Thursday afternoon's extreme heat caused the pavement of Route 422 to buckle the eastbound lanes near the Oaks exit in Upper Providence and the westbound lanes between the Royersford and Linfield exits in Limerick.
MapQuest traffic reports showed a westbound backup of about 1.5 miles in Limerick and about 2.5 miles approaching the Schuylkill River. The Pottstown Mercury said on its Twitter feed that only the left lane was getting by westbound.
Heat buckling on roadways can appear as a small bump in the road but sometimes can cause a major hazard.
The Delaware Department of Transportation explained heat buckling during last July's heat wave:
The excessive heat causes the pavement to expand, but not all the layers of materials expand at the same rate. Often, roads are constructed with a concrete layer under a hotmix overlay. The concrete pavement has a joint system to accommodate expansion and contraction, but in extreme temperatures, the joint cannot accommodate the expansion and the pavement is pushed upward.