Why A Train Ran 66 Miles Completely Out Of Control

A runaway freight train covering 66 miles without a crew, without functioning brakes, and without anyone able to stop it represents the railroad industry's most feared operational failure — and it has happened more than once on American mainlines. The physics of a loaded freight train on a descending grade with failed air brakes produce acceleration that conventional friction braking cannot overcome once a critical speed threshold is crossed. The CSX runaway in Ohio in 2001 — the incident that inspired the film Unstoppable — ran 66 miles before being stopped through a combination of emergency derailing switches, locomotive attachment attempts, and the controlled application of a pursuing locomotive's dynamic braking against the runaway's rear coupler.