Our 150th Mystery Bridge takes us to Mannville, in Somerset County, New Jersey, located west of Edison and even New York City. This bridge came to our attention on bridgehunter.com because of its fancy portal bracings as well as the vertical end posts. Judging by the plaque on the portal bracing, the bridge was built in 1875. Judging by its features and the fact that steel was not as comonly used as it was 15 years later, this bridge was definitely built of either cast or wrought iron. The number of spans, judging by the tunnel view, is between four and six, thus making the length of the entire bridge between 200 and 400 feet long. The structure used to serve a railline connecting the area with Philadelphia and Reading in Pennsylvania. In fact, the bridge was part of the Philadelphia-Reading Railroad consortium, which was established in 1833 and had been in service until 1976. It was one of the oldest railroads in the country.
The bridge was replaced with a two-span Parker through truss though the date is not given, nor is there information in bridgehunter.com. Hence the first question that comes about is when the present-day span was built and this span removed.
It is unknown what type of truss was used for this railroad bridge, though at first hand, it appears to have been a Howe through truss design. Yet at the time of its construction, other truss designs were also used that have Lattice features, such as the Post, Whipple and even Pratt. So looks can be deceiving. So the next question is what type of truss bridge was this crossing.
And lastly, the third question behind this bridge is who built this to begin with and what was the motive behind the portals and end posts, which are not only typical for iron truss bridges during that time, but also one of the most ornamental of the bridges in the area? Although these trusses are rare to find these days, decorative truss bridges show not only the engineer’s signature but also the artwork that was put into the structure, especially when it comes to cast or wrought iron. These were dominant between 1870 and 1895 when steel became the norm for truss bridge construction and with it, sleeker truss designs with letter-shaped portals, such as the common A-frame, as well as W, M, WV, and MA, as well as Howe Lattice.
To to review the questions we need to solve for this research:
- When was the truss bridge replaced by the current structure?
- What type of truss bridge was this crossing?
- Who was behind the design for this railroad crossing?
And with that, best of luck with the research. Feel free to submit your comments here if you find some information on the bridge. Happy Bridgehunting and happy trails! 🙂