Stopping Distances

• Stopping Distance


  The sum of thinking distance and braking distance
• Emergency stop


  1. Maximum force applied by brakes

  2. Shortest possible distance
• Thinking distance


  The distance the car travels during the driver's reaction time (the time between the driver seeing a hazard and applying the brakes)
• Braking distance


  The distance taken to stop under the braking force (once the brakes are applied)
• Typical car braking distances are 14 m at 30 mph, 55 m at 60 mph and 75 m at 70 mph
• Your speed


  The faster you're going, the further you'll travel during the time you take to react
• Your reaction time


  The longer your reaction time, the longer your thinking distance
• Factors affecting reaction time

  • Tiredness
  • Drugs or alcohol
  • Distractions
• Your speed


  For a given braking force, the faster a vehicle travels, the longer it takes to stop
• Weather or road surface

  If it is wet or icy, or there are leaves or oil on the road, there is less grip (and so less friction) between a vehicle's tyres and the road, which can cause tyres to skid
• Tyre condition


  If the tyres of a vehicle are bald (they don't have any tread left) then they cannot get rid of water in wet conditions, leading to skidding
• Brake condition


  If brakes are worn or faulty, they won't be able to apply as much force as well-maintained brakes, which could be dangerous when you need to brake hard
• You need to be able to describe the factors affecting stopping distance and how this affects safety-especially in an emergency
• Icy conditions increase the chance of skidding (and so increase the stopping distance) so driving too close to other cars in icy conditions is unsafe
• The longer your stopping distance, the more space you need to leave in front in order to stop safely
• Speed limits are really important because speed affects the stopping distance so much