HARRISBURG, Pa. — The Pennsylvania Turnpike is replacing two bridges using a construction method that will close sections of the heavily traveled interstate for a single weekend in each instance.

The agency said Thursday it will replace a bridge on the Interstate 76 main stem near Rochester in Beaver County the weekend that starts Friday, Sept. 22.

That will be followed the weekend of Sept. 29 with a new bridge outside Allentown on Interstate 476, the Northeastern Extension.

Detours will be in place in both directions for 55 hours, giving crews time to tear down the existing bridges and position the new spans.

The bridge over Brush Creek in Beaver County is nearly 66 years old. The bridge over Crackersport Road outside Allentown opened in 1957.