This type of mixer proved very efficient on this work. The largest
number of full batches (0.8 cu. yd.) mixed in one plant per hour was about 35; the largest number per day of 10 hours was about 240; but the apparatus was never worked to its full capacity, the quantity of concrete which it was possible to use being limited by other considerations.
The concrete for the foundations was hauled in steel, V-shaped, dumping cars holding about 1 cu. yd., and the concrete for the bench-walls and arches in Stuebner, 1-yd., bottom-dumping buckets placed on small flat cars, as shown by Fig. 1, [Plate XXIV]. Rock packing was handled in Allison 4-yd. cars and also in the cars shown by [Fig. 5], as well as in the Stuebner buckets, the latter, however, being most generally used. Mules were used for a short time at the Weehawken end to haul the concrete in, but proved entirely inadequate to haul the loaded cars up the 1.3% grade, and locomotives were substituted after the headings were holed through. At the western end the cars were allowed to coast in, and, up to the time the headings were holed through, were hauled back by mules; after that they were pushed out by a locomotive which had gone in ahead of them. As a rule, from 8 to 10 cars of concrete and rock packing were sent in, one after the other, in proper order, a boy riding on each car and stopping it at the proper place; all these cars were pushed out together when empty.
PLATE XXIV.
TRANS. AM. SOC. CIV. ENGRS.
VOL. LXVIII, No. 1154.
LAVIS ON
PENNSYLVANIA R.R. TUNNELS: BERGEN HILL TUNNELS.
Fig. 1. K 131. P.R.R. Tunnels, N. R. Div. Sect. K. (Bergen Hill Tunnels) Weehawken Shaft, North Tunnel. Rear view of conveyor for concrete, showing method of hoisting bucket from car on track in hopper over belt. June 7, 07.
Fig. 2. K 130. P.R.R. Tunnels, N. R. Div. Sect. K. (Bergen Hill Tunnels) Weehawken Shaft, South Tunnel. View showing waterproofing (extreme left) portion of completed sand wall, sand wall forms, traveller and end of conveyor overhead. July 22, 07.