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.