Three Bridges in Three Weekends

High flows during the 2011 spring runoff resulted in significant erosion of the US Highway 12 embankment and damaged bridges crossing Deep Creek. The subsequent flooding required emergency maintenance to prevent structural loss and triggered a project to replace three bridges in the initial phase of a three-phase construction program.

After careful analysis, the Montana Department of Transportation (MDT) contracted with Morrison-Maierle to replace the Deep Creek bridges, located in Deep Creek Canyon between Townsend and White Sulphur Springs, Montana, with new single-span, precast concrete structures between 54 and 70 feet long. The existing timber bridges, which were built in the 1930s, were constructed in a narrow canyon through the Big Belt Mountains where the 24-foot-wide, two-lane highway competes with the creek for space on the canyon floor between steep rocky walls.

With advance planning and sound engineering decisions, Morrison-Maierle and its partners designed a bridge foundation and superstructure system that could be built using accelerated bridge construction (ABC) techniques during weekend closures that came in under budget and did not interrupt the public’s traffic patterns over an extended construction season.