Monday, October 10, 2011

Michigan's Bridges: 20 Mile Road Overcrossing in Calhoun County

August 2011 (42.483 Degrees, -84.907 Degrees) 20 Mile Road OC
Another continuous four span haunched T-girder overcrossing. I wonder if the whole bridge was cast in one go or they staged the construction so two-way traffic could be moved to each side as falsework was put up and taken down? It would be better to cast a continuous bridge at one time, but vertical clearance below the falsework might have been a problem. The vertical clearance of the completed bridge is under 16 ft and so with falsework they would have had about 13 ft, which isn't too bad if a detour could be provided for tall vehicles.

The Historic Bridge Website shows a photo of the bridge plaque, which says the bridge was built by Holloway Construction and Raff and Dexter Contractors in 1960. However, I couldn't find any information on their construction methods. The website also says that this in one of the few remaining examples of this type of bridge that includes the original open steel railing mounted to concrete posts. Open versus closed railing is a source of never-ending controversy, especially for bridges along the coast, and especially because of the litigious nature of today's society.
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Michigan's Bridges: 20 Mile Road Overcrossing in Calhoun County by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

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