Knowing how much time and distance it takes to apply your brakes to completely stop your vehicle can help avoid errors in judgment that can lead to a collision. Three factors determine the time and distance it takes to stop.

Perception time

Perception time is how long it takes to recognize a situation and understand that you need to stop. This can take about three-quarters of a second. Drivers with less experience often take longer to realize a danger exists. Perception distance is how far a vehicle travels during this time.

Reaction time

Reaction time is how long it takes to respond to a situation by moving your foot from the accelerator pedal to the brake pedal. The average reaction time is 3/4 of a second. Reaction distance is how far a vehicle travels during this time.

Braking time

Braking time is how long it takes a vehicle to stop after the brakes are applied. Braking distance is how far the vehicle travels during this time.

Stopping time and distance calculation
Stopping distance calculation

The chart below illustrates the minimum stopping distance for various speeds.

The stopping distances are averages for stopping on smooth, dry pavement.

Stopping time and distance calculation
Stopping time and distance - different speeds.

Many factors affect your stopping time and distance. These include road and weather conditions. Some factors you can control are:

  • your visual search skills as you scan the roadway ahead
  • your decision-making ability
  • your alertness and level of fatigue
  • your use of alcohol or other drugs
  • your vehicle's speed
  • the condition of your vehicle's brakes and tires

Braking

  • When stopping, begin braking early. If you brake too late, your braking distance may not be sufficient.
  • Release pressure on the accelerator before applying the brake to reduce your speed.
  • To finish braking smoothly, release pressure on the brake pedal slightly and then reapply pressure on the pedal just before you come to a stop.
  • If you must stop quickly, use threshold braking. This is applying the brakes without locking the wheels. This is where braking efficiency is at its maximum while still allowing you to steer your vehicle. If the wheels lock, release your pressure on the brake pedal slightly. Applying the brakes hard enough to lock the wheels will cause a loss of steering control. For vehicles with anti-lock brakes (ABS), see information in Chapter 6 under Emergency braking.
  • The Basics of Driving
  • Stopping time and distance