Pittsburgh bridge demolished ahead of lateral slide replacement

Commercial Street Bridge implosion (Image: Fay, S&B USA Construction)

According to local media, the explosive demolition took place Thursday 16 July after being postponed by a day to allow crews additional time to complete final safety checks.

The demolition forms part of an accelerated bridge construction (ABC) programme being delivered by Fay, S&B USA Construction (Fay), a Pittsburgh-based firm specialising in heavy highway and heavy civil construction in the Mid-Atlantic region.

A specialist blasting contractor carried out the implosion with Fay set to complete the remaining demolition and bridge replacement works.

Rather than rebuilding the bridge in its existing location over several years, a new arched delta frame structure has been constructed on temporary foundations immediately south of the old bridge.

Once demolition, clearance and site preparation are complete, the replacement bridge, which weighs more than 11,000 tonnes (22 million lb), will be moved sideways into its final position.

According to the Pennsylvania Department of Transportation (PennDOT), it will be the largest lateral bridge slide ever performed in the state.

This approach has allowed traffic to remain on the existing bridge throughout most of the construction period, rather than taking four years of long-term lane closures.

Closed since 10 July, the highway, which carries more than 100,000 vehicles each day, is expected to reopen on 3 August.

Once the new bridge has been slid into place and connected to the existing roadway, crews will complete paving, utility connections, barrier installation and final commissioning before reopening one of western Pennsylvania’s busiest transport corridors.