A bridge resurfacing project threatens to tie up the westbound Schuylkill Expressway (I-76) in South Philadelphia for much of the weekend.

From 8 p.m. Friday until at least Sunday morning - and possibly until 5 a.m. Monday - only one lane will be open at the University Avenue/Grays Ferry Avenue Interchange (Exit 346B), according to PennDOT.

Motorists are urged to find alternate routes.

For example, drivers crossing the Walt Whitman Bridge from New Jersey could take I-95 North to I-676 West (the Vine Street Expressway) to meet up with the Schuylkill in Center City.

Taking I-95 South to the Blue Route (I-476 North) is another way to bypass the construction on the way to the western suburbs.

The project involves putting new concrete on two bridges that support the expressway over two streets, railroad tracks and the river.

The second lane should reopen "Sunday morning or early Sunday afternoon," PennDOT said.

The contractor, however, could continue work until 5 a.m. Monday if needed.

The weather forecast look favorable: mostly clear skies on Saturday.

Expect another half-dozen weekend lane closures from late August into October along the same stretch - three westbound, three eastbound.

The expressway carries about 130,000 vehicles a day past the University Avenue/Grays Ferry Avenue Interchange, according to PennDOT.

Live traffic cams: To view live video feeds of highways in the Philadelphia area, including I-76, go to www.dot.state.pa.us/penndot/districts/district6.nsf/cam_map2?Openpage.

Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.