The ABCs of Accelerated Bridge Construction

​​Over the course of nearly 20 years, PCL Civil Constructors, Inc.​​ has built 26 projects across the United States utilizing accelerated bridge construction (ABC) methods to reduce the overall project durations. PCL’s methods included the use of precast segmental construction, float-ins, and bridge slides, all of which reduce impacts to local businesses, the environment, and traffic.

The new approach span for the Ben Sawyer Swing
Bridge was constructed on temporary bents and
moved into place during a 10-day period, while the
swing span was floated into position.

Using the accelerated bridge construction technique
of lateral slide, the existing bridge remained open to
traffic during construction.

ABC methods shorten project schedules by weeks, months, and sometimes even years. These methods also improve project safety and quality by constructing bridges during times of low traffic, such as in the middle of the night. Accelerated bridge construction improves on-site safety by reducing the amount of time contractors spend working around traffic or atop elevated platforms.

A Smooth Transition

Situated in Charleston, South Carolina, the Ben Sawyer Swing Bridge Replacement​ is a prime example of the benefits ABC offers to both the client and the public. In keeping with the principles of accelerated bridge construction, PCL Construction ensured the project had minimal impact on the surrounding marshland by constructing all site work from a temporary work trestle. This trestle allowed for the quick positioning of new approach spans, which rolled into place while the project team simultaneously removed existing spans with hydraulic jacks and heavy-duty rollers. At more than 1,000 feet in length, the two-lane bridge connecting Mt. Pleasant to Sullivan’s Island required only a 10-day bridge closure for the full replacement of the bridge’s superstructure and swing span.
“PCL Civil Constructors, Inc. utilized innovative and accelerated bridge construction methods in order to build the moveable span offsite and the approaches on-site without effecting traffic,” said David Glenn Jr., construction and maintenance engineer with the South Carolina Department of Transportation. “I have been involved with several design build projects and the innovation and construction methods used on this project were some of the best I have been involved with.”
Using a construction management procurement method, the state of Vermont chose to utilize accelerated bridge construction to replace its I-91 bridges. With high traffic volume a constant occurrence on US Route 5 and I-91, the replacement of the I-91 north and south bridges over US Route 5 in Hartford, Vermont, had to be swift. To minimize traffic disruptions, the project team will construct significant portions of the new bridge adjacent to the existing structure. Over two weekends, the existing bridges will slide out of the way while the new bridge slides into place using the lateral bridge slide method.

A Method to the Madness

Altering the approach from standard construction practices to accelerated bridge construction methods reduces jobsite worker exposure to fewer potential hazards such as high elevation, jobsite traffic, and heavy machinery. The work instead takes place in factory-like conditions where construction perils are controlled and risks are reduced.  Precast segments improve quality control and are typically prestressed, eliminating water intrusions and extending long-term durability of the structure.

By implementing accelerated bridge construction methods when possible, PCL is continuing its commitment to project safety, extending the structure life cycle and improving the lives of communities in which we live and work.


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