A collision involving an overturned tractor-trailer caused significant disruptions on westbound I-580 in Pleasanton this morning, urging the California Highway Patrol (CHP) to advise motorists of severe delays. The incident, which occurred just east of Hopyard Rd., was reported shortly after 9 a.m., initially blocking the right and center lanes for several hours, as stated by CBS News. By the early afternoon, traffic was constrained to a single-lane closure as crews worked on the scene.