[BBKing]

Of course if a car lands on the tracks, the track circuit is tripped and the lights go to red anyway (unless you're using the cheaper axle counters which can't tell when a train is or isn't in a section*. Guess what Railtrack used on the West Coast? But I digress). At Great Heck the collision was almost immediate - trains can't slow down and stop in an instant no matter how many idiotic drivers fall asleep and drive onto the tracks or how many signals are put to red in front of the driver - there's a limit to how far you can go to stop the once-in-a-million accident (which wouldn't have killed anyone if there hadn't been a freight coming the other way at that exact moment). Trains are generally tougher than cars, several of which get written off, often with their drivers, every year on level crossings, due to driver stupidity.

*OK, they make a guess at whether there's a train in a section by counting the number of axles that entered it and counting the number that came out. If they match, it assumes there's no train, if they don't, it assumes there is one. Misuse of axle counters caused the 1990 Severn Tunnel crash (the only place in the UK where they were used under BR, as it's too wet to use track circuits).