A major USA bridge replacement project that uses accelerated bridge construction (ABC) principles is starting.

Construction Engineer Cowi is about to install steel piles for the temporary sliding towers that will ultimately move into position the new Commercial Street Bridge in Pittsburgh, Pennsylvania in the north east of the USA.

The new arched delta frame bridge will be built south of the present bridge, which will be removed. Construction teams will slide the new structure into place laterally in the middle of 2026. The project uses ABC techniques to minimise disruption of a heavily travelled route.

Commercial Street Bridge takes the I-376 Parkway over a valley containing a public open space and walking trail. The structure is suffering from spalled concrete and cracking. The condition of the deck, floor system and arch spandrel columns prevent the structure from carrying large or oversize vehicles. It was rehabilitated in 1980 and 2007, and strengthened in 2012.

PennDOT and the US Federal Highway Administration are working together on the US$95 million project, with HDR as consultant. Work will also include new overhead signage, a new eastbound retaining wall, changes to an off-ramp to increase vertical clearance, concrete median barrier replacement, sanitary sewer line relocation, upgrades to guide rail, improvements to the traffic management systems and CCTV, as well as site restoration for Frick Park and the walking trail.

In January 2022, Pittsburgh experienced the collapse of the Fern Hollow Bridge, which crosses another city park. The National Transportation Safety Board partly attributed this incident to failings in the city’s bridge maintenance processes (link opens in new tab).