A section of Route 22/322 in Perry County has been shut down so workers can remove loose rock from a cliff face.
The westbound lanes west of Newport were closed Monday morning and will remain closed for up to two weeks while the unstable rock is removed.
A PennDOT spokesman said a recent inspection found several large sandstone blocks with weakened support. There is concern that rocks or portions of the slope may fall onto the highway.
A detour follows Route 34 southbound, West Shortcut Road and West Juniata Parkway.
Larger vehicles and through traffic should use Route 11/15 north to Liverpool, Route 17 west to Millerstown, and North Market Street back to Route 22/322 to avoid the closure.