Welcome to the Roadscapes Wednesday segment! Each week here on Geek Alabama, Roadscapes Wednesday will feature roads and infrastructure related topics. Geek Alabama Editor / Publisher Nathan Young is often called the “road geek” for a good reason, Nathan loves roads and loves talking about roads!
How do you move a 22-million-pound bridge more than 100 feet without a single crane or wheel?
In Pittsburgh, Pennsylvania, crews are replacing the 75-year-old Commercial Street Bridge, a critical crossing that carries roughly 100,000 vehicles every day. Rather than spending years rebuilding the bridge around live traffic, the project team came up with a much more ambitious plan: build an entirely new bridge alongside the existing one, demolish the old structure, and slide the massive replacement into position during a single 25-day highway closure.
While we couldn’t be onsite for this one, the crews of Mammoet and Fay S&B USA Construction made sure to capture every moment for us.
The new bridge features a unique steel delta-frame design that preserves the appearance of the original arch while allowing the entire structure to be moved into place. To make that happen, heavy-lift specialist Mammoet is using 42 synchronized hydraulic skid shoes to move approximately 22 million pounds of steel 102 feet into its final position.
In this video, you’ll see how the team designed and constructed the new bridge, prepared for the demolition of the original structure, and engineered a massive hydraulic sliding system capable of lifting, pushing, pulling, and precisely positioning one of Pittsburgh’s busiest bridges.
It’s an incredible example of accelerated bridge construction, where years of traffic disruption can be reduced to just a few weeks through innovative engineering, careful planning, and some seriously impressive equipment.
