PITTSBURGH -- Motorists using the Parkway North should be prepared for a major detour near the Perrysville exit.

All southbound traffic is being rerouted onto the HOV lanes at the Perrysville exit.

The Pennsylvania Department of Transportation is closing the southbound lanes so workers can repair bridges over the interstate.

During the work, the Perrysville on-ramp and the Venture Street off-ramp will be closed.

Drivers detoured onto the HOV lanes must stay there for two miles. They can get off just south of the Venture Street exit. Fifty-thousand vehicles use the lanes weekly, PennDOT said.

Concrete barriers are being removed so drivers can get back on the interstate. PennDOT originally planned to close only half of the interstate. But officials said closing the entire roadway will allow workers to finish the project several weeks sooner.

The project is expected to last about six weeks. The northbound lanes will not be affected.