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.
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