========+===========+================+===========+==================|
| | Resulting | |
| DESCRIPTION OF STONE. |volume per | |
Mixture.|-----------+----------------| barrel of | Remarks. |
| | |cement, in | |
| Passed | Retained on | cubic | |
| screen. | screen. | yards. | |
--------+-----------+----------------+-----------+------------------|
1:2½:5 | 1½-in. | 3/8-in. | 0.815 | Measured in air |
1:2½:5 | 2½-in. |Run of crusher. | 0.827 | " " " |
1:2½:5 | -- |General average.| 0.808[D]|Measured from plan|
1:2½:5 | 2-in. | 1½-in. | 0.768[E]| " " " |
========+===========+================+===========+==================|
[D] Average for whole of River Tunnel section.
[E] Average from 7,400 cu. yd. in Land Tunnel section.
The sand used was practically the same for the whole of the river tunnel
section, and was supposed to be equal to "Cow Bay" sand. The result of
the mechanical analysis of the sand is shown on Plate XLVI. The stone
was all trap rock. For the early part of the work it consisted of stone
which would pass a 2-in. ring and be retained on a 1½-in. ring, in
fact, the same as used for the land tunnels. This was found to be too
coarse, and for a time it was mixed with an equal quantity of fine
gravel or fine crushed stone. As soon as it could be arranged,
run-of-crusher stone was used, everything larger than 2½ in. being
excluded. About three-quarters of the river tunnel concrete was put in
with run-of-crusher stone. The force was:
_At Manhattan._
1 Foreman @ $3.00 per shift
4 Men on sand and stone cars " 1.75 " "
4 Men handling cement " 1.75 " "
2 Men dumping mixers " 1.75 " "
_At Weehawken._
1 Foreman @ $3.00 per shift
2 Men hauling cement " 1.75 " "
2 Men dumping mixers " 1.75 " "
The average quantity of concrete mixed per 10-hour shift was about 117
batches, or about 90 cu. yd. The maximum output of one of the mixers was
about 168 batches, or 129 cu. yd. per 10-hour shift.
Transportation.
_Surface Transportation._--At Manhattan the stone and sand were received
in scows at the wharf on the river front. For the first part of the
work, the wharf at 32d Street and North River was used, and while that
was in use the material was unloaded from the scows into scale-boxes by
a grab-bucket running on an overhead cable, and then teamed to the
shaft. For the latter part of the work, the wharf used was at 38th
Street and North River, where facilities for unloading were given to the
contractor by the Pennsylvania Railroad Company which was the permanent
lessee of the piers. The material was unloaded into scale-boxes by a
grab-bucket operated by a derrick, and teamed to the shaft. When the
scale-boxes arrived at the shaft they were lifted from the trucks by
derricks and dumped into the bins.
At Weehawken all the stone and sand, with the exception of the stone
crushed on the work, was received by water at the North slip. Here it
was unloaded by a 2-cu. yd. grab-bucket and dumped into 3-cu. yd.
side-tipping cars, which were hauled by a small steam locomotive over
the trestle to the shaft, where they were dumped directly into the bins.
Before beginning the concrete lining, the 2-ft. gauge railway, which had
been used for the surface transportation during the driving of the
iron-lined tunnels, was taken up and replaced by a 3-ft. gauge track
consisting largely of 30-lb. rails. The cars were 3-cu. yd.
side-dumping, with automatic swinging sides. Two steam locomotives which
were being stored at Weehawken (part of the plant from another
contract), were used for hauling the cars in place of the electric ones
used with the 2-ft. gauge railway.
_Tunnel Transport._--The track used in the tunnel was of 2-ft. gauge,
laid with the 20-lb. rails previously used in driving the iron-lined
tunnels. The mining cars (previously mentioned in describing the driving
of the iron-lined tunnels) were used for transporting the invert
concrete, although, for most of the work, dumping buckets carried on
flat cars were used. Several haulage systems were considered for this
work, but not one of them was thought to be flexible enough to be used
with the constantly changing conditions, and it was eventually decided
to move all the cars by hand, because, practically all the work being
down grade, the full cars could be run down by gravity and the empty
ones pushed back by hand. Two men were allotted to each car, and were
able to keep the traffic moving in a manner that would have been perhaps
impossible with any system of mechanical haulage. This system was
apparently justified by the results, for the whole cost of the tunnel
transport, over an average haul of about 2,000 ft., was only about 50
cents per cu. yd., which will be found to compare favorably with
mechanical haulage on similar work elsewhere, provided full allowance is
made for the use of the plant and power.
_Force Employed._--The average force employed on transport, both on the
surface and in the tunnel, is shown in Table 33.
Costs.
During the work, careful records of the actual cost to the contractor of
carrying out this work were kept by the Company's forces; these costs
include all direct charges, such as labor and materials, and all
indirect charges such as head office, plant depreciation, insurance,
etc., but do not include the cost of any financing, of which the Company
had no information.