Mammoet recently conducted its largest bridge slide in the U.S. to move in the new I-376 Commercial Street Bridge in Pittsburgh.
The Pennsylvania Department of Transportation's $95 million project used Accelerated Bridge Construction to reduce traffic impact on the public from almost four years of intermittent lane restrictions to just 17 days of around-the-clock closure. The new steel-arched, delta-frame bridge was built beside the original structure over several months and then slid into position after the old bridge was demolished.
Check out PennDOT's video of the demolition and slide below:
The original concrete Commercial Street Bridge opened in 1951 and was rehabilitated in 1980, 2006 and 2012. A new structure, which will be traveled by over 100,000 vehicles per day on one of city’s main thoroughfares, was needed to carry permit loads.
A driving force behind the final movement of the bridge was a specialized skidding system from Mammoet, which used equipment previously deployed in 2016 to install the safe containment structure at the Chernobyl nuclear power plant in Russia, the site of a catastrophic nuclear accident in 1986.
Once all debris from the controlled demolition of the previous bridge was removed, the new 10,000-ton structure — both the deck and main support structures — was installed. The skidding system was chosen by Mammoet for its low height and high load capacity, which would resist transverse force and minimize stresses on the load.
Powered byAdditionally, a temporary frame was installed between the bridge and skid shoes to protect the structure from twisting forces, made possible again by the skidding system’s low height. The final skidding distance came to 102 feet and was performed in one continuous move over a single day shift. The overall bridge replacement project is expected be completed next summer.
Mammoet also credits the system’s newly revamped controls with giving operators better precision and oversight. Each of the 42 skid shoes could be operated independently and were used for four primary supports runs: two at the bridge piers and one at each abutment.
