and the last eight or ten sections built had to be rubbed down with a wooden float in order to obtain a suitable finish.
In designing the forms for all exposed surfaces in the tunnels, it was the desire of the contractors to obtain directly from them a surface which would be satisfactory to the engineers without further finishing than the patching of minor defects. In this they were generally quite successful, and excellent results were obtained, as shown in the view of the finished tunnel, Fig. 2, [Plate XXVII]. The surface of the bench-walls was obtained solely by spading the face with a flat spade as the work progressed. No after treatment was resorted to, except for the few sections where the forms became worn. The top of the bench-wall was finished with a float about 2 or 3 hours after the concrete was placed.
When the work was well organized, a bench-wall was built at each end each day, one day in the North Tunnel, and the following day in the South. During the time sand-walls were being built, a sand-wall and bench-wall were built on alternate days in each tunnel, care being taken that when a bench-wall was being built in one tunnel, the sand-wall was being built in the other, this being necessary in order to equalize the work of the night gang and the conduit layers as well as the transportation.
The conduit layers on the day shift, two or three men and a foreman, required about 2 hours in the forenoon and 1 hour in the afternoon to lay their portion of the conduits, and usually finished this work by 3 P.M. At other times during the shift they were utilized at those points where rock packing was heaviest, and when the packing was brought in in the large cars, as shown in Fig. 1, [Plate XXVI], these men helped unload it so that the track could be cleared as soon as possible. When water-proofing was to be done, the number of men in this gang was increased, so as to enable them to do that work also.
PLATE XXVI.
TRANS. AM. SOC. CIV. ENGRS.
VOL. LXVIII, No. 1154.
LAVIS ON
PENNSYLVANIA R.R. TUNNELS: BERGEN HILL TUNNELS.
Fig. 1. K 167. P.R.R. Tunnels, N. R. Div. Sect. K. (Bergen Hill Tunnels.) View of form for circuit breaker chamber at Sta. 286, and travelling gantry for placing concrete in arches, looking Easterly from near Sta. 280+85, South Tunnel. Oct. 3, 08.
