Bridge No. L-5573

The Bridge No. L-5573, also known as the Clinton Falls Bridge and Old Mill Bridge, is a historic Pratt through truss steel bridge that spans the Straight River in Clinton Falls Township, Steele County, Minnesota. The public bridge was placed on the National Register of Historic Places (NRHP) on January 25, 1997.StructureThe Clinton Falls Bridge is a single span, pin-connected steel Pratt through truss structure on concrete and limestone abutments. The overall dimension of the combined substructure and superstructure is 125ft by 22ft.The superstructure is eight panels and includes a floor system made up of 3by treated timbers on 5in steel I-section stringers which are themselves supported by 12in steel I-section floor beams. These beams are fastened to the hip verticals with riveted plates and are riveted directly to the intermediate posts, except for one exception: the first post to the east on the south side is welded to the floor beam with a steel plate set eight inches off center; it is uncertain whether this was a repair or a correction of the design as it was being built. Both top and bottom lateral bracing consists of eye rods stabilized at intersecting points with bolted plates. The top chords, end posts, and intermediate posts are channels with riveted cover plates and lacing bars. The hip verticals are double forged eye rods, while the diagonals are double punched eye bars. The counters are turnbuckles. The lateral and portal struts are double angles to which portal bracing (double angles) is connected with ledger plates. The portal struts and bracing make up a riveted unit which is bolted to the end posts. 2in by 6in wooden guard rails are boted to the bridge with angle sections. A builder's plate is fastened to the top portal struts at each end of the bridge.