The northbound side and one southbound lane of the Neville Island Bridge will be closed this weekend.
PennDOT says the closure on I-79 begins at 9 p.m. Friday and ends at 5 a.m. Monday.
Northbound traffic will be detoured at the McKees Rocks/Coraopolis exit beginning at 8 p.m. Friday.
PennDOT is asking drivers to avoid the area if they can.
If that's not possible, assistant district executive Jason Zang says prepare for a longer trip.
"We will have police officers on site to help facilitate traffic moving through the detour, but the last time we did it, we had travel times of anywhere between 20 minutes and about 28 minutes," he said.
Drivers trying to go north or east should take I-279. Those heading west should take the Parkway West.
The closure is part of an ongoing project on the bridge that is scheduled through the summer of 2023.
Zang says this weekend, crews will complete some of the project's most critical steps.
"We're actually going to be disassembling some of the primary steel members, so we're going to have jacking towers in place and we're going to be shifting loads," he said. "We can't do that with traffic on the bridge. We're also going to be painting."
This is one of four weekend northbound closures on the bridge in 2021.
