Built from 1912 to 1915 by the Delaware, Lackawanna and Western Railroad Company under President W. H. Truesdale, Chief Engineer G. J. Ray, and contractors Flickwir and Bush, the Tunkhannock Viaduct was 2,375 feet long, 240 feet high, and used 163,000 cubic yards of concrete, 2,500,000 pounds of reinforcing steel, 185,000 barrels of cement, and 48,000 cubic yards of foundation excavation. With the completion of this Nicholson Viaduct, the world's largest concrete bridge, on 6 November 1915, the company finished its Summit Cut-Off, shortening the main line by 3.6 miles, reducing the gradient from 1.23 to 0.68 percent, reducing curvature from 3970 to 1570 degrees, and eliminating 22 grade crossings. In 1976 it was recognized as a National Historic Civil Engineering Landmark.