HARMARVILLE — One lane in each direction is open on a major highway connecting Pittsburgh to its north and east suburbs a day after a rock slide closed the road.

The highway was closed after boulders fell onto the road about 3:15 a.m. Tuesday. One was estimated at 40 tons.

PennDOT will not reopen more lanes until crews determine it is safe. That could take several days.

The stretch of highway about 10 miles northeast of Pittsburgh is used by about 45,000 vehicles a day. It is prone to rock slides from a hill that was cut away to make room for the road decades ago.

PennDOT was spending $5.1 million to stabilize the hillside when the latest slide happened.