Frankly, we don't know what's going to happen. ♪ ♪ NARRATOR: "Ultimate Crash Test: Countdown." Right now, on "NOVA." ♪ ♪ NARRATOR: Multi-vehicle pileups can be deadly. (glass and metal ...

The two-part NOVA special ULTIMATE CRASH TEST explores what really happens in a multi-vehicle collision through a first-of-its-kind experiment that recreates the conditions of a highway pileup in a ...