There have been 4 traffic bridges over the Illinois River in Seneca, Illinois since the town’s incorporation in 1865.
The first bridge was built in 1866. Unfortunately, this collapsed and had to be replaced. The replacement (2nd bridge ) was an iron one. It was built in 1877 and stood in place until 1932.
The third bridge was a 14 panel rivet–connected Pennsylvania through truss, fixed type. Its length was 1,510 feet. The longest span is 364 feet. There were two lanes. The bridge width was 23 feet. Its height above water was 48 feet. The builder/contractor was Wisconsin Bridge and Iron Company of Milwaukee, Wisconsin. It was rehabbed in 1986. It was demolished in 2010.
The current bridge is a two lane one. It is a steel girder type with concrete decks. The width is 40 feet. Each lane is 12 feet. There are two shoulders and a single walkway. Main span is 350 to 375 feet.
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