After the initial collisions, the trailer of the tanker rig separated and went over the freeway's median wall and ended up on its side in the lanes going in the opposite direction, the state public safety department said.
Authorities ruled out the possibility that the trucker was impaired, the department said. The trucker was not identified.
At present, there are no federal requirements that semis have forward collision warning or automatic emergency braking, even though the systems are becoming common on smaller passenger vehicles.
The systems use cameras and sometimes radar to see objects in front of a vehicle, and they either warn the driver or slow and even stop the vehicle if it’s about to hit something.
O'Neil said investigators will determine if the tanker had any advanced safety equipment and if so, how it performed in the crash. If it didn't have the systems, they will determine if “collision avoidance technology would have mitigated the severity or prevented it altogether,” he said.
The NTSB, he said, has investigated several crashes involving big trucks hitting stopped or slowed traffic. As early as 2015, the NTSB recommended that manufacturers should immediately include electronic safety systems as standard equipment. At the time, the agency said the systems could prevent or mitigate more than 80% of the rear-end collisions that cause about 1,700 deaths and a half-million injuries annually.
Twenty automakers representing 99% of U.S. new passenger vehicle sales signed a voluntary agreement with the government in 2016 to make the feature standard on all light vehicles by Sept. 1, 2022, and many companies are progressing toward that goal.
O’Neil said the team heading to the crash scene included members with experience in motor carriers, highway design, occupant protection, human performance, vehicle factors and technical crash reconstruction.
Investigators also will try to determine if driver distraction played a role, he said.
“Our investigators will look at the people involved in the crash, the vehicles involved in the crash and the environment in which the crash happened,” O’Neil said.
Investigators generally stay on the scene for five to 10 days, and they publish a preliminary report 30 to 90 days after finishing their field work. Investigations usually take 12 to 24 months to complete.
Krisher reported from Detroit.