| Section A. | Section B. | |
| Foundations— | Per cu. yd. | Per cu. yd. |
| Labor mixing | $0.97 | $0.94 |
| Labor placing | 0.96 | 0.95 |
| Power | 0.14 | 0.16 |
| ———— | ———— | |
| Total | $2.07 | $2.05 |
| Roof and side walls— | ||
| Labor mixing | $0.79 | $0.91 |
| Labor placing | 0.85 | 0.94 |
| Labor setting forms | 2.01 | 1.20 |
| Labor plastering arches | 0.16 | 0.23 |
| Power | 0.28 | 0.15 |
| ——— | ——— | |
| Total | $4.09 | $3.43 |
Fig. 144.—Traveling Form for Side Walls, New York Subway Tunnels.
TRAVELING FORMS FOR LINING NEW YORK RAPID TRANSIT RY. TUNNELS.—In constructing the tunnels under Park Ave. and under the north end of Central Park for the New York Rapid Transit Ry., traveling centers and side wall forms were used for the concrete lining. The mixing plants were installed in the shafts and consisted generally of gravity mixers charged at the surface and discharging into skip cars running on the tunnel floor.
Fig. 145.—Traveling Form for Roof Arch. New York Subway Tunnels.
The forms used in the Park Ave. tunnel are shown by Figs. 144 and 145; those used in the Central Park tunnel differed only in details. The method of work was slightly different in the two tunnels, but was substantially as follows: Three platforms mounted on wheels were used in each set and two sets were employed. Ahead came a traveler carrying the side wall forms, next came a shorter traveler carrying a derrick, and last came the traveler carrying the roof centers. The arrangement as operated in the Central Park tunnel is shown by Fig. 146. In the Park Ave. tunnel the "bridges" were dispensed with, the skips being hoisted through the open end bays of the derrick car and set directly on the cars on the center traveler.
Fig. 146.—Sketch Plan of Traveling Forms, New York Subway Tunnels.
The traveler carrying the side wall forms was set in position and blocked, the grade and line being given by the track rails, which had been set exactly for that purpose. The side wall forms differed slightly in the two tunnels; those for the Park Ave. tunnel shown by Fig. 144 formed the vertical portion of the wall only so that when the arch forms, Fig. 145, followed a space A B was left which had to be molded by separate sector-like forms. The side wall forms for the Central Park work were constructed as shown by Fig. 147, being curved at the top to merge into the arch centers. In the Park Ave. work the wall studs were adjusted in or out by means of wedges and slotted bolt holes. In the Central Park work the studs A Fig. 145 were hung by ¾-in. bolts from the pieces B spiked to line onto the cross-braces. The bottom was then lined up by means of wedges at D. The side wall studs being lined up, the bottom lagging boards were placed and filled behind by shoveling the concrete into them direct from skip cars on the adjacent tracks on the tunnel floor. In this way the side walls were built up to the tops of the forms.