Flathead River Bridge
Project consists of reconstruction of an existing 4 span bridge structure with a new 3 span bridge structure crossing the Flathead River just west of Bigfork, Montana. The project is located within a highly active seismic area. Poor subsurface soil conditions and high anticipated seismic forces presented many unique design challenges throughout the project corridor. Site Specific Response analysis was performed by our staff to develop seismic design specra for the project to address liquefaction potential, lateral spread, and seismic induced settlement, and other design criteria. The depth of the Flathead River also made conventional construction very difficult. Support of the structure required a unique cost effective solution that will stand the test of time.