Accelerated bridge construction
We all know the feeling of frustration when traffic slows to a crawl as you see the telltale signs of traffic cones and reduced lanes up ahead. Large bridge replacement or rehabilitation projects mean that disruptive construction zones can last months into years.
Accelerated bridge construction is a design and construction method that uses prefabricated materials and other strategies to minimize traffic disruptions and reduce onsite construction time. As many components of the bridge as possible are constructed ahead of time so that road closures are required only when moving the elements into place. For projects that do not require custom engineering, movable bridges and accelerated bridge construction can greatly decrease construction disruptions without sacrificing quality. Standardized approaches streamline the activities required to get bridge replacement systems designed and built in less time -sometimes installed in hours or days, rather than weeks or months.
Keep the Work Off the Road – Kittery, Maine
The Kittery Route 1 Overpass bridge was over 70 years old and located in a tourist destination area. Using accelerated bridge construction saved the Maine DOT in construction costs and shaved significant time off the project. The precast concrete elements were delivered on time, and the town of Kittery was pleased with the results. The closure of Route 1 lasted less than a month, and the closure of Route 236 lasted only 11 hours. Overall, it took less than a year between when the project was advertised and final construction was complete.
Slide Into Place – Phoenix, Arizona
In the Gila River Indian Community south of Phoenix, they employed a “bridge slide,” the first of its kind in Arizona, to place the pre-manufactured sections of bridge in position. It was done with minimal traffic disruptions and shrunk the construction period from four months to nine days.
The previous 140-foot bridge was built in 1961 and the location sits over a riverbed, which had been known for water spilling over the bridge decks during flood events. During construction, the old structure remained open to traffic almost the entire time. At the final stage of the project, the old structure was demolished and two girders and bridge decks were slid together to form the new bridge.
Jointless Construction – Defiance, Ohio
The Federal Highway Administration worked with officials in Defiance County, Ohio, on a form of accelerated bridge construction that uses geosynthetic-reinforced soil. Rather than drilling a deep foundation, the reinforced soil method builds up the substructure in a faster, simpler way, described as akin to building a layer cake. For this type of bridge, there is a smooth transition from the roadway to the superstructure, resulting in a jointless bridge system. With this approach, the County’s first project, the Bowman Road Bridge, was built in just six weeks saving about 25 percent compared to their conventional bridge construction. They not only succeeded in building a bridge for less money and time, but the County went on to rebuild 25 additional bridges in this same manner.
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