Transactions of the American Society of Civil Engineers, Vol. LXVIII, Sept. 1910 | Page 3

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