needle-beams

Updated: May 14, 2025

Then needle-beams and posts were placed under each yoke. The concrete forming the track structure was then enclosed with planking to prevent it from cracking and falling. I-beams were then placed under the needle-beams carrying the structures, and these were carried on posts; they were changed alternately until the excavation had been taken out to a depth of about 16 ft. below the surface.

Benjamin Franklin Cresson - Transactions of the American Society of Civil Engineers, vol. LXVIII, Sept. 1910: The New York Tunnel Extension of the Pennsylvania Railroad: The Terminal Station - West