A burning tractor-trailer on northbound Highway 99 at Avenue 7 tied up traffic Tuesday morning north of the Fresno-Madera county line.
The incident, which began shortly after 7 a.m., snarled northbound traffic for more than four hours.
No injuries were reported.
The California Highway Patrol kept the left lane open through most of the incident, but a diesel spill forced emergency workers to call in a Madera County Fire Department hazardous materials unit, further complicating the situation.
The CHP reported the right lane was opened shortly before 11:30 a.m.
It was the fourth big-rig incident on Highway 99 in recent weeks, which has renewed concerns about the highway’s safety. Two weeks ago there was a fiery gas truck crash near Atwater. Then there was a truck crash at the interchange of Highways 99 and 152, and a hay truck crash.