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glatt · 11-09-2011, 10:09 AM

The 3 second rule is a good one. It should keep you from ever rear ending the car in front of you, at any speed. That's because even if the car in front of you panic brakes to a dead stop, you still have 3 seconds to also panic brake and not hit them.

But if the car in front of you hits a deep pothole or debris in the road, you have even less time to stop before you hit that debris. That's because you can't count on the distance the car would continue traveling as it slowed down and stopped. That pothole isn't moving.

You're going 60MPH, that's 88fps. You see the car in front of you hit a deep pothole and get taken out. You might be able to swerve to avoid it, but if you can't, that pothole is three seconds, or 264 feet away. It takes you 1 second (typical driver reaction time) to hit the brakes. That's if you are paying attention. You're now 176 feet away from the pothole as you start braking. Typical stopping distance is about 130 feet, unless you have a sweet sports car. So you've got a 46 foot buffer. If you are tuning the radio, and let a second go by before you notice the car in front of you hit that pothole, you're hosed.

11-09-2011, 10:09 AM	#10
glatt ™ Join Date: Jul 2003 Location: Arlington, VA Posts: 27,717	The 3 second rule is a good one. It should keep you from ever rear ending the car in front of you, at any speed. That's because even if the car in front of you panic brakes to a dead stop, you still have 3 seconds to also panic brake and not hit them. But if the car in front of you hits a deep pothole or debris in the road, you have even less time to stop before you hit that debris. That's because you can't count on the distance the car would continue traveling as it slowed down and stopped. That pothole isn't moving. You're going 60MPH, that's 88fps. You see the car in front of you hit a deep pothole and get taken out. You might be able to swerve to avoid it, but if you can't, that pothole is three seconds, or 264 feet away. It takes you 1 second (typical driver reaction time) to hit the brakes. That's if you are paying attention. You're now 176 feet away from the pothole as you start braking. Typical stopping distance is about 130 feet, unless you have a sweet sports car. So you've got a 46 foot buffer. If you are tuning the radio, and let a second go by before you notice the car in front of you hit that pothole, you're hosed.