Engineering Wonders of the World
Volume I

___________________________________________________________________________________________________________________________________________________. ■> wwwy’ W»i<& ____„ __ . •f* «*W*t .rr«»'’A,-'-< ■ > i.-sf ’ ««».,/y * .. ft X" ~-j. Kg. 13.—HUGE DOUBLE-DECK CAISSONS AT JUNCTIONS OF HUDSON RIVER TUBES WITH THOSE ALONG THE JERSEY SHORE. These caissons, built of reinforced concrete, are 45 feet wide, 45 feet deep, and 106| feet long, and provide a double-deck system which eliminates dangerous cross-overs between trains running in opposite directions. _3BI driven by shield, being in soft soil, below saturation level. One of these land shields is seen in Fig. 9, after its entry into a junction caisson built of concrete, when its work was ended. The south or Cortlandt Street tube of the lower tunnels reached the junction of its headings in January 1909, the north tube in the spring of the same year. Each tube is a mile long between river banks, and its shield- tunnelled length is 5,900 feet. Gradients of 3 to 4 per cent, in the shore sections lead down to its river level of about 90 feet below mean water. The Hudson tunnels project long ago ceased to be a scheme for main-line railways, although