Transactions of the American Society of Civil Engineers, vol. LXVIII, Sept. 1910 / The New York Tunnel Extension of the Pennsylvania Railroad. / The East River Tunnels. Paper No. 1159

by James H. Brace; Francis Mason; S. H. Woodard

FOOTNOTES:

[A] Presented at the meeting of December 15th, 1909.

[B] Transactions, Am. Soc. C. E., Vol. LXIX. p. 1.

[C] Minutes of Proceedings, Inst. C. E., Vol. CXXX, p. 50.

[D] The lead of the shield is the angular divergence of its axis from the axis of the tunnel and, in this tunnel, was measured as the offset in 23 ft. It was called + when the shield was pointed upward from grade, and - when pointed downward.