PHOENIX – Federal security officials said Thursday they will investigate an accident in which authorities said an over-speeding milk tanker collided with seven cars on a Phoenix freeway, killing four people and injuring at least nine.
The wreck occurred late Wednesday after the tanker “did not slow down due to traffic jams,” said the Arizona Department of Public Safety in a statement.
The National Transportation Safety Board said it was sending nine investigators to work with the Arizona Public Safety Bureau to conduct a safety investigation into the crash.
One of the questions NTSB investigators will be investigating is whether the crash could have been prevented if the tanker had been fitted with electronic safety devices, said board spokesman Chris O’Neil. “Automatic emergency braking is definitely something we want to check out,” he said.
Six of the nine injured were taken to hospitals in critical condition, the Phoenix Fire Department said in a statement. The four men and two women were between 22 and 45 years old. Details of the four people killed were not immediately released.
After the first collision, the trailer of the tank truck separated and drove over the center wall of the motorway and landed on the side in the lanes in the opposite direction, said the State Office for Public Security.
The authorities ruled out the possibility of the trucker’s disability, the department said. The trucker has not been identified.
There are currently no federal requirements for articulated trucks to have forward collision warning or automatic emergency braking, although the systems are becoming more common on smaller passenger vehicles.
The systems use cameras and sometimes radar to detect objects in front of a vehicle and they either warn the driver or slow the vehicle down and even stop it if it hits something.
O’Neil said investigators will determine if the tanker had advanced safety equipment and, if so, how it behaved in the crash. If it didn’t have the systems, they’ll see if “collision avoidance technology would have made the severity less or less,” he said.
The NTSB, he said, was investigating several accidents in which large trucks ran into the stopped or slowed traffic. As early as 2015, the NTSB recommended that manufacturers immediately include electronic security systems in the standard equipment. At the time, the agency said the systems could prevent or mitigate more than 80% of rear-end collisions, which cause around 1,700 deaths and half a million injuries annually.
Twenty automakers, representing 99% of US new vehicle sales, signed a voluntary agreement with the government in 2016 to make equipment the standard for all light vehicles by September 1, 2022, and many companies are moving closer to that goal.
O’Neil said the team that drove to the scene of the accident included members experienced in engine mounts, highway design, occupant protection, human performance, vehicle factors, and engineering accident reconstruction.
Investigators will also try to determine if the driver’s distraction was a factor, he said.
“Our investigators will look at the people involved in the accident, the vehicles involved in the accident and the area around the accident,” said O’Neil.
Investigators typically stay on site for five to ten days and publish a preliminary report 30 to 90 days after their fieldwork is complete. Examinations usually take 12 to 24 months.