Accelerated Bridge Construction

Engineers Adopt New Methods to Replace Old Bridges

In the last two decades, the PA Turnpike Commission (PTC) has completed dozens of bridge-replacement projects to ensure the safety and integrity of these critical structures. However, in 2017, construction was completed on two unique bridge-replacement projects, on the Mainline at milepost 20.47, and on the Northeastern Extension at milepost A57.66. They were the first bridges on the 552-mile toll-road system to be replaced using a modern technique called Accelerated Bridge Construction, or ABC.

Accelerated Bridge Construction (ABC)

Accelerated Bridge Construction is an engineering innovation that employs groundbreaking planning, design and construction methods and materials in a safe, cost-effective way to reduce the time it takes compared to traditional bridge-replacement techniques. ABC has been shown to improve work-zone safety for construction workers and the traveling public as well as project delivery time for transportation agencies and bridge builders. ABC also helps reduce impacts associated with traditional bridge projects, including onsite construction time and traffic disruptions.

Easing Traffic Impacts

Replacing a bridge while safely maintaining traffic can be a daunting engineering challenge and a headache for motorists. Traditional bridge-replacement techniques usually involve multiple overnight Turnpike closures, single-lane patterns, cattle chutes and other restrictions over two construction seasons. With ABC, impacts occur over a single long weekend instead of nine to 18 months of intermittent impacts.

In the fall of 2017, the PTC implemented its first ABC 55-hour closure on the east-west Mainline, I-76, between the Beaver Valley Exit (#13) and the Cranberry Exit (#28). The second 55-hour closure was completed on the Northeastern Extension (I-476) between the Lehigh Valley Exit (#56) and the Mahoning Valley Exit (#74).