Милтон-Мэдисон көпірі: Кентукки мен Индиананы жалғастыратын құрылыс

Continuous truss bridge that connects Milton, Kentucky and Madison, Indiana across the Ohio river

The Milton–Madison Bridge (also known as the Harrison Street Bridge) is a continuous truss bridge that connects Milton, Kentucky and Madison, Indiana. It carries approximately 10,000 cars a day. The old structure was replaced with a completely new continuous truss which was constructed on temporary piers adjacent to the operational span between 2011 and 2012 and slid into place after demolition of the old span using a construction method called "truss sliding." The new crossing opened to vehicle traffic in April 2014, and a pedestrian sidewalk opened that October.

This two lane vehicular bridge is the Ohio River crossing for U. S. Route 421. The bridge has a main span of 600 feet (183 m) and total length of 3184.2 feet (971 m). The original bridge had a deck width of a mere 20 feet (6 m), and above the deck the vertical clearance was 16.8 feet (5 m). The new bridge has a 40 feet (12 m) wide road bed, plus a 5 feet (2 m) cantilevered pedestrian only path. Bicyclists are banned from the sidewalk, but may use the new bridge's 8 feet (2 m) shoulders. The bridge provides the shortest distance between Indianapolis, Indiana, and Lexington, Kentucky.

Built by J. G. White Engineering Corp., construction was started in 1928, and completed in 1929, at the cost of $1,365,101.84. It was opened for traffic on December 20, 1929. Originally a toll bridge, on November 1, 1947, at noon the toll was removed. It had a sufficiency rating of 33 out of a possible 100; its superstructure condition rating was considered "poor". A Milton–Madison bridge study was begun by the Indiana Department of Transportation and Kentucky Transportation Cabinet on August 26, 2008. The study had to take in account the Madison Historic District, which is a National Historic Landmark, and the National Environmental Policy Act. The bridge was removed except for several piers in the waterway, which were rehabilitated and widened to accommodate a new, wider steel truss superstructure. Scour mitigation was also performed on the existing piers. The new bridge also features an ADA compliant pedestrian walkway. Construction for the new bridge began in the fall of 2010, with the old bridge remaining open during work on the piers. Walsh Construction Company planned to close the bridge for only 10 days during construction rather than an anticipated year long closure. The team used an innovative construction method called "truss sliding" to "slide" the 3181 feet (970 m) truss into place along steel rails and plates. Emergency ferry service during the 2012 and 2014 bridge closure periods was provided by Madison, Indiana based, Madison Milton Ferry LLC, in partnership with Anderson Ferry of Hebron, Kentucky. Passenger ferry service was provided by Madison based Rockin Thunder Jet Boat Rides LLC during the bridge closure for the final slide. In 15 days over 4000 passengers and 12 dogs were transported in a 6 passenger Jet Boat between Milton Kentucky and Madison Indiana. The cost of the replacement was $103.7 million.

On March 11, 2014, only four days before the truss slide was scheduled to begin, construction workers were installing a mechanism to facilitate the slide when a steel bearing on the southeast corner of the bridge dislodged, causing the bridge to drop by at least 1 feet (0 m) and injuring one worker. Work was conducted to replace the steel bearing ten days later and the bridge opened to traffic at 7:20 PM on April 17, 2014. The pedestrian path opened on October 30 of that year.