STATE OF NEW-YORK.
liEl'LY OF
A. P. ROBINSON, CIVIL ENGINEER,
" TO THE
REPORT OF A W. CRAVEN, •
CHIEF ENGINEER OF THE CROTON AQUEDUCT DEP'T,
IN ANSWER TO A RESOLbTION RELATIVE
TO THE
UNDERGROUND RAILROAD
IN
BROADWAY^ NEW-YORK.
Jlpm-igorh 5
JNO. P. PRALL, PRINTER BY STEAM, NO. 9 SPRUCE-STREET.
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To t\vc Commvttee ow HavYroaAs o£ t\\e Senate
o£ t\ve State o£ Xe-w Yortt:
The communication of A. W. Craven, Esq., Chief Engineer
of the Croton Aqueduct Board, in response to a late resolution
of the Senate, in regard to the proposed Under ground Railway
in New York city, has been placed in my hands. The resolu¬
tion asks his opinion as to the " practicability of constructing a
railroad under Broadway, in the city of New York ; and espe¬
cially as to the effect of the attempt to construct the same, upon
the Croton and other pipes, and the sewers, and the damage, if
any, which may be caused to the city, and to individual property,
owners thereby ; and what precautions ought to be taken in order
to guard against the same, and to provide for the payment of
damages in any legislation having reference to that subject"
Mr. Craven assumes " that the inquiry refers to a railroad
constructed upon the plan and on the route specified in an appli¬
cation made to the Legislature during its last session for author¬
ity to construct an under-ground railroad in Broadway and other
streets, upon which application a favorable act passed both
branches of the Legislature, but failed to receive the signature
of the Governor."
lie assumes also " that the grade location and plan of the
tunnel now proposed, are the same as shown in the report of A.
P. Robinson, C. E., upon the contemplated Metropolitan Railroad
of the city of New York, dated January, 1865."
It seems proper therefore that I should reply to the state-
ments of Mr. Craven.
The resolution of the Senate seems to be somewhat general
in its nature, and the evident object of it was to ascertain his
opinion as to the practicability of coristfUcting miy. tunnel for
the required purposes, without interference with the pipes and
sewers; or if this was unavoidable, the extent of that interfer¬
ence, and the conseipient damage.
4
This I take to be the scope of the inquiry, for I do not
find any reference in the resolution of the Senate to the particu¬
lar plan or grades suggested in my report. I desire to state in
this connection, that the plans and grades suggested by me in
that i-eport "w ere prepared at an early day in the history of this
undertaking, and that they were not put forth dogmatically as
the only plans or the only grades upon which the project could be
carried out, but they were intended merely to demonstrate that
such a project was feasible. To assume therefore that a work
of such magnitude and importance is to be constructed pre¬
cisely in accordance with merely suggestive general plans,
made necessarily in haste from the limited time allowed me,
and that no changes would be made, as subsequent and more
extensive and thorough examinations should develope the exact
nature of the difficulties to be overcome, is, to say the least, a
very gratuitous and disingenuous assumption.
From a careful examination of Mr. Craven's communication
to the Senate, 1 do not learn that the size of the tunnel, its
width, height, form of arch, side walls, or invert, its stations
or the suggested mode of operation, are, in his opinion, imprac¬
ticable, or that these are the features which are to have such
a disastrous effect upon the city. The simple question is there¬
fore one of interference with the water pipes and sewers ; and
the very remarkable and superficial statements made by Mr.
Craven upon these points are all that require attention.
First, as to the water pipes.
Mr. Craven says that at whatever point the work on the
railroad should be in operation, it would at once involve the
necessity of the removal of the main pipes fi'om the section
where the work might be in progress, and then all the direful
consequences of fire, pestilence, litigation, &c., are at once to
ensue. If I can show that his premises are wholly erroneous,
then I think tlie city of New York need take no unusual sani¬
tary precautions on account of the construction of this railroad,
or increase the present number of courts.
The general level of the water mains is eight feet below the
surface of the pavements ; and as they are laid near the centre
of the streets, they are directly over the centre of the proposed
5
tunnel. In laying down a grade line for the arch, such a depth
below the surface of the streets as would keep the whole struc¬
ture below the pipes very naturally suggested itself. Depres¬
sions in Broadway, however, occur, to which it hardly seemed
to me advisable to conform ; and although it is perfectly prac¬
ticable to do so, except at Canal street, yet it forces the grade
to an unnecessary depth at other points, unless the undulations
of the street are followed by the tunnel, which, for many rea¬
sons, is not advisable. It was proposed therefore to excavate
beneath the pipes, and sustain them until the arch could be
built underneath, and only to interfere with them at the special
points mentioned. No citizen of New York city who has seen
immense buildings supported while their foundations have been
taken from under them, and replaced without the slightest frac¬
ture of the walls, will doubt for a moment the practicability of
sustaining a simple pipe, varying from twenty inches to three
feet in diameter.
It would never be necessary to sustain fifty feet at any one
time, for the masonry could follow the excavation at less than
that distance. "We have seen in this city, under the direction
of the engineer who now says that this simple, every-day fact
cannot be accomplished, a very considerable length of these
same pipes sustained while the rock underneath them was
blasted away, and then the whole extent lowered several feet
without serious obstruction to the supply of water.
A very recent feat of the same kind has been accomplished
in Brooklyn with a pipe 12 inches diameter, and without any
special expedients. The earth was carefully removed from under
them for a few inches at a time, leaving, at short intervals, small
ridges sustaining the pipes. These were then gradually work¬
ed out with the edge of a spade, and the whole pipe thus grad¬
ually lowered to its new bed without interruption to the flow of
the water. In Tremont Road, Boston, the mains were raised from
eight to ten feet for a long distance, and without subjecting the
city to any claims for damages that I am aware of. These
cases are mentioned to show how easy it is to deal with the
pipes when necessary, and how readily they may be raised at
all these points, if it be thought best, and that they are not of
6
unfrequeat occurrence. In the construction of the arch under¬
neath them it is not necessary to move them, but simply to hold
them in place. The merest tyro of a builder in New York will tell
you there is nothing wonderful in sustaining a sufficient length
of pipe to permit the prosecution of all the various operations
of construction to be carried on below it until the arch can
be built. These operations, then, it cannot be insisted,, will
produce all the complicated evils so much feared by Mr. Cra¬
ven, and it is not true that at " lohatever points tire' work on
the railroad shall be in operation, it would at once involve the
necessity of the removal of the pipes." If the removal of any
portion is necessary, it is only at the points where the top of
the arch, as shown in the plans, is at less than eight feet below
the carriage way. There are nine such places in the whole
extent of the proposed tunnel between the South Ferry and
Fifty-ninth Street, and a very simple expedient is to lay down
a new main on the side of the street to the extent required for
these changes, completing every portion except the short con¬
necting lengths at each end, before stopping the water in the
old main. The only obstruction then would be during the
comparatively short time which would be required in insert¬
ing these lengths. It is not, therefore, true that the work
upon any portion of this railway would render the removal of
the water-pipes necessary, until after new pipes are laid down ;
and even these slight interruptions are only mode necessary by
the attempt to Jceep the arch of the tunnel as near as possible
to the surface of the streets, and by the particular grade line
laid down in the crude section shown in the report to which he
refers. Very slight modifications of the grade will obviate the
necessity of any interference with the pipes whatever, e.xcept
at Canal Street. By starting at the same level, as shown, at
Bowling Green, and dropping the tunnel three feet lower at
Leonard Street, the crown of the arch would be entirely below
the pipes to that point. Starting at the grade shown at Hous¬
ton Street, and passing eight feet below the surface at Eighth
Street, one continuous ascending grade of less than two feet
per mile will carry the arch to a point eight feet below
Thirty-first Street, avoiding all interference with the water
7
mains from Houston Street to that point. From this to Forty-
fifth Street the whole structure would be so much below the
street that even the sewers need not be disturbed.
At Forty-fifth Street occurs a slight interference, which is
from the arch of a proposed station. This is so easily avoided
that no special mention need be made of it. The only remaining
point is at Fifty eighth Street, where, by dropping the grade
four feet, all necessity for raising the water-pipes is obviated.
These slight changes, which are shown on the accompanying
profile, the practicability of adopting which admits of not the
slightest doubt, will remove all questions of discussion concern¬
ing the water-mains, even should it be admitted that the con¬
struction of the tunnel upon the grades suggested in my report,
will be attended with the incalculable damages which are pre¬
dicted, with so many embellishments, in Mr. Craven's communi¬
cation. But I do not admit anything of the kind; nor will
any sensible person who gives the subject the slightest consid¬
eration believe for one moment that an interruption to the
water-mains less in extent than has occurred frequently in con¬
sequence of their bursting, will subject the city to any claims
for damages.
But there is another ,very simple mode of executing this
work which will readily suggest itself to any one who is not
'desirous of embarrassing the project with a fog of imagi¬
nary difficulties, and of creating vague doubts of its practica¬
bility in the minds of those who are laymen in matters of this
kind, viz., to lay down a new main before touching the old one
at all. It is probable that this will be required in any event
before many years. The present pipes have been laid down
about a quarter of a century, and must be much weakened by
corrosion; besides this, the increased consumption or the re¬
duced capacity of the pipes, in consequence of an accumulation
of oxide and other secretions, creates great complaint in the
lower wards of the city. There can be no doubt that the latter
cause has muclt to do with the want of supply referred to.
Very recent examinations in Brooklyn upon a twelve-inch pipe,
which had been in use three years and two hundred and thirty-
three days, showed an accumulation of the kind spoken of,
8
which reduced the capacity ten per eent. I may here state
that the mains are the grand trunks or arteries of the system,
connecting with smaller distributing pipes at a few special
points. The latter are the veins forming a net-work over
the entire city, crossing and connecting with each other at in¬
numerable intersections, and it is with these only that the
service pipes to adjoining premises are connected. In laying
down a new main, therefore, the only interruption of the sup¬
ply is when the connection is being made with the distributing
pipes, and this interruption is only to a very limited distriet,
from flie frequency of the stop-cocks in them, and the connec¬
tion can be made in any case in two or three hours.
There would seem to be no reason why the main arteries
should not pass through any other parallel route as well as by
Broadway and Fifth Avenue. The new main might be com.
pleted and all its connections made before there is the slightest
interruption with the old main. Mr. Craven referS to a sugges¬
tion that a portion of the inconvenience caused by a diminished
supply, might be obviated by laying down additional mains on
each side of the city as a fe/nporary expedient to supply the east¬
ern and western districts during the disturbance of the central
mains. This, he says, can be done, and he estimates the cost of it
at $952,000. With very great deference to the opinions of Mr.
Craven, I am unable to appreciate the importance of such a sug¬
gestion, for I believe a new and permanent central main can be
laid down for little more than half that cost; and ifit be necessa ■
ry that a new main be put down, I do not look upon the laying
of less than four and a half miles of pipe, varying from twenty
inches to thirty-six inches in diameter, as so Herculean an un¬
dertaking that it is to forbid the construction of a work of such
absolute necessity as the one now proposed. Mr. Craven says
that the laying of the new mains proposed would take about three
years, and the inference is, that to avoid all difiSculty, the work
upon the tunnel could not be commenced until the expiration of
that time. I have to say in reply to this, that new mains, if they
be required, can be laid down concurrently with the construc¬
tion of the railway, without interference with the present
mains until the new ones are complete. Anticipating that
9
there might be fears of obstruction to the water during the pro¬
gress of the works, I suggested in my report a mode of con¬
struction by which all these difiBculties might be obviated.
Subsequent careful consideration of this plan, and consultation
with eminent engineers and conti-actors, fully conhrm my for¬
mer estimate of its entire practicability.
Aside from the question of the water-pipes, there are
other reasons in favor of this mode of constructioa. The ob¬
struction to the streets would never be total; nearly or quite
two-thirds would always be open for traffic when laying either
side, and when the centre was being constructed, whieli could
be done with great rapidity,-the narrow space taken, could
easily be bridged. The large amount of material to be exca¬
vated from the inside of the tunnel would be carried away
without using Broadway for the passage of a single cart-load.
The arch could be brought nearer the surface of the street and
the ingress and egress would be more convenient.
I propose to excavate a pit on one side of the street, as
shown in sketch A, to the depth of the sewers, sustaining the
sides by proper sheathing and braces in the ordinary manner,
leaving two-thirds of the street unobstructed. The remaining
depth may be excavated by the aid of an iron shield, pushed for¬
ward by screws as the work progresses. In this pit can then
be constructed that portion of the masonry shown in the sketch
and as this was carried up, I would completely restore the earth
on both sides of the masonry, and puddle it down. Concurrent¬
ly with the refilling I would lay down the new water main and
sewers, and connect the latter with the sewer pipes of the ad¬
joining premises, and restore the pavements. I would repeat-
this operation on the other side of the street, leaving the cen¬
tre until the sides are finished and the new mains are all laid-
There would then be left about fifteen feet in the centre of the
street to excavate, in order to construct the crown of the arch,
which would be a very simple and speedy operation.
The masonry of the tunnel would then be complete, with
the exception of the invert. The tunnel would be full of earth,
which would be excavated and hauled away through the sta -
tions and at the end entrances. After excavating the interior
10
down to the level of the top of the foundation stones, cross
braces, with timber [stretchers against the side walls may be
inserted, if neceesary, to prevent any danger of movement
while excavating for the invert. After laying this, the braces
may be removed, and the tunnel is complete. In other words,
I propose to construct the masonry first and excavate the inte¬
rior afterwards.
The accompanying sketch, marked A, illustrates the pro¬
posed mode of constructing the sides of the arch ; the sketch
marked B, the central portion, and sketch C the mode of lay¬
ing the invert. The problem is simply to construct the works
shown in sketch A, viz., one of the side walls, the sewer where
required, and the laying of the water main—the gas pipes and
the smaller water pipes would be sustained while the works
progressed under them. I do not hesitate to say that a dozen
able and experienced builders and contractors can be found in
a week's time, who will undertake the work in this manner
under the strongest bonds for its performance. If one side can
be so constructed, the other can, and the completion of the
eentre is the simplest feat possible, for the new mains would be
in operation, and the old ones could be removed as the exca¬
vation progressed.
Mr. Craven states, that I seem to have overlooked the exist¬
ence of the stopcocks and their appurtenances, which necessa¬
rily are placed at various points on the different mains along
the line of the road, and that a glance at the cross section on
his accompanying map, No. 1, will show that if the road be
constructed there will be no room for the stopcocks of the large
mains at any point, without going beyond the limits of the
curbstones, into the space now occupied by private vaults.
A careful inspection of these cross sections, and a careful
measurement of the dimensions of these appurtenances, brings
me, as it must every one who will examine them critically, to
an entirely different conclusion, viz. : that if the tunnel is
placed at the lower grade suggested, they are not in the way at
all at any point, for they do not extend below the pipes ; and
if new mains are laid on the sides of the arch, there is abundant
room. Even if the higher grade, shown in the original profile
11
be taken, there are only four of the exceptional points mentioned
where there might not be depth enough, and unfortunately for
Mr. Craven's statement, it so happens that there are no stop¬
cocks at these localities.
The question of stopcocks in the smaller pipes and of fire-
hydrant connections, which Mr. Craven refers to, has no con¬
nection with the matter at all; for all these pipes are at a less
depth below the pavements than the mains, and no grade for the
tunnel ever suggested, interferes with them at all. If at any of
the few crossing streets, where the top of the arcli is less than
eight feet from the surface, the cross pipes are in the way, they
can readily be carried over or through the arch without difficulty.
But they are only about four feet below the surface, and in but
four to five cases is the arch less than that, below the crossing
streets. The list of stopcocks given by Mr. Craven foots up
sixty-two, and of fire-hydrants seventy-five, on the proposed route ;
and the inference is left to be drawn, that all these are appurtenan¬
ces which involve a difficulty. When it is understood that of this
formidable list ordy fifteen of the stopcocks, and none of the hy¬
drants, are appurtenances of the mains, this serious matter dwin¬
dles to very small proportions.
It is difficult to refer to statements so vague and general as
those contained in Mr. Craven's communication. I have endeav¬
ored to be as specific in my reply as possible. While I appre¬
ciate as fully as any one the vital importance to the city of New
York of a certain and unobstructed supply of water from the
magnificent system of works of which Mr. Craven is the respon¬
sible head, and while I can also understand the increased respon¬
sibility which would be thrown upon him during the construction
of the pi'oposed tunnel, in case alterations are required, and his
consequent reluctance at seeing any works commenced which by
any possibility may make interference necessary, and thereby
increase his responsibility, yet I know that a fair and unbiased
examination of the subject will demonstrate that by the adop¬
tion of the most common and ordinary expedients, such interfer¬
ence will be of too trivial a character to stand for a moment as
a barrier in the way of an improvement, which will do as much
for the welfare and prosperity of the city, and the social com-
12
fort and convenience of its inhabitants, as the Croton Aqueduct
itself.
Second,—the sewers.
Before proceeding to reply to Mr. Craven's statements on
this subject, I desire to present a few of the reasons for my selec¬
tion of the route suggested, as the consideration of the drainage
question was an important if not controlling element in my re¬
commendation.
The Island of Manhattan is about thirteen miles long. From
Grand Street to 130th Street, a distance of about six and a half
miles, the average width is about two miles. From Grand
Street to South Ferry the island harrows rapidly, the distance
from the former to the Battery being considerably less than the
distance across the city at that street. From the southernmost
extremity, the geograpliical centre of the island follows Broad¬
way to the City Hall Park, thence Chatham Street and the
Bowery to Union Square, thence Broadway and. Sixth Avenue
to 130th Street; but the Central Park intervenes, interrupting
Sixth Avenue from .59th Street to 110th Street; and as two-
thirds of the park lies west of the line of Sixth Avenue, Fifth
Avenue becomes central to the district left for population above
59th Street. Broadway, from the City Hall Park to Union
Square, although not exactly the geographical centre, is how-
eveV the great centre of movement north and south. A line of
railway, therefore, under Broadway and Fifth Avenue, is in fact
central to the largest population ; it is the most direct line,
having but two curves in its whole extent to the Harlem River ;
and it avoids all interference with the Central Park, while it
lies directly along side of it, furnishing a direct and convenient
mode of transport to it at any point in its entire length. The
topographical centre or water shed follows the same general
line as the geograpliical centre from South Ferry to 23d Street,
but from 23d Street to Central Park it follows Fifth Avenue.
Between Broadway and the Bowery, and Bayard and Houston
Streets, lies a district comprising a portion of the Sixth, Tenth and
Fourteenth Wards, Avhich drains across Broadway towards the
North River, through a sewer following Canal Street. It occur¬
red to me that if this district could be drained readily into the
13
East River without too great a disturbance of the general system
of sewerage, the route through Broadway would be the one near¬
est fulfilling all the conditions required for a work of the char¬
acter of the proposed tunnel, viz.: It would follow the most
direct route ; would be on the central line of travel, accommo¬
dating the greatest population, and would divide the sewerage
and interfere with it less than upon any other route.
The sewers are constructed nearly in accordance with the
natural drainage of the island; and it is only for short dis¬
tances that they lap over or interlock across Broadway and
Fifth Avenue, except at Canal Street. The heads of the over¬
lapping sewers seldom extend more than a block on either side
of this route. They are at an average depth "of about thirteen
feet below the pavements ; and a tunnel for a railway would
therefore, (unless it should pass entirely below them,) interfere
with the whole system least if it could follow their divide. To
go under them, aside from the additional expense of construc¬
tion, would make access to the railway so inconvenient that it
is not to be thought of for a moment.
Following the natural divide from the City Hall through
Chatham Street, the lowest point in it is found between Pearl
and Rosevelt Streets, which is sixteen feet nine inches above high
water mark. This is the actual water shed at this point. From
this, through Rosevelt Street to the East River, is constructed
a sewer six feet in diameter, the upper end of which at Chatham
Street is at the level of high water. The lower end, at the
river, being entirely below high water, the total inclination or
descent is six feet. There is a descrepancy in the elevation
near the corner of Broadway and Canal Street, as marked on
the plans in the ofSce of the Croton Board. The record there
gives it at sixteen feet six inches, but immediately in front of
the Brandreth House, within a short distance, the record give
twelve feet. The former elevation is evidently a clerical error ;
and as there are but a few inches difference between this point
and the point in S-ont of the Brandreth House, it seemed to me
most probable that it was intended for eleven feet six inches
and I have so assumed it. The depth of the sewer at this point
is nine feet six inches below the pavement, hence it is two feet
14
higher than the head of tha sewer at Rosevelt Street. The
construction of a sewer therefore from Canal Street to Rose¬
velt Street, a distance of about three thousand feet, involving
no unusual difficulties, and for most of the way at less than the
ordinary depth, would drain this district into the East River.
The route then through Broadway and Fifth Avenue becomes
the dividing line. I shall have occasion to refer to this pro¬
posed sewer again.
Upon consideration of the whole sewerage system of the
island, I am satisfied that no other route than Broadway and
Fifth Avenue can be adopted which will not present far greater
difficulties.
The sewers in Broadway are of but little importance. An
inspection of the maps herewith will show their location and
extent. The whole aggregate in that street, from the Bowling
Green to 23d Street, is only about six thousand nine hundred
feet in length, in a distance of about three miles.
They are all three feet wide and four feet high, except the
one between Grand and Canal, which is three and a half by
four and a half feet. The longest continuous sewer is from
Houston to Canal Street, a distance of two thousand four hun¬
dred feet. With this exception, and the one from Canal to
White Street, which is four hundred feet long, they never ex¬
tend more than a block before turning into side streets. I can
conceive no more trivial task in connection with this great un¬
dertaking than the reconstruction of these sewers, by laying
down along side of the tunnel others of a newer and more ap-
pi-oved pattern. No argument is required to demonstrate the
feasibility of this. To ^attempt one would be to insult your
intelligence, and the magnitude of the work as regards cost
cannot be considered as a very onerous burden, when you con¬
sider that sewers of the description required for most of the
way can be constructed for two or three dollars per foot.
The crossing sewers, and those from side streets connecting
with them, are then the only remaining physical obstacles to
be overcome.
These crossings are fifteen in number, leaving out Canal
Street, which is considered elsewhere, and are of size similar to
15
those in Broadway; Mr. Craven estimates the total extent of*
new sewers required, including the latter, to be about ten
miles, and states that many of thein must be turned back in a
direction contrary to the established grades, involving their
entire reconstruction, I am confident that a more careful ar¬
rangement of the changes required will very much reduce this
estimate, and if we deduct the sewers near Central Park drain¬
ing into 59th Street, with which it is not at present proposed to
interfere, and leave out of the computation the new Canal
Street sewer, which I have estimated by itself, it will be found
that my estimate of about five miles is nearly correct. Bnt
whether five miles or ten miles of these small sewers are to
be reconstructed, is not a question of practicability, but one
of dollars and cents—and the difierence may be one hundred
thousand dollars more or less. They may, and many of them
will, run counter to the established grades, but the establish¬
ed grade of a three-feet sewer cannot be considered a very
formidable obstacle. It is a mere paper record, to be reconsid¬
ered when the occasion requires it. One fact I may here
state, that the sowers do now in some cases run counter to the
established grades of the streets, and the changes proposed will
make them concur.
In fact, as a practical question, the alteration of these
grades presents far less difficulty, and involves less inconve¬
nience and interruption in the use of the sewers during their
reconstruction, than in the case of those which are to be rebuilt
on their present grades, for by commencing the work at the new
outlet and working up the inclination, the sewerage would
have ttvo outlets, and would run each way through both the
old and the new sewers, from the point at which work for the
time being would be going on. With proper preparation and
care, the interruption of the connection pipe from any one
building, while the change was being made from the old to the
new sewer, need not be one hour. Every house would have
the old connectTon in full fiow until the new sewer was laid up
to it. There would be no interruption of the sewer at all. If
Mr. Craven's estimate is correct, that ten miles of sewers are
to be reconstructed, then over eighty per cent, are of the class
16
wticb must have their grades changed counter to their present
direction, and every foot of these may he rebuilt without one min¬
ute's stoppage.
The sanitary question is one that might be brought up with
equal propriety, and be invested with equal importance,
whenever a sewer is rebuilt or repaired in any street—for it
must be borne in mind that we have but one such job in each
street, and the ten miles of sewess to be changed extend over
an area five miles long. The repairs and alterations of these
underground outlets are of daily occurrence, and yet prior to
this time it has not been suggested that the health of the city
has been afiected by them. The sanitary question certainly
has not heretofore been considered as a barrier to the great
changes and improvements in the sewerage system of the city,
which we were led to expect when the entire control of those
works should be placed in the hands of the Croton Board. On
the contrary, it was by changes and improvements, involving
precisely the same character of work as is now under discus¬
sion, that the health of the city was to be improved—and
never, until the recent report of Mr. Craven, has the public ,
been informed that all such improvements as have heretofore
been promised are impossible. I submit that this is the only
conclusion that can be drawn from the report.
In Fifth Avenue, above 33d Street, there are no crossing
sewers which are not entirely avoided by the slight modifica¬
tion of the grades of the tunnel which I have heretofore sug¬
gested, and although they might be disturbed, so that their
reconstruction would be necessary for short distances, their
location and grades would not necessarily be changed.
The large sewer in 59th Street, which drains a portion of
Central Park and a small district south of 59th Street, into
the East Kiver, is adverted to by Mr. Craven, and he states
that three thousand seven hundred feet must be rebuilt on the
easterly side of Fifth Avenue. In reply to this I have simply
to say, that when the road progresses beyond 59th Street the
expedient here must be the same as adopted in .similar cases in
the London tunnel, viz., to carry the sewer under the railway,
and drift under the street until the required level be reached
r 17
for its discharge either at other sewers or into the river. The
elevation of this sewer is twenty-three feet above high water.
If carried under the tunnel, its elevation immediately on the
east side would be about twelve feet, and if its outlet at tlie
East River be, as is customary, six feet below high water,
there would be a total fall of eighteen feet. The objection to
placing the sewer so low on account of the difficulty of mak¬
ing the house connections, has not the slightest importance^
for a smaller and less important sewer may be constructed
above it, for all these purposes—dropping into the larger one
with a well-hole, whenever it may be desired to make the
connection,
I have thus, I believe, gone over the ground covered by
Mr. Craven's communication, with the exception of one state¬
ment made by him in regard to the impracticability of drain¬
ing the district east of Broadway at Canal Street, into the East
River, without flashing or constructing it with so high a level
at Broadway, as to render it useless for any but surface drain¬
age. I have alluded to an error in the plan at the office of
the Croton Aqueduct Board. Mr. Craven states that the
elevation of this sewer at Broadway is precisely high water
mark, and that therefore it could have no fall in entering
Rosevelt Street sewer at Chatham Street. Let us admit this
to be correct for the sake of the argument, and that the Rosevelt
sewer must be reconstructed. There would then be six feet
fall between Canal Street and the outlet at the East River, a
distance of flve thousand three hundred feet. This, he urges,
is not a sufficient descent, and then proceeds to set forth the
necessity of flushing; the storing of flood water; a double line of
sewer, and the permanent expense to the city of regular attend¬
ants, and the cost of erecting and maintaining a pumping en¬
gine. All these enormous difficulties and expenses thus sha¬
dowed forth are answered at once by the simple fact, that this
same drainage now discharges into the North River from the
same elevation at Broadway, through Canal Street, a distance
of about four thousand feet ; and through an old flat-bottomed
sewer, acknowledged to be of the worst possible form for
drainage, and yet the necessity for all these preparations of
2
18
reservoirs and pumping engines Las never before been suggest¬
ed. If the mouth of this sewer is at low water mark, the
average descent from Broadway is one and four-fifths inches
per one hundred feet. The average descent of the new sewer
to the East Eiver would be over one and one-third inches per
one hundred feet, and would be far more eflfective with a
cylindrical sewer than is the present descent to the North
River in the old structure. The conclusions which Mr. Cra¬
ven arrives at, it seems to me, are not fairly deducible from
the facts.
The evils of the present system of drainage in New York, and
the necessity of many changes and modifications, has for a long
time been a constant theme with the Croton Board, and finally
these works have recently been placed in the charge of that de¬
partment ; but if we are to be governed by Mr. Craven's conclu¬
sions it is difficult to see how thai Board can ever hope to carry
out the slightest of the improvements suggested heretofore. If
the construction of this railway is impracticable in consequence
of the changes required in the sewers and water pipes, then there
is no power short of that which will eventually destroy all the
works of human hands, which can touch these petty structures
after once being laid in the ground. Right or wrong, sufficient
or insufficient—standing in the way of other and greater works
or not, there must these little tubes lie until they disintegrate,
or if touched for improvement, or to give place to other works,
the city must be subjected to such a multiplicity of claims for
damages, that the sum total can only be ascertained after the
last judgment shall have been rendered in the last court.
The Metropolitan Railway of London met and successfully
overcame difficulties from sewers and water pipes, corn-pared
ivitK which those we have to encounter here are mere child's
play.
It maj be interesting in this connection to know what were
Mr. Craven's statements upon these matters one year ago.
That his opinions could not have been changed by any extended
examinations in the mean time, is shown by his last communi¬
cation, in which he distinctly refers to the limited time given
him.
19
If the difficulties which he makes so conspicuous exist now,
they existed then. It was his business to understand them,
and he had no right to conceal them. Nay, it was his duty as
a public officer to disclose them. He had the opportunity, for
he was called upon, as the following letter will show.
Chief Engineer's Office,
Ckoton Aqpeduct Department, Feb., I860.
Dear Sir : I beg leave to acknowledge the receipt of Mr.
A. P. Robinson's report upon the contemplated Metropolitan
Railway in this city, and also his report on the contemplated
Pneumatic Railway, together with a note from you, asking
whether in mj^ opinion the proposed works would injuriously
affect any of the sewers or other interests committed to our
charge. In reply I beg leave to say, that the works proposed
would, of course, involve the necessity of very considerable
changes in the position of water mains, sewers, and appurte-
nent constructions now occupying space below our street
surfaces; and that during the time required for such altera¬
tion there will be unavoidably much inconvenience felt in the
immediate locality of the work. The inconvenience or dam¬
age will extend bej'ond the immediate locality, just so far
as the water supply and sewerage may depend upon the water
mains and sewers, the operations of which, by reason of the
prosecution of your work, are suspended. The extent of this
damage or inconvenience would, of course, be lessened or in¬
creased according to the manner in which your work would
be carried on.
I have no doubt, however, that the works you contemplate
can be so constructed, and the necessary removals and changes
in the water mains, sewers, &c., be made in such a manner,
that after the whole work is completed the public works will
not be found to have been permanently injured, either in re¬
gard to their concfition or efficiency in operation. As the pro¬
fessional member of the Board, responsible for the good condi¬
tion of the public works referred to, and also for the mainte¬
nance of and uninterrupted enjoyment of their use by the
20
inhabitants, I feel obliged to add that the bill authorizing your
Railway should make provisions, 1st, That the Department
charged with the proper maintenance of the water mains,
sewers and pavements, should have such supervision and con¬
trol over your operations as the public interests might require;
2d, That the city shall be secured against all liabilities for
damages sustained in the prosecution of this work. What I
mean by this is, not only the damage resulting from careless¬
ness or inefficiency of workmen, but all the damage, including
that which is inseparable from the nature of your proposed
work.
As the contemplated operations involve the necessity of the
entire reconstruction of long lines of sewers, with alterations
in the grade and direction of many of them, and also make
necessary a very considerable change in the position of some
of our large water mains, you will, I know, readily concede
tljat temporary inconvenience and damage will be unavoidable
under the most favorable fortune, while any negligence or fail¬
ure might very greatly increase that which, under the.best cir¬
cumstances, will be a very great annoyance. You will, there¬
fore, see that in calling your attention to these points, and
begging you to make proper provision for them in any bill
you may ask of the Legislature, I am doing only what is made
imperative by my offieial responsibility. I am, &c,
A. W. CRAYEN, 0. E.
To H. B. Wilson, Esq.
Care Senator Angel, Albany,
Mr. Craven here requires very reasonable, proper safe¬
guards and guarantees for the public ; and in accordance with
his suggestions, the clauses in the bill, passed last winter, refer-
ing to these points, were prepared, after full consultation with
the other members of the Croton Board, as well as the Corpo¬
ration Counsel.
I believe that the public works to be affected remain in
about the same state now as then. No extensive sewers have
been constructed, nor have any new water mains been laid
down.
21
A work which then presented no serious difficulties to the
mind of Mr. Craven becomes now impracticable; and because
we have a water pipe three feet in diameter, lying eight feet
below the pavements, and a few petty brick sewers, three feet
wide by four feet high; in the route proposed, there is not, in
his opinion, engineering skill enough in the country to con¬
struct this railway. This is the standard as to the ability of
the profession in the United States, gravely put forth by a rep¬
resentative member. I have entertained a pardonable pride
in my profession, and a still higher pride that I am an Ameri¬
can engineer; for although we cannot point to works of the
magnitude and extent of many in the old country, we can
show as brilliant conceptions and as bold achievements as any
that the world can boast; and I should indeed feel humiliated
if I could for a moment believe that you would endorse the
meagre standard here given us, by a refusal to report a bill for
the construction of this work for any of the reasons set forth in
the communication of Mr.. Craven.
I have the honor to be.
Tour obedient servant,
A. P. KOBINSON,
Civil Engineer.
N«w York, Feb. 19,1866.