Expect congestion through the weekend if you're traveling on the Parkway East and Parkway West.

On the Parkway East, the work is on the outbound side only, beginning at the Squirrel Hill Tunnel outbound weekend work zone. A single-lane restriction starts at the Downtown side of the Squirrel Hill Tunnel and extends to the Monroeville interchange at Exit 10B. The outbound "climbing lane" between Edgewood-Swissvale and Forest Hills is closed.

At some points over the weekend, the outbound exit ramp to Route 30/Ardmore Boulevard and the outbound exit ramp to Route 8 at the Wilkinsburg interchange will be closed, but both ramps won't be closed at the same time.

The Parkway East this afternoon was backed to the 10th Street Bridge.

"That's to be expected," said Jim Sruzzi, PennDOT spokesman. "That's why we tried to warn people. They were doing a significant amount of work this weekend."

He recommended motorists "strongly consider another way."

The work is scheduled to continue until 5 a.m. Monday.

Parkway West motorists also face traffic disruptions during the periods in which traffic is reduced to a single lane in both directions near the Route 121/Greentree Road interchange at Exit 4A and when the outbound Parkway West off-ramp to Greentree Road is closed.

The schedule calls for the inbound left lane and the Greentree off-ramp to be closed from 7 tonight to 11:30 a.m. tomorrow and from 5 p.m. tomorrow to 6 a.m. Monday.

The outbound left lane closures, which began at midnight, are in effect until 10 tonight, from midnight tonight to 3 p.m. tomorrow and from 6 p.m. tomorrow to 6 a.m. Monday. However, if tonight's Pirates game runs late, the closure will not take place until two hours after the game ends.

Construction also is taking place on the Crosstown Boulevard/I-579 from the Veterans Memorial Bridge to the Liberty Bridge until 5 a.m. Monday. Traffic will be limited to a single lane southbound. The same restriction on the Crosstown Boulevard will be in effect from 8 p.m. Monday through 5 a.m. Tuesday.