Walia

I. BACKGROUND

At 1:20 a.m. on May 25, 2018, a tractor trailer overturned on eastbound Interstate 80 (I-80 east). It caught on fire and spilled fuel and wreckage across the highway, blocking all four eastbound lanes. The accident occurred west of the Carquinez bridge and Pomona exit and east of the Cummings Skyway exit. The California Highway Patrol (CHP) responded, and the accident site was marked with cones and flares and flashing lights from emergency responders. A CHP officer in charge of the accident site concluded it would take hours to clear. Just before 2:00 a.m., he directed Caltrans to close I-80 east at Cummings Skyway and divert all eastbound traffic off the highway at that exit. A Caltrans maintenance supervisor received the directive minutes later and promptly went to the accident site but did not effect a closure. Plaintiffs assert Caltrans took no steps in the next two hours to close I-80 east or divert traffic. Caltrans concedes there is a factual dispute whether it did so. For purposes of this appeal, we will assume it did not. Caltrans undisputedly did not post other warnings to approaching drivers of the freeway blockage at the accident site or of traffic…