In 1883, the steam powered cast iron swing span was replaced by a steel swing span. That swing span was removed in 1993, and replaced with a lift section. The lift section doubled the width of the navigation channel, making river navigation easier for the larger tows commonly seen in the modern era. The lift section was not new, however. It was formerly in place across the Tennessee River near Florence, Alabama, and used by the Southern Railway. The swing span was removed and the lift span was installed with only a 3 day interruption in rail traffic.
The bridge was part of a Chicago to Kansas City route. Part of the track was built by the Wabash, and part built by the MKT. The Wabash later bought the MKT. The Wabash became part of the Norfolk and Western in 1964, which merged with the Southern Railway in the 1980's, becoming the Norfolk Southern.
The Wabash bridge is interesting in that the rail line enters a tunnel just after landing on the Missouri side of the river. There happens to be a high bluff on the west side of the river. The bluff has a rather sheer face. The solution was a 250 foot long tunnel through the bluff. Also note that the river crossing has a grade level railroad crossing right at the edge of the river. Those tracks carry the BNSF Railroad.
In the photos, you can see that one of the truss sections looks different from the others. That span was hit by a tow that had lost power in the heavy spring current on May 3, 1982, collapsing the truss section into the river. Three barges broke loose from the tow, drifted down river, and narrow missed taking down the Mart Twain Memorial Bridge.