Three construction workers were killed Friday in a four-vehicle collision involving a big rig on Interstate 10 in Blythe. The crash was reported about 5:17 a.m. Friday on eastbound I-10 east of Intake Boulevard, according to the California Highway Patrol. A preliminary investigation determined the big rig was traveling east at an unknown speed when it struck a parked attenuator construction vehicle and an unoccupied Chevrolet Silverado before co…