Structure Investigation Information. Mn/DOT Bridge No. 9340 (Squirt Bridge) I-35W over the Mississippi River at Minneapolis, MN

摘要

The Federal Aid Highway Act of 1968 directed the establishment a national bridge inspection program. Accordingly, the Minnesota Department of Transportation, Metro Division Bridge Inspection Unit conducted an annual inspection of Bridge no. 9340 over the Mississippi River at Minneapolis, MN. The bridge also crosses over several roadways, Minnesota Commercial Railroad tracks, & parking lots. Constructed in 1967, the bridge has 14 spans, with a total length of 1,907 feet. The split deck has three through lanes each direction with acceleration/deceleration lanes and 2 ft. shoulders. The bridge deck widens at the north end to accommodate on & off ramps, and curves slightly at the south end. Spans no. 6 - 8, the main river spans, are Fracture Critical steel deck trusses. They are comprised of welded built-up members and are 988 ft. long. The truss is approximately 60 ft. deep at piers no. 6 & 7. The two main trusses are connected by welded floor beam trusses, which cantilever beyond the truss on both sides and support the 27 inches deep rolled beam roadway stringers. At each end of the main truss spans, the truss supports the adjacent approach spans with a unique crossbeam configuration. The approach span beams frame into a crossbeam, which is supported by rocker bearings on the cantilever truss ends. Spans no. 1 - 5 & 9 - 11, the approach spans, have 48 inches deep, welded plate beams, which transition into 33 inches deep welded & rolled steel beams. Connections are riveted. Spans no. 12 - 14, the far north spans, are cast-in-place concrete voided slabs. Due to several factors, including mist from nearby St. Anthony Falls, the bridge deck frequently ices over and becomes quite treacherous. In 1999, an automated de-icing system was installed on the deck with spray nozzles installed in the deck and railings. The systems controls and storage tanks are located on the north end just off the freeway entrance ramp from East University to South I-35W.