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    Three Bridges in Three Weekends

    Morrison-Maierle developed a design and replacement strategy using accelerated bridge construction techniques

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    Removing Old Bridges

    First step was to quickly remove the 1930s-era bridges

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    Precast Parts

    54-foot single-span precast concrete structures wait for installation along the closed highway

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    Working Through the Night

    In order to complete the project on time, construction crews worked around the clock for three straight weekends

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    Getting an Early Start

    The team worked with local authorities on a plan to close Deep Creek Canyon in a way that would be of as little impact as possible to area residents and recreationists

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    Setting the Decks

    The projects were completed in two phases that replaced a total of seven bridges

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    A Perfect Fit

    Bridge sections were built off site, delivered to the site, and put into place by the construction team

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    Environmental Work at Night

    In addition to the bridge replacements, stream and floodplain restoration activities were put into place

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    Fast and Furious

    The team determined that traditional construction techniques would have greater impact on streambanks and riparian areas

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    Finishing Touches

    The design also protected areas of severe erosion and worked to revegetate the sensitive streambank areas

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    Finished Project

    This project replaced timber bridges that were constructed in 1930

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    Improved Stream Habitat

    The project enhanced stream habitat characteristics, channel morphology and general stream conditions

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    Better Access

    The bridges improved access in this area that is highly used by recreationists throughout Montana

Deep Creek Canyon Environmental

Awards: 2016 Engineering Excellence Award from the American Council of Engineering Companies of Montana (ACEC), Environmental Category; 2015 Engineering Excellence Award from the American Council of Engineering Companies of Montana, Structural Systems (including bridges) Category; 2014 APWA Rocky Mountain Chapter Project of the Year Award.

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 techniques during weekend closures that came in under budget and did not interrupt the public’s traffic patterns over an extended construction season.

Other project work included cutting back rock slopes to improve sight distance and mitigate rock fall hazards and significant culvert repair and replacement work. All instream and wetland impacts required permitting. Morrison-Maierle’s natural resources staff coordinated closely with the design engineers to identify critical environmental resources and then collaborate in the design to minimize and avoid impacts.