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Thompson Road/Air Line Railroad Bridge
Thompson Road over abandoned RR right-of-way, Howard Township - Cass County
Property Type bridge
Historic Use TRANSPORTATION/road-related (vehicular)
Current Use TRANSPORTATION/road-related (vehicular)
Style Other
Narrative Description main span number: 5 main span length: 35.0 structure length: 169.0 roadway width: 22.7 structure width: 20.4 The Thomson Road Bridge, which is positioned on a north-south axis, is located in rural farmland. The railroad bed which is crossed by the bridge has been abandoned for many years, and the area beneath the structure is overgrown. The original railings consist of concrete posts with pyramidal tops (mostly deteriorated), each joined by five metal-pipe panels between each post. The deck arches slightly, and the structure is skewed. "1919" is impressed in concrete on the outside of the curbs in the middle span.
Statement of Significance This structure is among the oldest examples of a concrete T-beam bridge in the survey, and only one of this type has more spans. The design is quite different from the standard plans used at the time by Michigan State Highway Department. The plans for this structure were probably developed by the railroad company, which had a switching yard and many associated tracks in the area. The tracks under the bridge were originally operated by the Michigan Central Railroad; later, other companies assumed control over the trackage. The main line of the Michigan Central, which was built in Cass County in 1848, is about one-half mile west of the bridge site. After the Civil War, a new railroad called "Airline" linked Jackson with the Michigan Central line at Niles. Within two years, the Michigan Central controlled the Airline routes. A 1935 county history noted that a cut-off was built to connect the Airline route and the main line of the Michigan Central in Howard Township "some fifteen years ago." That date seems to correspond to the 1919 date of the bridge. The wide right-of-way near the bridge was used as a railroad switchyard known as the "Hump." The Thomson Road Bridge is eligible for the National Register under Criterion C, as an excellent example of a concrete T-beam bridge with very good historical integrity.
Period of Significance 1919
Significant Date(s) 1919
Registry Type(s) 12/22/1999 National Register listed
Site ID# P22233