On Friday, Missouri Governor Jay Nixon vetoed a bill that would have allowed a pilot program to test driver assistive truck platooning technology on state highways.

The Governor brought up concerns regarding driver safety, saying that the May 7th self-driving car crash fatality highlighted the fact that the “technology remains unproven.”

The bill had already made its way through both levels of the state’s legislature before being vetoed. STL today reported that if passed, the bill would have allowed for six years of the platooning technology. Semis that are connected by wireless technology would have been permitted to ignore the current 300 foot following distance state law. Proponents of the bill claim that truck platooning would allow a more effective use of the road and would cut down on emissions.

However, Nixon claims that the self-driving technology is not up to par. He stated,

“The risk associated with automated vehicles are even greater considering the size of long-haul trucks and the catastrophic damage that could occur if the technology fails. Using Missouri as a testing ground for long-haul trucks to deploy this unproven technology is simply not a risk worth taking at this time.”

According to Tesla, the recent car crash was the first known fatality in over 130 million autopilot activated hours.