I saw a "must get past the steam-roller" once. Went to Brighton to see the end of the "Historic Commercial Vehicles" run from London to Brighton a few years ago. The finishing line was a sort of one-vehicle-wide triumphal arch on the esplanade. A steam roller (a real one, with a boiler and coal and steam) was hurtling at about 3 MPH towards the arch.
Just a few 10's of yards short, some twat in a car decides to overtake the steam roller and cut in through the arch. Unfortunately, he'd left it a bit late, and cut the approach angle too steeply. He tried to reverse, and stalled. So there he was, stuck in front of a charging steam-roller.
The guy driving the steam roller did an emergency stop. Have you ever seen 25 tons of steam roller doing an emergency stop? Shove the reversing lever into neutral, wind the throttle shut, then screw down the brakes.
He managed to stop a few inches from the car, which, I think, was a real shame.