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 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 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.

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.

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.