The defensive driver needs to keep a safe interval between his vehicle and the vehicle ahead. The “timed interval” theory, can help the driver make a more accurate judgment of what that means at different speeds, in fair weather and foul.
The timed interval
The “timed interval” can be used at any speed. It is based on the distance a vehicle will travel in a given period of time. A three second interval should allow an adequate stopping distance for passenger cars and two-axle trucks with normal driving conditions. The “timed interval” should be increased to four seconds or more for larger axle combinations. Add an extra second of following distance for any unsafe conditions as you drive (poor road conditions, low light, bad weather, blocked visibility ahead due to a large vehicle, etc.). Because conditions may vary so much, these timed intervals should only be used to indicate one thing, “that you are following too close.”
The countdown plan operates this way:
- Focus on the vehicle ahead as it reaches a fixed object such as a tree or traffic marker alongside the road.
- At that moment, begin counting at a medium pace — “1,000 and 1, 1,000 and 2, etc., 1,000 and 3” until your vehicle reaches the fixed object. Each count will be about a second.
If your vehicle passes the object before the end of the suggested following distance time interval count, you’re following too closely!
171-1030 (02/14) LC 11-389