According to Sina Finance, the U.S. Department of Transportation said Wednesday evening that it has approved five-year exemptions for Aurora and other autonomous truck companies, allowing them to avoid a rule requiring drivers to place warning devices around stopped trucks.

The department said it agreed to let autonomous truck companies use warning lights mounted on the truck cab instead of requiring a human driver, and said the lights provide an equal or higher level of safety. Aurora said it currently has about 20 autonomous trucks operating on the road and that the decision reflects government recognition of the economic and social benefits of autonomous trucks. Companies using the exemption must notify the Federal Motor Carrier Safety Administration in advance and disclose any crashes that occur when the cab-top warning lights are activated or should have been activated. The agency said it will revoke the exemption if safety falls below the level maintained before approval.