31st Street Bridge goes out with a blast
Structural steel from the 31st Street Bridge plunges into the back channel of the Allegheny River at Washington's Landing during a controlled explosion Thursday morning. The north end of the bridge will be rebuilt to incorporate a new interchange with Route 28.
A worker puts the cutting torch to structural steel from the 31st Street Bridge after a controlled explosion.
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When it spent $27 million to rehabilitate the 31st Street Bridge in 2006 and 2007, the Pennsylvania Department of Transportation deliberately left the section nearest Route 28 untouched.
The reason for that was underscored with a thunderclap on Thursday. A 195-foot stretch of faded blue, rust-streaked steel collapsed into the Allegheny River back channel, its demise brought about in a conspiracy of gravity and 20 pounds of explosives.
Texas-based Duane Houkom Inc., which from the looks of its website really enjoys a good explosion, wired the doomed bridge section with blasting charges that instantly burned through the steel, causing it to plummet in four convenient pieces.
The explosives "actually cut the metal like a blowtorch would," said Mike Moorman, vice president of construction services for Maguire Group, the construction manager.
About 50 people watched the demolition from a pedestrian bridge that connects the North Shore and Washington's Landing.
They saw the structure explode and fall an instant before the thunderous sound of the blast reached them. They applauded politely.
Within minutes, a barge almost as wide as the back channel, with a crane aboard, was pushed in to pick up the pieces. Mr. Moorman said the job would take 24 to 48 hours.
Traffic was stopped in both directions on Route 28 as a safety precaution and no one was allowed within 1,000 feet of the blast zone.
The bridge section connecting to Route 28 is being removed because the intersection is being reconfigured to allow through motorists to pass without traffic signals. The main line will pass under an intersection that will tie the bridge to on- and off-ramps and Rialto Street.
"You'll have free flow, two lanes, both ways," said PennDOT spokesman Jim Struzzi. "Ultimately it's going to be a dramatic improvement for Pittsburgh infrastructure."
The Route 28 end of the bridge was shut down when the project started in 2010, concluding its 82 years of service. The other end of the bridge was closed in July. Access from the Lawrenceville end is scheduled to resume in December to carry traffic to River Avenue and Washington's Landing.
The Route 28 end of the bridge is expected to open late next year.
First Published August 17, 2012 12:00 am