Montana Rail Link Bridge No. 207 Truss Rehabilitation
(Room Sagamore 2)
19 Sep 17
11:30 AM
-
12:00 PM
Tracks:
AREMA Technical Sessions- Structures
Bridge No. 207 is a 727-foot long, five span steel truss bridge across the Clark Fork River near St. Regis, Montana. It was constructed in 1908 and needed rehabilitation to improve its structural condition, capacity and useful life. This project constituted a major rehabilitation for Montana Rail Link (MRL) and was further complicated by tight construction timeframes. Rail line shut down was limited to eight hour windows in which construction could be performed. To accomplish the project goals, MRL and KLJ developed the following rehabilitation scope of work: 1. Conversion from an open deck to a closed deck system (which increased the dead load significantly); 2. Removal and replacement of floor beams, stringers and deck; 3. Truss strengthening including installation of cover plates, supplemental gusset plates and replacement of rivets with high strength bolts; and 4. Bearing replacement. The bridge has a combination of skewed piers and square abutments, which causes the approach truss spans to have one side 24 feet longer than the other. KLJ used the finite element software LARSA 4D for the analysis of this complex structural system. Since MRL completed the rehabilitation with their own forces, MRL and KLJ were able to work closely together to develop removal and replacement details that could be accomplished within the eight-hour windows. The project was completed successfully and the bridge will serve the rail industry in Montana for many years to come.