Imagine yourself, you just got off of work and it's about 6pm. You get in your car, turn on the A/C and iPod adapter, and you drive home in commuter traffic for about an hour. Maybe an hour and a half if it's a bad day. The only risk you put yourself in is the possibility of missing your appointment with the personal trainer, or running into someone with a bad case of road rage. You aren't, however, hanging from one limb from a speeding train hoping you don't get pushed into the railroad tracks and filleted by a multi ton train.