Among the bills vetoed by Gov. Jay Nixon on Friday is a measure to create a pilot program allowing tractor-trailers to use "connected vehicle" technology.
Truck drivers taking part in the testing would have been exempt from a state law barring them from following other trucks within 300 feet. The Missouri Department of Transportation and state highway commission were to spearhead the project.
The program also would have tested "truck platooning," a wireless connection between commercial trucks. Benefits of platooning include better fuel economy and safety, MoDOT has said.