Engineering Wonders of the World
Volume I

122 ENGINEERING WONDERS OF THE WORLD. piles were sunk side by side in each, case (Fig. 23). The finished Battery tunnels have carried a dense traffic of heavily loaded passenger trains for several years, and have afforded every evidence of perfectly satisfactory strength. Fig. 25.—A VIEW IN ONE TUBE OF THE FINISHED STEINWAY TUNNEL. The part in the foreground was driven by shield, and is iron lined. Beyond is seen a rock section, lined with con- crete to a horse-shoe shape. Fig. 26.—THE REAR OF THE SHIELD, STEINWAY TUNNEL. IN ROCK : EXCAVATION BEING DONE AHEAD OF SHIELD. TRACK FOR DIRT-CARS LAID THROUGH LOWER DOOR OF SHIELD. THE STEINWAY OR BELMONT TUNNELS. (EAST RIVER.) Last of the East River tunnels to be begun were the Steinway (Belmont) tunnels at Forty-second Street. They are two tubes, 15 J feet in diameter inside where driven by shield, and 12| feet wide by 13 feet high in the concrete-lined, rock portions (Fig. 24). Between banks each is about 3,000 feet long. Their greatest depth below water is about 100 feet. Lying between the East River Gas Tunnel and the four Pennsylvania Railroad tubes, they share with these the peculiar difficulties of work through seamy rock and quicksand. Fig. 27—THE LOWER TART OF THE FRONT OF THE SHIELD. STEINWAY TUNNEL. View taken after the shield entered the rock. The shield has been battered very badly by the blasting necessary in rock. The problems and methods were quite like those of the Battery and Pennsylvania East River tubes. One point of special difficulty merits separate mention. It happened that near the New York shore the shields cut through the bottom of a large rock heap (dumped there as waste from some building excavation), so open in formation that the air from the tunnel escaped through