horizontal to six vertical. 98. The bents shall be united in pairs to form towers, and each tower thus formed shall be thoroughly braced in all directions. Lateral and longitudinal struts shall be pro- vided at bottom and at each intermediate joint; also at top in the absence of floorbeams or girders acting as such. 99. Each leg shall be securely anchored to its pedestal, provision being made for expansion. Portals Cross Bracing. Bolsters and Anchors. Long Members. Struts. Towers. (21) Chords. Eyebars. Camber. Eyebars and Pins. 100. If the length of the panel, divided by the least radius of gyration of the top chord is less than the length of span divided by the radius of gyration of the top chords, considered as a trussed column, the latter shall be used in finding the area of top chord sections. 101. Eye bars shall be closely packed, and as nearly par- allel as possible, the greatest allowable inclination of any bar being limited to i inch in 10 feet. (See paragraph 60.) 1 02. Screw ends of pins must project at least ^4" be- yond nuts, to permit upsetting in the field. 103. Trusses shall have just sufficient camber to bring the joints of the compression chord to a true square bear- ing when the truss is fully loaded. Each member of the truss shall be lengthened or shortened in proportion to the street to which it is subject under a full dead and full live load, so that under the full loading each member will be strained to its normal length. 104. The center of bearings of the stressed members are to be considered as the points of application of loads on pins when determining bending moments. The diameter of the pins shall not be less than 4 of the width of widest bar attached. Heads of eye bars must not be less in strength than body of bar. Sort Steel. XI. RIVETED WORK. 105. All holes in tension members of all thicknesses less than three-fourths (%) inch shall be either punched one-eighth (*/&) inch smaller than the rivet required and reamed to one-sixteenth (1-16) inch larger, or they may be drilled from the solid. 1 06. . All holes in tension members of all thicknesses three-fourths ($4) inch or greater shall be drilled from the solid. 107. All holes in compression members of all thick- nesses less than three-fourths (^4) inch shall be punched full size. (22) 1 08. All holes in compression members of all thick- nesses three-fourths (24) inch or greater shall be drilled from the solid. 109. All holes in metal less than three-fourths (%) Medium steel. inch thick shall be either punched one-eighth (*^) inch smaller than the rivet required and reamed to one-sixteenth (1-16) inch larger, or they may be drilled from the solid. no. All holes in metal three-fourths (fy) inch or greater in thickness shall be drilled from the solid. in. Reamed work is not required for fillers, lace bars, transverse, diagonal or lateral bracing, except to make holes true and square to members. 112. When plates are drilled as assembled, they must be separated after being drilled and cleaned of clippings forced between them by the drill. The square shoulders of all rivet holes under rivet heads must have a fillet of one- thirty-second (1-32) inch neatly removed. 113. Every built member or girder must be true and out of wind, neatly finished to length, and field driven rivets of all main girder connections shall be laid out with tem- plates and accurately drilled, so as to pass the rivets cold. 114. Power riveting shall be used wherever possible. All rivets must have neatly capped full heads. Tightening loose rivets by recupping or ' 'setting up" will not be al- lowed; they must be cut out and redriven, whether in shop or field. Rivets must be properly heated and driven to completely fill the holes. No loose rivets allowed. See paragraph 68. Bolt8 XII. QUALITY OF MATERIAL. A. WROUGHT IRON. 115. Wrought iron shall be made by the puddling process or rolled from fagots or piles made up from No. I wrought iron scrap, alone or with muck bar added. (23) Manufacture, Physical Properties. Cold Bending Tests. Nicking Test. Hot Bending Tests. Yield Point. Finish. 116. The minimum physical qualities required shall be as follows: Tensile strength, pounds per sq. inch 48,000 Yield point, pounds per sq. inch... 25,000 Elongation, per cent, in 8 inches 20 117. In sections weighing less than 0.654 pounds per lineal foot the percentage of elongation required shall be 15 per cent. 1 1 8. Cold bending tests shall be made on specimens cut from the bar as rolled. The specimen shall be bent through an angle of 180 degrees by a succession of light blows. 119. When nicked and bent, it shall show a generally fibrous fracture, free from course crystalline spots. Not over 10 per cent, of the fractured surface shall be granular. 1 20. Hot bending tests shall be made on specimens cut from the bar as rolled. The specimens, heated to a bright red heat, shall be bent through an angle of 180 degrees by a succession of light blows and without hammering directly on the bend. 121. If desired, a bar shall be worked and welded in the ordinary manner without showing signs of red-shortness. 122. The yield point shall be determined by the careful observation of the drop of the beam or halt in the gauge of the testing machine. 123. All wrought iron must be practically straight, smooth, free from cinder spots or injurious flaws, buckles, blisters or cracks. As the thickness of bars approaches the maximum that the rolls will produce the same perfection of finish will not be required as in thinner ones. In flat and square bars one-thirty-second (1-32) inch variation either way from the size ordered will be allowed. In round iron one one-hundredth (i-ioo) inch variation either way from the size ordered will be allowed. B. CAST IRON. 124. Castings shall be of tough, gray iron, free from injurious cold shuts or blow holes, and of smooth, work- manlike finish. (24) One sample bar, one inch square, about five feet long, cast in sand mould, shall be furnished from each cast. This sample bar shall be capable of sustaining on a clear span of four and one-half (4.^2) feet, a central load of 500 pounds when tested in the rough bar. C. WROUGHT STEEL. 125. All steel shall be open hearth, made at works of es- tablished reputation, which have been successfully manu- facturing steel for at least one year. 126. If made in an acid furnace, the amount of phos- phorous and sulphur in the finished product shall not exceed eight one-hundredths (.08) of one per cent, and six one-hundredths (.06) of one per cent., respectively. 127. If made in a basic furnace, the amount of phos- phorus or sulphur shall not exceed six one-hundredths (.06) of one per cent. 128. The tensile strength, elastic limit, elongation and reduction of area shall be determined from a standard test piece cut from the finished material and planed or turned parallel for at least ten (10) inches of its length, the piece to have as nearly one-half (J/) square inch sectional area as practicable, and the elongation to be measured on an original length of eight (8) inches. Specimens for bending tests shall be cut from the finished section and shall be of the same form as those used for tensile tests. 129. Three specimens, two for tensile tests and one for bending test, shall be furnished from each melt, except where a melt is rolled into widely varying sections, when each of such widely varying sections shall be represented by at least one test. Where only a small portion of a melt is rolled into the order covered by these specifications, it is left to the discre- tion of the engineer or his authorized representative to reduce the number of tests. Kind. Acid Open Hearth. Basic Open Hearth. Test Pieces. Number of Tests. (25) Full Size Test. Grades. Medium Steel. If the manufacturer so desires, the bending tests may be made on the broken tensile test pieces instead of on speci- mens as specified above. 130. Eyebars shall be of medium steel. Full-sized tests shall show twelve and one-half (i2^4) per cent, elongation in fifteen feet of the body of the eyebar, and the tensile strength shall not be less than 55,000 pounds per square inch. Eyebars shall be required to break in the body, but should an eyebar break in the head, and show twelve and one-half (i2 l / 2 ) per cent, elongation in fifteen feet and the tensile strength specified, it shall not be cause for rejection, provided that not more than one-third (1-3) of the total number of eyebar s tested break in the head. The engineer will notify the contractor of the number of full sized eyebar tests required. All bars which do not meet the requirements of the speci- fications shall be at the expense of the contractor, all others shall be paid for by the purchaser, at the contract price of finished metal work on cars at shops, less the scrap value of the broken bars. (See paragraph 161.) 131. Material which is to be used without annealing or further treatment is to be tested in the condition in which it comes from the rolls. When material is to be annealed or otherwise treated before use, the specimen representing such material is to be similarly treated before testing. 132. rivet. Steel shall be of three grades: Medium, soft and 133. Specimens from finished material, cut to size specified above, shall have an ultimate tensile strength of not less than 60,000 nor more than 70,000 pounds per square inch ; and elastic limit of not less than 35,000 pounds per square inch, and an elongation of not less than twenty- two (22) per cent. This grade of steel to bend cold 180 degrees over a mandrel, the diameter of which is equal to the thickness of the piece tested, without a crack or flaw on the outside of the bent portion. (26) 134- Specimens from finished material, cut to size speci- fied above, shall have an ultimate tensile strength of not less than 52,000 nor more than 62,000 pounds per square inch ; and an elastic limit of not less than 32,000 per square inch; and an elongation of not less than twenty-five (25) per cent. This grade of steel must stand bending cold 180 degrees and close down flat on itself without sign of fracture on convex side of curve. 135. Specimens cut to size specified above shall have an ultimate tensile strength of not less than 50,000 nor more than 60,000 pounds per square inch; an elastic limit of not less than 30,000 pounds per square inch, and an elongation of not less than twenty-six (26) per cent. 136. All blooms, billets or slabs shall be examined for surface defects, flaws or blow holes before being rolled into the finished sections, and such chippings and alterations made as will insure solidity in the rolled sections. 137. Every finished piece of steel shall be stamped with the melt number, and steel for pins shall have the number stamped on the ends. Rivet and lacing steel, and small pieces for pin plates and stiffeners, may be shipped in bun- dles, securely wired together, with the melt number on a metal tag attached. 138. The chemical analysis for carbon, phosphorus and sulphur of each melt must be furnished to the engineer or his representative at the mill, before any of the material rolled from said melt is shipped from the mill. 139. Finished material must present a smooth, clean surface, free from cracks, buckles, flaws, ragged edges, or any other defects, and must be straight throughout and true to section. Soft Steel. 140. A variation of more than two and one-half per cent, from ordered weight will be considered cause for rejection. Rivet Steel. Chippings and Alterations. Branding. Chemical Analysis. Finish. Variation in Weight. (27) Shipments. Quality of Paint. For all plates ordered to gauge, there will be permitted an average excess of weight over that corresponding to the dimensions on the order equal in amount to that specified in following table: WIDTH OF PI,ATE. THICKNESS OF PIRATE. Inch. Up to 75 inches. 75 to 100 inches. Over TOO inches. Per cent. Per cent. Per cent. X 10 14 18 5-i6 8 12 16 ft 7 10 13 7-16 6 8 10 Yz 5 7 9 9-16 4^ 6)4 8> H 4 6 8 Over ^ 3/3 5 61/2 141. Shipments of material from the mills will not be permitted until after the tests have been made. Copies of all shipping invoices must be furnished to the engineer or his representative at the mill as shipments are made. D. CAST STEEL. 142. Steel castings shall be made of a firs^ class quality of open-hearth steel, sound, smooth, true to pattern, and free from blow holes, flaws and warps. All steel castings shall be thoroughly annealed at a temperature sufficiently high to make a blue scale, and when tested in three-quarter (24) inch round turned test pieces, cut from castings, or from extensions cast to the castings, shall show an ulti- mate strength of from 65,000 to 75,000 pounds per square inch, and an elongation of not less than fifteen (15) per cent, in two (2) inches, and including the break. E. PAINT. 143. All paint for use in the "first coat" shall be of the best quality of graphite paint or of carbon primer, of a manufacture acceptable to the engineer. (28) 144- All paint for use in the "finish coats" shall be of a quality and color specified on the second page hereof. 145. All surfaces that are inaccessible after being riv- eted, or after erection, shall have, before assembling or before erection, two (2) coats of pure red lead and boiled linseed oil, mixed in the proportion of eighteen (18) Ibs. of lead to one (i) gallon of oil. All bolts which are to remain permanently in the struc- ture are to be dipped in "first coat," as described above. 146. As soon as shop work is complete, the material shall be thoroughly cleaned from all scale, rust, grease or other foreign matter, and given one coat of "first coat," as described above. 147. Erection marks shall be made on the painted sur- face and not on the bare metal and then oiled over. 148. After erection and before applying the finish coats, the material shall again be retouched and field rivets shall be painted with the "first coat," as described above; the field rivets shall be painted as soon as practicable after driving. 149. All metal work shall, after erection, be thoroughly cleansed from mud, grease or any other objectionable ma- terial that may be found thereon (wire brushes or scrapers shall be used when necessary or required by the engineer), and painted with two (2) coats of "finish coat," as speci- fied above. No painting will be allowed in wet or freezing weather, and all surfaces must be dry when paint is applied. Inaccessible Surfaces. First Coat. Erection Marks. Retouching and Finish Coats. Finishing Coats. 150. All turned or planed surfaces shall be coated with a mixture of white lead and tallow before being exposed to the weather. 151. All paint and oil used for the structure shall be especially purchased, and the contractor will furnish the engineer with copies of all orders for same; and until all Turned and Planed Surfaces. Copies of Orders. (29) such copies have been received by the engineer, no paint shall be applied. F. TIMBER. 152. All timber shall be of the best quality of the kind specified, cut from sound, live timber, free from loose or rotten knots, worm holes, wind shakes or splits, reasonably well seasoned, straight grained, square edged, and free from any defect calculated to impair its strength or dura- bility. Sap wood shall not be allowed in more than ten (10) per cent, of the pieces of one kind, and no piece will be accepted showing sap covering more than one-fourth (/4) the width of the piece on any face at any point, nor more than half the thickness of any plank at its edge, at any point. Annealing. Appearance. XIII. WORKMANSHIP. 153! All workmanship must be strictly first class. 154. All members that may become bent or in any way injured in transportation or erection, or from any cause, must be repaired, straightened and made good to the satis- faction of the engineer. 155. All plates and shapes shall be carefully straightened before the work is laid out, and all work must be finished in a neat and workmanlike manner. The edges of sheared steel plates in main members shall be carefully faced or planed to effectively remove defects caused by shearing. 156. No forging or other work must be performed on any material at a temperature as low as a blue heat, and all steel forged work must be afterward thoroughly and uniformly annealed by heating throughout to a uniform dark red heat and being allowed to cool slowly. 157. Due regard must be had for the neat and attractive appearance of the finished structure; and details of work- manship of an unsightly character will not be allowed. (30) XIV. INSPECTION AND TESTS. 158. All material shall be subject to inspection and tests at mills and shops during the various processes of manu- facture, and free access must be permitted for the Railway Company's engineer or inspectors at any works where ma- terial is in process of manufacture. A notice of at least one week must be given to the Railway Company when its inspector may be on hand for the performance of his duties. 159. All materials and workmanship shall be subject to inspection and rejection of the Railway Company's en- gineer; and all materials condemned by him shall be imme- diately removed from the work. 1 60. The inspection of the work shall not relieve the contractor of his obligation to perform sound and reliable work, as herein provided. And all work of whatever kind which, during its progress, and before it is finally accepted may become damaged from any cause, shall be replaced by good, sound work, satisfactory to the Railway Company's engineer. 161. The contractor shall furnish the engineer or his inspector all necessary facilities for making the tests speci- fied herein. Mill and Shop Inspection. Inspection not to Relieve Contractor. XV. ERECTION. 162. The contractor shall erect the bridge complete, in a thoroughly workmanlike manner and ready for the ties, and to the lines and grades furnished by the Railway Com- pany's engineer. 163. The contractor for superstructure shall furnish and put in place all stone bolts and anchors for attaching the iron or steel work to the masonry. He will drill all the necessary holes in the masonry and set all bolts in neat Portland cement of a brand satisfactory to the -Railway Company's engineer. When the requirements of the con- tract demand that the bolts or anchors be built in the ma- sonry the contractor for the superstructure shall furnish (30 Erection. Anchor Bolts. Lines, Grades, Etc. Unloading. False Work. Permits and Licenses. Damages. said bolts and anchors and deliver them at the bridge site at such time as may be ordered by the Railway Company's engineer, but he will not be required to place them. (See paragraph 15.) 164. All lines and grades are to be given by the Railway Company's engineer. 165. The stakes and marks given by the Railway Com- pany's engineer must be carefully preserved by the con- tractor, who shall give the engineer all necessary assistance and facilities for the establishment of the lines and grades, and the measuring up of the work. 1 66. All material shall be unloaded at the bridge site with care and piled on skids well above the level of the ground. 167. The contractor shall furnish and erect all false work, staging and scaffolding, and all tools and erection plant necessary to do the work thoroughly and expediti- ously, and he shall remove the same as fast as the advance of the work will permit. 1 68. Before placing any false work, the contractor shall submit to the engineer for his approval, duplicate draw- ings, showing the location of all bents, and the placing of falsework other than such as is approved shall not be al- lowed. 169. The contractor shall give to the proper authorities all requisite notices relating to the work in his charge, and obtain all official permits and licenses for temporary ob- structions, and pay all proper fees for same ; and he shall pay "for any other legal charges from city, town or county officers. 170. The contractor shall pay all damages or losses or claims recovered that the owner may be made liable for, and save the owner harmless in all things from any acci- dent which may happen or arise by reason of failure, neglect or refusal on his part or that of anyone in his em- ploy to take all necessary precaution to prevent the same, (32) and also arising from any and all encroachments or tres- passing on the neighboring property. 171. All refuse material and rubbish that may accumu- late during the progress of the work shall be removed from time to time, and upon completion of the work all surplus material, falsework and rubbish shall be removed from the vicinity of the structure as may be directed by the Railway Company's engineer. 172. When the erection is done by the Railway Com- pany, the contractor shall furnish all necessary pilot nuts for erection, to be returned to contractor in as good condi- tion as when received, when erection is completed. Refuse Material and Rubbish. XVI. NAME PLATES. 173. Two name plates of suitable size and design, and which may be required to be of aluminum or bronze, shall be provided and securely fastened at points to be designated by the engineer. The plates shall be inscribed as directed by the engineer. XVII. GENERAL. 174. The structure shall be built under the direction of the engineer in charge, in accordance with the general drawings, and will include all work of any description, whether specifically set forth herein or on the drawings, or not, to make the work herein provided for complete, to the entire satisfaction of the Railway Company. 175. All fees or royalties for any patented invention, article or arrangement that may be used upon or in any manner connected with the construction, erection of the work, or any part thereof, embraced in these specifications, shall be included in the price mentioned in the contract ; and the contractor shall protect and hold harmless the Railway Company against any and all demands for such fees, roy- alties or claims, and before the final payment or settlement is made on account of the contract, the contractor must (33) Patented Devices. Subletting Employees. Changes. furnish acceptable proof of a proper and satisfactory re- lease from all such claims. 176. No part of the work shall be sublet, nor shall the contract for the whole or any portion of the work be as- signed unless by written consent of the Railway Company's engineer. 177. Should any disorderly or incompetent person be employed upon the work, he shall upon notice from the Railway Company's engineer be discharged and not em- ployed again without his permission. 178. The work shall be done substantially in accordance with the accepted plans, details and directions by the en- gineer, and in accordance with these specifications, but the right is reserved by the Railway Company, without incur- ring any liability therefor, to make such changes in the said general or detail plans and in the specifications as its engineer may deem necessary for the convenience, safety and stability of the work, or as shall be deemed advisable or desirable by him, to make the same a satisfactory piece of work. 179. The right is also reserved by the Railway Com- pany, without incurring any liability therefor, beyond the contract price, except as hereinafter provided, to increase or diminish the amount of labor or material, or both, herein provided for, within s'uch limits as shall be deemed neces- sary by said engineer to make said work, when completed, a satisfactory piece of work. 1 80. But if any such change in any of the said general or detailed plans, or in the specifications, shall, in the opin- ion of the Railway Company's engineer, materially increase the actual cost of performing the labor necessary to con- struct the portions of the work thereby changed, beyond what such labor would have cost, if performed without such change, then the contractor shall receive the amount of such increased cost, as determined by the engineer, with ten (10) per cent, thereof additional, such percentage to be for and in lieu of profits ; any decrease in such cost, as (34) determined by the engineer, shall inure to the benefit of the Railway Company. 181. And if by any such change in any of the said general or detail plans, or in these specifications, any material is used in the structure, the cost of which is, in the opinion of the Railway Company's engineer, in excess of that herein provided for, the contractor shall receive such excess of cost, as determined by the said engineer, and ten (10) per cent, thereof additional, such percentage to be for and in lieu of profits; any decrease of such cost, as determined by said engineer, shall inure to the benefit of the Railway Company. 182. The contractor shall make no claim against the Railway Company for damages or losses occasioned by the elements or from any causes for which the Railway Company is not responsible. No claim for extra work not provided for in the plans and specifications will be allowed unless a written order to perform such work shall have been given by the Railway Company's engineer, and all claims for such work shall be presented in writing for settlement in the monthly estimate next after such work shall have been performed. Claims by the contractor for damages by reason of any detention on the part of the Railway Company will not be allowed, but any such detention shall make a corresponding extension of the time for completion of the contract. 183. The work herein provided for shall be commenced upon any part or portion of the same, as the Railway Com- pany's engineer may direct, within ten (10) days after re- ceipt of written notice from the engineer so to do. 184. The work shall be prosecuted continuously and in the most energetic, expeditious and workmanlike manner, with the largest force of all classes of workmen that can be worked to advantage, and the contractor shall supply suffi- cient plant to work at such places and at as many places as the Railway Company's engineer may direct until the whole shall have been completed ; or work upon any part or portion of the structure shall at any time be wholly or partially suspended or discontinued by order of the engineer, when- Claims. Commencement of Work. Prosecution of Work. (35) ever in his opinion the best interests of the owner or the progress of the work upon other parts or portions of the structure may demand it. Completion 185. The entire work herein provided for shall be prose- cuted in such manner that the whole shall be complete and ready for acceptance by the Railway Company at or before the time specified on the first page hereof, or in the event that the contractor fail to complete the work within such specified time, he will be liable for any and all damage which the Railway Company may suffer in consequence of the delay ; provided that any mutual agreement, set forth in the contract of which these specifications form a part, relat- ing to damages for delay of completion after the specified time or to awards for completion before the specified time, shall be and remain in full force and effect. 1 86. If at any time during the progress of the work it should appear by the report of the engineer that the force employed, the quantity or quality of tools or appliances provided, or that the progress or character of the work or material furnished are not respectively such as, in the opinion of the engineer, will insure the completion of the work under this contract within the time specified, or not in accordance with the specifications, then in that case the Railway Com- pany may serve written notice on the contractor and sureties to at once supply such increase of force, appliances or tools, and to cause such improvement to be made in the character of the work or materials, as will be required to make the same conform to these specifications and the requirements of the engineer; and if, on the expiration of three (3) days after the service of such written notice upon the contractor and sureties personally, or by leaving same or mailing same for them at la&t known addresses, the contractor shall have failed to furnish to the Railway Company satisfactory evi- dence of his efforts, ability and intentions to remedy the specified deficiencies, the Railway Company may thereupon erter and take possession of the said work or any part there- of, with tools, materials, plant, appliances, houses, machinery (36) and other appurtenances thereon, hold the same as security for any and all damage or liabilities that may arise by reason of the nonfulfillment of this contract within the time speci- fied, and, furthermore, may employ the said tools and other appurtenances, materials, and such other means as it may deem proper to complete the work at the expense of the contractor, and may deduct the cost of the same from any payment then due or thereafter falling- due to the contractor for this work ; and, in case the contractor shall not complete the work within the time specified, and the Railway Company shall, notwithstanding such failure, permit the contractor to proceed with and complete the said work as if such time had not elapsed, said permission shall not be deemed a waiver in any respect by the Railway Company of any forfeiture or liability for damages or expenses thereby incurred, arising from such non-completion of said work within the specified time, but such liability shall continue in full force against the contractor and his sureties as if such permission had not been given. 187. Approximate estimates will be made monthly by the Railway Company's engineer if requested by the contractor, upon the amount of acceptable material delivered at the bridge site or erected in place, and also reasonable estimates will be allowed at the discretion of the engineer upon ac- cceptable material delivered at the shops in reasonable amounts and proper condition. Ninety (90) per cent, of the amounts of such estimates will be paid in cash within fifteen (15) days after approval of such estimates by the Railway Company provided no legal restraints are placed upon such owner preventing such pay- ment. The remaining ten (10) per cent, will be paid within fifteen days after the final completion and acceptance by the Railway Company of all the work herein specified, provided the same is free from all claims for labor and material under these specifications, which might in any manner become a lien upon said structure or a claim upon the Railway Company. 1 88. The contractor shall be required to comply with all federal, state, city, town or other laws and statutes in force in Estimates and Payments. Comply with All Laws. (37) Special Clauses. Plans and Specifications. Engineer. the locality, and it is understood and agreed that the contract of which these specifications are a part, is made and executed subject to the terms and conditions of any and all such laws. The contractor will be expected to inform himself regarding such laws, and to govern himself accordingly. 189. All the written part of these specifications and any special clauses attached hereto, and referring to this structure, are to be considered as a part hereof, and shall be as carefully noted and as strictly followed as if printed herein. 190. The plans and specifications are intended to be ex- planatory of each other, but should any discrepancy appear, or any misunderstanding arise as to the import of anything contained in either, the interpretation of the Railway Com- pany's engineer shall be final and binding on the contractor ; and all directions and explanations required, alluded to or necessary to complete any of the provisions of these specifi- cations, and give them due effect, will be given by the engineer. 191. The term " engineer," as herein used, is understood to mean the chief engineer in charge of the work, and the work at all times shall be under his control, and the decisions of said engineer upon all questions as to estimates or the determination of the quantity or quality of the work, and on all other questions herein left to his discretion, shall be final and conclusive. The above constitute the specifications referred to in the contract of the undersigned with dated Contracting firm Bv , (38) Ra Appendix B, o CONVENTIONAL SIGNS FOR BRIDGE RIVETS. Shop. Field. / Two Full Heads. Countersunk Inside and Chipped. Countersunk Outside and Chipped. Countersunk both Sides and Chipped. o Flattened to}" high or Countersunk and not Chipped. Flattened to tf" high. Flattened to y % high. Inside. Outside. Both Sides.