In 2013, the American Society of Civil Engineers conducted its latest comprehensive assessment of U.S. infrastructure systems. The results painted a grim picture, with the country earning a D+ grade. Along with the unsatisfactory score, the American Road & Transportation Builders Association reports that nearly 60,000 bridges in the U.S. are classified as structurally deficient.
Both findings indicate that plenty of work must be done. And with so many bridges requiring repair, project owners need a solution that helps them construct long-lasting bridges while maintaining efficient construction schedules and minimizing traffic disruption. Accelerated bridge construction (ABC)—which relies heavily on the use of precast concrete products—can accomplish just that.
Many states across the U.S. have worked on highly successful ABC projects. Outside of Pittsburgh, Penn., a bridge that serves as an important artery for local residents and the trucking industry was classified as structurally deficient. But shutting the bridge down for a typical repair would have meant creating a 22-mile detour for drivers.
To minimize traffic disruption, the bridge was targeted for replacement using ABC. The new, 78-ft-long bridge took only seven days to install and was built entirely of precast concrete substructure elements. Precast products used included pile caps, wingwalls, cheekwalls, backwalls, approach slabs and modular precast units for the bridge deck.
In the Midwest, ABC techniques have also played a vital role in bridge construction and rehabilitation projects. For one particularly busy interchange in Michigan, construction crews used a special slide-in method to reduce overall construction time from more than four months to just four days.
For the project—only the third of its type ever completed in the state—engineers specified precast concrete box beams and MSE wall panels. The 4.5-million-pound bridge took between 6 and 7 hours to slide from the temporary substructure onto the permanent substructure. The success of ABC endeavors in the state resulted in a new perspective on bridge work for Michigan Department of Transportation engineers.
To learn more about these projects and ABC techniques, read the full case study.
