This is the longest bridge in St. Paul at 3,369 feet, but the longest clear span is only 372 feet. Its relatively short clearance of 60 feet above the water forces some river boats to fold their smoke stacks when they pass under the bridge on their way to Lambert's Landing downtown St. Paul.
This bridge narrowly averted disaster in 1975 when one of the large main steel girders developed a crack. Despite being less than 10 years old at the time, the crack was already several inches wide. The problem was noticed when the bridge deck sagged by 7-inches. It is only by luck that the bridge did not collapse. Engineers had to jack the southbound lanes back into position, and large steel plates were bolted onto the cracked girder to fix the problem.
The Lafayette Bridge is built with a design that is called "fracture critical". That means that there are certain parts on the bridge where if one such part fails, the entire bridge might collapse. As a result, MN-DOT has been watching this bridge carefully. It is scheduled to be replaced in 2011, assuming that funding is available.
Note—I often find conflicting numbers for the length of a bridge. As bridges are remodeled, the end points sometimes change. Others might have different methods for measuring a bridge, including how they treat any trestles leading up to the bridge structure. In this case, I have seen length numbers of 3,366 feet (NBI), 3,375 (Mary Costello), and 3,709 (Historical Society), yet the end points of the bridge seem unambiguous and have not been changed over time. The 3,366 appears to be a typo of 3,369, and the 3,709 number mistakenly includes the overpass over I-94. The correct number, according to MN-DOT is 3,369, which they quote as 0.638 miles.
