Forces: Stopping Distances

Forces: Stopping Distances

Stopping Distances

  • Stopping distance is the total distance travelled by a vehicle from the moment the driver notices a hazard to the moment the vehicle comes to a complete stop.
  • It can be divided into two parts: thinking distance and braking distance.

Thinking Distance

  • Thinking distance is the distance a vehicle travels in the time it takes for the driver to react to a hazard and apply the brakes.
  • It is affected by several factors:
    • Reaction Time: A longer reaction time increases thinking distance. Reaction times can be affected by fatigue, distractions, alcohol or drugs, and age.
    • Speed: The faster the vehicle is moving, the greater the thinking distance.

Braking Distance

  • Braking distance is the distance it takes for the vehicle to stop once the brakes have been applied.
  • Braking distance is affected by several factors:
    • Speed: The faster the vehicle is moving, the greater the braking distance.
    • Vehicle Condition: Worn tyres or brakes can increase braking distance.
    • Road Conditions: The braking distance can be increased on wet or icy roads because of reduced friction.
    • Vehicle Mass: Heavier vehicles take longer to stop, increasing braking distance.

Factors Increasing Stopping Distance

  • Increasing speed will have a significant effect on both thinking and braking distance, leading to an overall increase in stopping distance.
  • Road conditions such as icy or wet roads will increase braking distance as the friction between the car’s tyres and the road surface is lower.
  • Vehicle condition including poorly maintained brakes or worn tyres will extend the braking distance.
  • Driver’s impairment due to fatigue, distractions or substances such as alcohol or drugs can significantly increase reaction time, thereby increasing thinking distance.

Effects of Shorter Stopping Distance

  • Shorter stopping distances reduce the chance of a collision but have a greater impact when driving at high speeds.
  • Therefore, it is recommended to adjust your speed based on factors such as visibility, road and vehicle conditions, and to ensure your vehicle is well-maintained to keep stopping distances as short as possible.