Mark commented to my post How Black Bridge got its Name, and questioned, “How did the truss Black Bridge compare to the truss bridges that used to be across the Codorus in York?” My short answer was, “They were of a truss type, however those bridges from the 20th Century were of metal construction; as opposed to the timber and iron rod construction in the early Black Bridge(s). Those Codorus bridges in York were also of a different truss design.”
The perfect storm came together for the rest of the story; Cliff Satterthwaite had the artwork and I had previously done some additional research for a new series on the Susquehanna Trail. Therefore this post kicks-off that series a few weeks earlier then planned.
Many in York remember the long-standing truss bridge spanning the Codorus Creek on North George Street. The 1968 artwork of Cliff Satterthwaite depicts a northward looking view of that bridge with the former Western Maryland Railroad track crossing in the foreground.
This majestic truss bridge stood into the 21st Century, although just barely. This bridge was replaced with a four-lane concrete bridge; that opened July 16, 2001. The following westward looking Bing.com Birds-Eye View, of the present bridge, includes an arrow indicating Cliff’s viewpoint for his artwork of the former truss bridge.
Just as Black Bridge was the primary bridge carrying the Northern Central Railway over the Codorus Creek, the North George Street Truss Bridge carried The Susquehanna Trail over the Codorus Creek. In How Black Bridge got its Name, I noted the initial Black Bridge (then called Codorus Bridge) was a timber and iron tie rod Howe Truss type bridge. The North George Street bridge was a Pratt Truss type bridge.
Thomas and Caleb Pratt patented the Pratt Truss in 1844. This truss design was pretty much opposite the 1840 Howe Truss; which has diagonals (in compression) slanting to the center of the bridge and vertical iron ties (in tension). The Pratt Truss has internal diagonals (in tension) slanting away from the center of the bridge and verticals in compression. The present Susquehanna Trail (now Old York Road) Bridge over the Yellow Breeches Creek is a fine example of a Pratt Truss type bridge, as seen in the following photo.
Both the Howe Truss and Pratt Truss bridge types transitioned from a combination of wood and iron construction to all iron construction; although the design of the Pratt Truss lent itself to a smother transition. The further transition to all steel bridge construction heavily favored the Pratt Truss type, which is the reason photos of Howe Truss bridges (of any construction) are rare.
Related posts include:
- Susquehanna Trail through York County; Wrap-Up
- How Black Bridge got its Name
- On the Job at Black Bridge
- Blackbridge Road went under Black Bridge
- 4-Lane Interstate planned through Downtown York?
- Guess the Time Required to Paint an INCREDIBLY Long Bridge
- North Penn Street ‘Drawbridge’ was raised with Muscle Power
- Eagle Nest within 700-feet of Route 30