Transactions of the American Society of Civil Engineers, Vol. LXVIII, Sept. 1910
J >> James H. Brace and Francis Mason >> Transactions of the American Society of Civil Engineers, Vol. LXVIII, Sept. 1910AMERICAN SOCIETY OF CIVIL ENGINEERS
INSTITUTED 1852
TRANSACTIONS
Paper No. 1158
THE NEW YORK TUNNEL EXTENSION OF THE
PENNSYLVANIA RAILROAD.
THE CROSS-TOWN TUNNELS.[A]
BY JAMES H. BRACE AND FRANCIS MASON, MEMBERS, AM. SOC. C. E.
In this paper, it is proposed to describe the construction of the
tunnels extending eastward from the easterly extension of the Terminal
Station to the permanent shafts east of First Avenue.
They were located under 32d and 33d Streets from the station to Second
Avenue, and thence, curving to the left, passed under private property
and First Avenue to the shafts, as described in a preceding paper.
Typical cross-sections of the tunnels are shown on Plate XII.[B]
On May 29th, 1905, a contract was entered into with the United
Engineering and Contracting Company for the performance of this work.
This contract provided that work on each pair of tunnels should be
carried on from two shafts. The first, here referred to as the First
Avenue Shafts, were located just east of that avenue and directly over
the line of the tunnels; the other two, called the Intermediate Shafts,
were located on private property to the north of each pair of tunnels in
the blocks between Fourth and Madison Avenues. It was originally
intended to do all the work of construction from these four shafts.
Workings were started both east and west from the Intermediate Shafts,
and those to the west were to be continued to the Terminal Station.
After the change of plans, described in a previous paper, it was decided
to sink a third shaft on each line. These were known as the West Shafts,
and were located between Sixth and Seventh Avenues. Finally, it was
found necessary to build a portion of the tunnels on each line west of
Sixth Avenue in open cut. The locations of the shafts are shown on Plate
XIV.[C]
The First Avenue shafts were built by S. Pearson and Son, Inc., for the
joint use of the two contractors, as described in the paper on the
tunnels under the East River. While the shafts were being sunk, the
full-sized tunnels were excavated westward by the contractor for the
river tunnels for a distance of 50 ft., and top headings for 50 ft.
farther. By this means, injury to the caissons and to the contractor's
plant in the shafts by the subsequent work in the Cross-Town Tunnels was
avoided. The west half of the shaft was for the exclusive use of the
contractor for the Cross-Town Tunnels.
CONTRACTOR'S PLANT.
The method of handling the work adopted by the contractor was, broadly
speaking, as follows: Excavation was usually carried on by modifications
of the top-heading and bench method, the bench being carried as close to
the face as possible in order to allow the muck from the heading to be
blasted over the bench into the full section. The spoil was loaded into
3-yd. buckets (designed by the contractor and hereinafter described), by
steam shovels operated by compressed air, and hauled to the shafts by
electric locomotives. Electrically-operated telphers, suspended from a
timber trestle, hoisted the buckets, and, traveling on a mono-rail
track, deposited them on wagons for transportation to the dock. Arriving
at the dock, the buckets were lifted by electrically-operated stiff-leg
derricks and their contents deposited on scows for final disposal. The
spoil was thus transported from the heading to the scow without breaking
bulk.
When concreting was in progress, the spoil buckets were returned to the
shafts loaded with sand and stone. The concrete materials were deposited
in storage bins placed in the shafts, from which they were fed to the
mixers located at the foot of the shaft about on a level with the crown
of the tunnels. The concrete was transported to the forms in side-dump,
steel, concrete cars, hauled by the electric locomotives.
Electrical power was adopted largely on account of the restricted area
at the shaft sites, where a steam plant would have occupied considerable
space of great value for other purposes. The installation of a steam
plant at the Intermediate Shafts, which were located in a high-class
residential district, would have been highly objectionable to the
neighboring property owners, on account of the attendant noise, smoke,
and dirt, and, in addition, the cost of the transportation of fuel would
have been a serious burden. Except for the forges and, toward the last,
the steam locomotives, not a pound of coal was burned on the work. The
use of the bucket and telpher also eliminated most of the objectionable
noise incident to the transfer of spoil from tunnel cars to ordinary
wagons at the shaft sites. Power plants were installed at the North
Shaft near First Avenue and at the rear of the 33d Street Intermediate
Shaft.
_First Avenue Plant._--Fig. 1, Plate LVIII, is a general view of the
First Avenue plant. The power-house at the corner of 34th Street and
First Avenue supplied compressed air for operating drills, shovels,
pumps, and hoists in the tunnels driven from the river shafts, and in it
three Laidlaw-Dunn-Gordon compressors were installed. The largest was a
32 by 20 by 30-in., two-stage, cross-compound, direct-connected to a
Fort Wayne 480 h.p., 230-volt, direct-current, constant-speed motor run
at 100 rev. per min. This compressor was rated at 2,870 cu. ft. of free
air per minute at a pressure of 100 lb. It was governed by throttling
the suction, the governor being controlled by the pressure in the air
receiver and the motor running continuously at a constant speed. The two
others were of similar type, one was 22-1/2 by 14 by 18-in., rated at
1,250 cu. ft. of free air at a pressure of 100 lb., the other was 16 by
10 by 18-in., rated at 630 cu. ft. They were fitted with 9-ft.
fly-wheels, and were driven at 150 rev. per min. by 105-h.p., General
Electric, 220-volt, compound-wound, direct-current motors running at 655
rev. per min. The larger of these two compressors was driven by two of
the motors belted in tandem, and the smaller was belt-connected to a
third motor. The compressors were water-jacketed and had small
inter-coolers, the water supply for which was itself cooled in a Wheeler
Condenser and Engineering Company's water-cooling tower. The pump and
the blower operating it were electrically driven.
The telphers, used for hoisting muck from the tunnels and for lowering
supplies, were each hung from single rails on a timber trestle, about
40 ft. high, spanning and connecting the two shafts. One machine was
provided for each shaft, and where their tracks crossed 33d Street they
were separated sufficiently to permit the machines to pass each other.
At this point, and covering the street, a large platform was provided,
on which the trucks were loaded and unloaded (Fig. 2, Plate LVIII), and
from which they descended by an incline on First Avenue leading south to
32d Street. The platform also covered practically all the yard at the
South Shaft and materially increased the available working area. The
telphers were built by the Dodge Cold Storage Company, and were operated
by a 75-h.p. General Electric motor for hoisting and a 15-h.p. Northern
Electric Company motor for propulsion. Their rated lifting capacity was
10,000 lb. at a speed of 200 ft. per min.
The carpenter shop and machine-shop, both of which served the entire
work, were conveniently located in small buildings on the loading
platform. In the former the saws were each run independently by small
electric motors suspended under the platform. The heavy forms and form
carriages used in lining the tunnels with concrete were fabricated and
stored on the platform outside. The machine-shop lathes, etc., were all
belted to one shaft driven by an 8-h.p. General Electric motor. Above
the machine-shop was a locker-room and below it on the street level was
the main blacksmith shop for the work. Subsidiary blacksmith shops were
located at each of the other shafts. The storeroom and additional
locker-rooms were located above the power-plant in the North Shaft yard,
and isolated from the other structures was a small oil-house. Additional
storage space was provided by the contractor on 32d Street just west of
First Avenue by renting three old buildings and the yards in the rear of
them and of the Railroad Company's cement warehouse adjacent. Here
electric conduits, pipe, castings, and other heavy and bulky supplies
were stored.
During excavation the headings were supplied with forced ventilation
through 12-in. and 14-in. No. 16, spiral-riveted, asphalted pressure
pipes, canvas extensions being used beyond the ends of the pipes. A No.
4 American Blower, located at the top of each shaft and driven by a
15-h.p. General Electric motor, supplied the air.
[Illustration: PLATE LVIII, FIG. 1.--VIEW OF FIRST AVENUE PLANT.]
[Illustration: PLATE LVIII, FIG. 2.--TELPHER STRUCTURE AND LOADING
PLATFORM, FIRST AVENUE SHAFT.]
[Illustration: PLATE LVIII, FIG. 3.--HEADWORKS AT 33D STREET:
INTERMEDIATE SHAFT.]
[Illustration: PLATE LVIII, FIG. 4.--LOADING SPOIL ON BARGES, 35TH
STREET PIER.]
A concrete-mixing plant was placed in each shaft, the mixer being
located high enough to discharge into cars at about the level of the
springing line of the arch. Above the mixers were the measuring
hoppers set in the floor of a platform which was large enough to carry
half a day's supply of cement. At the South Shaft the cement was
delivered to this floor from the loading platform through a spiral steel
chute; at the North Shaft it was lowered in buckets by the telpher. The
sand and stone were drawn into the hoppers through short chutes from the
base of the storage bins which occupied the remaining height of the
shaft--about 50 ft. At the South Shaft the bins were of concrete and
steel, about 6 by 12 ft. in section, and attached to the central wall of
the caisson. Sand and stone were delivered into them from dump-wagons on
the loading platform. At the North Shaft steel-plate bins were used, and
were supplied with material by the buckets handled by the telpher. The
mixers were No. 5 Smith, belt-connected to 25-h.p. motors, and about 0.8
cu. yd. of concrete was mixed at a batch. The concrete cars were steel
side-dumpers of the Wiener or Koppel type.
In order to be able to continue concreting during the winter, when
neither sand nor stone could be obtained by water, practically all the
space under the loading platforms in the South Shaft yards not occupied
by the blacksmith shop was filled with these materials, which were
placed in storage in the late fall.
_Intermediate-Shaft Plant._--The air-compressing plant was located at
the rear of the 33d Street Intermediate Shaft, and supplied air for
driving the tunnels east and west from the Intermediate Shafts on both
32d and 33d Streets. Two compressors, the same as the large
Laidlaw-Dunn-Gordon machine at First Avenue, were installed here, with a
similar water-cooling tower.
Both shafts were on private property, owned by the Railroad Company, on
the north side of the streets, and each was equipped with two telphers
supported on timber trestles, similar to those at First Avenue. Here,
however, the buckets were placed on wagons standing at the curb, as
shown by Fig. 3, Plate LVIII.
Blowers for ventilation were installed at each shaft, as at First
Avenue, and, after the excavation had proceeded some distance, small
blacksmith shops, for sharpening drill steel and making minor repairs,
were located in the tunnels near the shafts.
The concrete plant in each shaft was similar in arrangement to those at
First Avenue, but the storage bins had wooden walls made of 2 by 4-in.
and 2 by 6-in. scantling nailed flat on each other.
The contractor's office on 33d Street backed up against the 32d Street
shaft site, and the basement was used as a storeroom for supplies for
both shafts.
After the decision to do part of the work between Sixth and Seventh
Avenues in open cut, an 8-in. air main was laid in 33d Street to the
West Shafts, and air was supplied from the Intermediate Shaft for work
on both streets in that neighborhood.
_West-Shaft Plant._--West of Sixth Avenue, between 32d and 33d Streets
and adjacent to the open-cut sections, the Railroad Company obtained
from the Hudson and Manhattan Railroad Company the use of a large area
from which the buildings had recently been removed, and gave the use of
it to the contractor. This was of great value in prosecuting the west
end of the work. The two West Shafts were located in the streets and
were supplied with short timber trestles similar to those at the
Intermediate Shafts. One telpher was taken from each of the Intermediate
Shafts to operate at each of the West Shafts. In addition, a number of
stiff-leg derricks were set up along the open-cut section, and were
operated by Lidgerwood or Lambert air hoisting engines, or by electric
motors, as circumstances dictated. A 15-ton Bay City locomotive crane
was also used along part of the open-cut work on 32d Street.
Several concrete plants were installed at points along the open-cut
section, and were moved from place to place, the same general
arrangement being adopted as at the plants already described. No. 3 and
No. 4 Ransome mixers were used, and were generally set up at about the
level of the top of the arch. The sand and stone storage bins were made
of scantlings spiked together, and were necessarily rather shallow on
account of the proximity of the tunnels to the street surface.
_Thirty-fifth Street Pier._--For the receipt and disposal of materials
at the 35th Street pier, four stiff-leg derricks, operated by electric
hoisting engines, were installed. Two were used in lifting the muck
buckets from the wagons and dumping their contents on the scows for
final disposal (Fig. 4, Plate LVIII); and the other two were fitted with
clam-shell buckets for unloading sand and broken stone from barges and
depositing the materials in large hoppers, from which they were drawn
into wagons for transportation to the various concrete plants. A large
part of the cement (all of which was supplied by the Railroad Company)
was also unloaded at the 35th Street pier and hauled directly to the
work, the surplus being stored temporarily in the Company's cement
warehouses on 32d, 33d and 35th Streets, near First Avenue, from which
it was drawn as required. On the dock was located the main powder
magazine, a small concrete structure. Considerable use was also made of
neighboring piers for unloading electric conduits, lumber, steel, etc.
[Illustration: FIG. 1. SPECIAL STEEL BUCKET
PLAN OF BUCKET
END VIEW
SIDE VIEW OF BUCKET
SECTION AT A-A]
_Tunnel Plant._--The spoil buckets, designed by D. L. Hough and George
Perrine, Members, Am. Soc. C. E., were a novel feature of the work.
These buckets are shown in detail in Fig. 1 and various photographs.
They were of 3 cu. yd. capacity and were split longitudinally, the two
halves being pinned at the apices of the ends. For lifting, they were
suspended from eyes at that point, and, when dumping, trip ropes were
hooked into eyes at the bottom of each side; lifting the trip ropes or
lowering the hoisting rope split the bucket, as shown in Fig. 4, Plate
LVIII, and dumped the contents. They were transported in the tunnel on
flat cars, and in the street on wagons, both cars and wagons being
provided with cradles shaped to receive the bottom of the bucket.
In the tunnels the loading was done with air-operated steam shovels,
four (Model 20) Marion shovels being used at various points of the work.
In Fig. 1, Plate LIX, one of these is shown loading the bucket. The cars
were hauled by General Electric, standard, 10-ton, mine locomotives, the
current for which was taken at 220 volts from a pair of No. 00 copper
trolley wires suspended from the roof of the tunnel. The collector was a
small four-wheeled buggy riding on the wires and connected to the
locomotive by several hundred feet of cable wound on a reel for use
beyond the end of the trolley wire. Two 8-1/2-ton, Davenport, steam
locomotives were also used in 32d Street, toward the end of the work,
after the headings had been holed through and the tunnels would quickly
clear themselves of gas and smoke. The steam shovels were supplemented
by two Browning, 15-ton, locomotive cranes, which handled the spoil in
places where timbering interfered with the operation of the shovels. All
tracks were of 3-ft. gauge throughout and laid with 40-lb. rails.
Practically all the heavy drilling was done with Ingersoll drills (Model
E 52), the trimming being largely done with jap and baby drills. A large
number of pumps were used at various points on the work, and practically
all were of Cameron make, the largest ones at the shaft being 10 by 5 by
13-in. The grout machines were of the vertical-cylinder, air-stirring
type.
SHAFT SINKING.
The sinking of the Intermediate Shafts was the first work undertaken by
the contractor.
The 33d Street Shaft was 34.5 ft. long, 21 ft. wide, and 83 ft. deep.
The rock surface averaged 5 ft. below the ground surface. Sinking was
started on July 10th, 1905, and was completed on October 3d, 1905, the
rock being hard and dry. The average daily rate was 0.73 ft. and an
average of 17.1 cu. yd. were excavated per day, with two shifts of 8 hr.
each. The first shift started at 6 A. M. and the second at 2.30 P. M.,
ending at 11 P. M. These hours were adopted in order to avoid undue
disturbance during the night.
[Illustration: PLATE LIX, FIG. 1.--AIR-OPERATED STEAM SHOVEL USED IN
TUNNEL.]
[Illustration: PLATE LIX, FIG. 2.--TIMBERING IN TOP HEADINGS ABOVE
I-BEAMS.]
[Illustration: PLATE LIX, FIG. 3.--FIRST SECTION OF CONCRETE LINING AT
FIFTH AVENUE.]
[Illustration: PLATE LIX, FIG. 4.--TIMBERING AND RUBBLE MASONRY OVER
I-BEAMS.]
Before blasting the first lift of rock, channel cuts 5 or 6 ft. deep
were made along the sides of the shaft, in order to avoid damage to the
walls of neighboring buildings. Timbering was required for a depth of
only 10 ft. below the surface of the ground.
A drift, 30.6 ft. long, 17 ft. wide, and 27 ft. high, connected the
south end of the shaft with the tunnels. The drift was excavated in
three stages, a top heading and a bench in two lifts. While blasting the
cut in the top heading, there was enough concussion to break glass in
the neighboring buildings. The use of a radialax machine reduced the
concussion somewhat, but it was very quickly abandoned on account of the
length of time required for the drilling.
The construction of the 32d Street Shaft was quite similar to the one on
33d Street. It was 31.5 ft. long, 20.5 ft. wide, and 71 ft. deep. The
depth of earth excavation averaged 19.5 ft. The rock in this shaft was
seamy and not quite as hard or dry as that in 33d Street, and timbering
was required for practically the full depth to the crown of the drift.
Sinking was started on May 15th, 1905, and was completed on October
26th, 1905. The daily average rate was 0.30 ft. in earth and 0.52 ft. in
rock. The drift was excavated in much the same manner as the one in 33d
Street, but the rock being softer the radialax machine was not used.
TUNNEL EXCAVATION.
During the early part of the work, the contractor devoted his entire
attention to the work of excavation. Nearly all the excavation east of
Fifth Avenue was done before any of the lining was placed. At a number
of points west of Fifth Avenue and at a few points to the east the
nature of the rock was such that the two operations had to be done
simultaneously.
_Single-Tunnel Method._--For an average distance of 350 ft. west from
the First Avenue Shafts there were four single tunnels. The rock was
sound and comparatively dry. A top heading of the full size of the
tunnel and about 8 ft. high was first driven. It was drilled by four
drills mounted on two columns, and was blasted in the ordinary way. The
bench was about 13 ft. high. Tripod drills, standing on the bench,
drilled the usual holes, but, owing to the lack of head-room, steels
long enough to reach the bottom of the bench could not be used. Tripod
drills were set as low as possible at the foot of the bench and drilled
lifting holes. These holes were inclined downward from 10 deg. to 15 deg. to the
horizontal, and were spaced to converge at the location of the drainage
ditches. The heading was usually driven from 10 to 20 ft. in advance of
the bench. At this distance a large part of the muck from the heading
was shot backward over the bench. In the single tunnels the muck was
loaded by hand.
_Twin-Tunnel Methods._--From the end of the single-track tunnel westward
to Fifth Avenue on 33d Street, and to Madison Avenue on 32d Street, with
some exceptions, each pair of tunnels was excavated for the entire width
at one operation. Three different methods of work were extensively used.
They were the double-heading method, the center-heading method, and the
full-sized-heading method, and these differed only in the manner of
drilling and blasting. The bench was usually within 10 or 15 ft. of the
face of the heading, and was drilled and fired in the same way as in the
single tunnels. After the installation of the permanent plant, most of
the muck was handled by steam shovels.
In the double-heading method, shown on Plate LVII, the top headings for
each tunnel of the pair were driven separately, leaving a short rock
core-wall between them. The headings were drilled from columns in the
manner described for the single tunnels. The temporary rock dividing
wall between the headings was drilled by a tripod drill on the bench of
one of the headings, and was fired with the bench.
In the center-heading method, also shown on Plate LVII, only one heading
was driven. It was rectangular in shape, about 8 ft. high and 14 ft.
wide. It was located on the center line between the tunnels. In general,
the face was from 6 to 12 ft., or the length of one or two rounds, in
advance of the remainder of the face at the top. The center heading was
drilled by four drills mounted on two columns. By turning these drills
to the side, they were used for holes at right angles to the line of the
tunnels, by which the remainder of the face of the heading was blasted.
By turning the drills downward, the bench holes under the center heading
were also drilled. The center heading explored the rock in advance of
the full-width heading, and gave a good idea as to the care needed in
firing.
For the full-width-heading method, Fig. 2, ten drills were mounted on
five columns set abreast across the face. Holes were drilled to form a
cut near the center line between the tunnels. The remainder of the holes
were located so that they would draw into the cut. The bench was
frequently drilled from the same set-up of columns by turning the
drills downward. In sound rock this method proved to be the most rapid
of any.
Practically all trimming was left until immediately before the
concreting. It was then taken up as a separate operation, but proved to
be costly and tedious, and a hindrance to the placing of the lining.
_Materials Encountered._--All the rock encountered was the familiar
Hudson schist, but it varied widely in its mineral constituents and in
its physical characteristics. In many places where the rock surface was
penetrated, a fine sand was found that was probably quicksand. The
material above the rock in the open-cut sections was mostly sand.
[Illustration: FIG. 2. METHOD OF EXCAVATING WITH FULL-WIDTH HEADING
CROSS-TOWN TUNNELS, MANHATTAN
SIDE ELEVATION
FRONT ELEVATION
PLAN SHOWING POSITION OF COLUMNS FOR DRILLING FACE]
The concurrence of the watercourse, shown on General Viele's map of
Manhattan Island (Plate IX[D]), with the points where difficulties in
the construction of the tunnels were encountered has been noted in a
previous paper.
In all cases where the course of this ancient stream was crossed (except
at its final intersection of 33d Street), the rock was found to be very
soft and disintegrated, a large quantity of water was encountered, and
heavy timbering was required. The construction at these localities will
be taken up later. In addition, disintegrated rock, but of a less
troublesome character, was invariably met under the depressions in the
rock surface developed by the borings from the streets and test holes
from the tunnels. Many of these places required timbering, and no
timbering was elsewhere necessary except at the portals. These
coincident conditions were especially marked in 32d Street, which for a
long distance closely adjoins the course of the former creek.
_Disposal of Spoil._--The materials excavated from the tunnels were
dumped at the 35th Street pier on barges furnished by the Railroad
Company under another contract, and were towed to points near the
Bayonne peninsula where the spoil was used principally in the
construction of the Greenville Freight Yards and the line across the
Hackensack Meadows to the tunnels. Details of this work will be given in
a subsequent paper. After December, 1907, when the excavation was about
85% completed, the contractor furnished the barges and effected the
complete disposal of the spoil.