Bulkheads at the ends of the sections were built of rough planking securely braced to the rock, except that a planed board was laid up against the face of the form to make a straight joint. At the end of each section a V was formed, as shown by [Fig. 1, Plate LI]. At all corners, a "return," or portion of the wall running at right angles, was built, and no section of wall was stopped at a corner.
Filling Forms of Lower Face Walls.—A temporary trestle was erected above the elevation of the bridge seat, and a track, leading from the mixer to the form to be filled, was laid on it. At the commencement of each section a layer of mortar (1 part of cement to 2½ parts of sand) was deposited on the bottom. A 1:3:6 mixture of concrete was used; it was run from the mixer into dump-cars and deposited in the form through chutes, three of which were provided for each 50-ft. section, the average length. The concrete was mixed wet, and was not rammed; the stone was spaded back from the face, and no facing mixture or facing diaphragms were used. Work on each section was continued day and night without any intermission from the time of commencement to the time of completion. At frequent intervals the box drains were washed out thoroughly with a hose, in order to prevent them from clogging up with grout.
Plate LI, Fig. 1.— TW 66, P.N.Y. & L.I.R.R. Terminal Station West. Box drains and tie rods, South side, Sta. 184+80 to 185+14. Sept. 17, 08.
Plate LI, Fig. 2.
Plate LI, Fig. 3.— P 46. P.R.R. Tunnels, N.R. Div. Sect. Gy. West. Disposal trestle just before demolition. View of South side showing chutes. Jan. 21, 09.
Plate LI, Fig. 4.— A 54. P.R.R. Tunnels, N.R. Div. Sect. Gy. West & Oj. View across North River on line of Tunnels, looking from New York to New Jersey. Feb. 9, 07.