1. Smash semis together. Park the first few across the road. Then have crews jump as bricks on the accelerator produce some truly impressive collision art. Yes big boy tow trucks and cutting torches could clear the mess in a few hours. Make sure the trucks have lots of gasoline on board in breakable containers. Putting out big fires is the first laborious effort.
2. Large gasoline containers at the highest point of the road with timers to release gasoline in a steady stream with remote control ignitors to light them up. I think few truck drivers would want to drive through a curtain of flame. I am not sure about tanks.