Rain may have been a factor in the latest jumble early Tuesday in the Newhall Pass tunnel, 25 miles north of downtown Los Angeles, investigators said.
An investigation by The Associated Press found that more than a decade before the deadly pileup five years ago, authorities warned that the stretch of freeway was dangerous and steps should be taken to improve safety.
Highway officials cut grooves into the pavement to improve traction, but a state police request to routinely close the road in stormy weather was rejected, the AP found.
The state later raised the speed limit in the tunnel from 45 mph to 55 mph.
Tuesday's crashes started when a big-rig spun out and jackknifed after traveling through the southbound tunnel just after 2 a.m. Three big-rigs traveling behind slammed into the wreckage, CHP Officer Mike Harris said.
Three other big-rigs managed to slow down and stop. But Harris said five other trucks, including a dump truck, collided in a second chain-reaction crash in the tunnel that has two lanes heading the same direction.
The driver of one truck was pinned, and it took firefighters more than three hours to get him out. He was hospitalized with injuries that Harris described as non-life threatening.
There was a minor diesel fuel spill and no fire.
The wreckage was expected to be cleared and the bypass reopened by 2 p.m. Tuesday.
In the October 2007 crash, a truck driver speeding on the rain-slicked interstate crashed into a median barrier, setting off chain-reaction collisions that turned the tunnel into an inferno and left three dead. More than two dozen vehicles were involved.
The collisions closed the busy highway for two days and cost $17 million to clean up and repair.
Faulty brakes on the first truck and stormy weather contributed to the collision, but CHP investigators said excessive speed was the primary cause.