PHOENIX – Federal safety officials said Thursday they will investigate a crash in which authorities said a milk tanker going too fast collided with seven passenger vehicles on a Phoenix freeway, killing four people and injuring at least nine.
The wreck occurred late Wednesday after the tanker “failed to slow for traffic congestion," the Arizona Department of Public Safety said in a statement.
The National Transportation Safety Board said it was sending nine investigators to conduct a safety probe into the crash in cooperation with the Arizona public safety department.
Among the issues that NTSB investigators will study is whether the crash could have been prevented if the tanker was equipped with electronic safety devices, board spokesman Chris O’Neil said. “Automatic emergency braking is definitely something we want to take a look at,” he said.
Six of the nine people injured in the crash were taken to hospitals in critical condition, the Phoenix Fire Department said a statement. The four men and two women ranged in age from 22 to 45. Details on the four people killed were not immediately released.
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.