How will the demolition of the Commercial Street Bridge on the Parkway East work?

The upcoming closure of the Parkway East for the replacement of the Commercial Street Bridge is less than 48 hours away and PennDOT is detailing how the demolition of the existing bridge is going to take place.

The Parkway East will close Friday night at 9 p.m. between the Edgewood/Swissvale interchange and the Squirrel Hill interchange and is expected to remain closed for 25 days while crews demolish and replace the Commercial Street Bridge.

During those 25 days, PennDOT will slide the new bridge into place, but first, the 75-year-old current bridge has to be removed.

With a major road like the Parkway East closed, time is precious and PennDOT says they won't waste a second.

"Quite honestly, literally, as soon as the roads closed, crews will be mobilizing equipment out onto the bridge and start demolition," said PennDOT Senior Assistant Construction Manager John Myler. 

Myler said that crews will access the existing bridge from both the eastbound and westbound sides and meet in the middle.

"Those folks will be working continuously away from the center of the structure, removing the bridge deck," Myler said, adding that demolition work will be happening around the clock. 

Crews have already worked ahead on the superstructure of the existing span, preparing for the demolition.

"There are thousands of holes drilled into the concrete structure right now," Myler said.

Explosive charges will be inserted into those holes and Myler said fencing will help contain the debris as it's blasted so that it doesn't fly too far or harm the new bridge that's adjacent to the existing one.

The demolition blast is expected to take place in the morning hours sometime next week. 

The foundation for the new bridge, located below the existing bridge, has been covered in layers of protective material and once the blast happens, the priority will be to get the demolished structure off of the foundations, which will then allow the new bridge to be pushed into place.

"Somewhere, probably in the order of within the next ten days of the closure, we'll probably be getting that slide," Myler said.

As for the rest of the remains of the old bridge, it'll likely take weeks to clean up the debris underneath the structure.

The cleanup is expected to take some time and will still be going on well after the new bridge is open and carrying Parkway East traffic