The Tennessee Department of Transportation Sunday morning conducted quarterly testing on the Market Street Bridge in downtown Chattanooga. The bascule bridge spans the Tennessee River between downtown Chattanooga and the Northshore District. At the time of its completion in 1917, the 300-foot main span was the longest rolling-lift bascule span in the world. The bridge is listed on the National Register of Historic Places. Four times per year, TDOT closes the bridge to test its hinge mechanism, as mandated by the US Coast Guard. (Photo by David Laprad. Some information from TDOT.)