SILVERTHORNE, Colo. — Colorado transportation officials say a second test of using pace cars to reduce congestion on Interstate 70 in the mountains has gone smoothly.

Transportation officials say preliminary results show that when traffic slows down, vehicles are able to pass through the tunnel without creating gridlock.

According to KUSA-TV, Silverthorne police and Colorado State Patrol vehicles served as pace cars on Sunday, driving 45 to 55 mph in the center or left lane with their emergency lights.

Another test is planned for this winter.