Thomson Rd. / Abandoned Railroad

County: Cass

City/Township: Howard Twp.

Location: Thomson Rd. / Abandoned Railroad

Year Built: 1919

About this Bridge:
The Thompson Road Bridge is eligible for the National Register as an excellent example of an early concrete T-beam bridge with very good historical integrity. This grade separation is among the oldest examples of a concrete T-beam highway bridge in the state.

The design is quite different from the standard T-beam plan which the Michigan State Highway Department had developed in the 1913-1914 biennium, but used sparingly during that decade. The plans for the Thompson Road Bridge 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 the "Air Line" linked Jackson with the Michigan Central line at Niles. Within two years, the Michigan Central controlled the Air Line routes. A 1935 county history notes that a cut-off was built to connect the Air Line 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."