OCEANSIDE, Calif. -- A 400-foot-long big rig hauling a radioactive steam generator was parked for the day alongside a North County thoroughfare Monday, blocking a lane and creating a temporary roadside curiosity for passers-by.

The massive truck pulled over about 3 a.m. on the eastbound side of Oceanside Boulevard, just east of El Camino Real, according to police.

The truck, which is carrying the generator from the San Onofre Nuclear Generating Station to another plant in Utah, was parked in that location because it is only allowed to travel at night and there wasn't enough time to get to the next checkpoint before daybreak, Lt. Leonard Mata said.

The rig, which is being escorted by the California Highway Patrol, is slated to get under way again about 9 p.m., the lieutenant said.