Dunlap's Creek BridgeEdit profile
Dunlap's Creek Bridge was the first cast iron, metal arch bridge in the United States. It was designed by Richard Delafield and built by the United States Army Corps of Engineers. Constructed from 1836 to 1839 on the National Road in Brownsville, Pennsylvania, it remains in use today. It is listed on the National Register of Historic Places and is a National Historic Civil Engineering Landmark (1978).History
There have been four structures on this site. The first two collapsed in 1808 and 1820. The third, a wood frame structure, needed replacement by 1832.
This bridge is constructed using five parallel tubular ribs, each made of 9 elliptical segments to form the 80 feet (24 m) arch.Image
Plaque commemorating Dunlap's Creek Bridge