Dodge County, Wis., engineers needed to quickly and inexpensively replace two bridges built in 1947 and 1950, which were at the end of their useful life. With funding becoming scarcer every year, they turned to the federal government for a solution. And found one! Launched in 2009 with the American Association of State Highway and Transportation Officials, the Federal Highway Administration's (FHWA) Every Day Counts (EDC) initiative is a state-based model for identifying technologies that shorten project delivery, enhance safety, reduce congestion, and improve environmental sustainability. In short, that require fewer taxpayer dollars.
FHWA works with state and local governments and the private sector to identify a set of innovations to champion every other year. One such innovation, championed in 2010 with EDC-3, is the geosynthetic reinforced soil-integrated bridge system (GRS-IBS). Instead of concrete abutments and pilings, alternating layers of compacted fill and geosynthetic reinforcement support the structure. The methodology eliminates the irritating transitional bump by allowing for uniform settlement between the bridge substrucure and the roadway approach. Because construction doesn't require skilled labor and involves equipment common to public agencies, projects can be done in-house in several weeks for 25% to 60% less than traditional replacement methods.
More than 200 bridges in 44 states, Puerto Rico, and the District of Columbia have been built this way. However, only one had been built in Wisconsin. County engineers and contractors quickly overcame their learning curve, though, with the fourth and final abutment taking half as much time to install as the first abutment's seven working days. Their efforts won the project team -- Dodge County as managing agency, Janke General Contractors as primary contractor, OMNNI Associates as design consultant, and raSmith as construction services consultant -- an American Public Works Association 2017 Project of the Year award in the Transportation (less than $5 million) category.
Excavation below subgrade (EBS) was necessary to stabilize the roadway outside of the GRS-IBS section. In extreme cases, EBS was enhanced with WisDOT-approved subgrade reinforcement fabric and 3-inch base aggregate dense backfill to minimize excavation depth and control costs.
Click here for answers to frequently asked questions about GRS-IBS.
