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Understanding Car Stopping Distances: Calculating, Factors, and Tips

01 July 2023

As a driver, understanding car stopping distances is essential for staying safe on the road.

Stopping distance is the distance your car travels from the moment you perceive a hazard to the moment it comes to a complete stop. In this blog post, we'll explain the factors that affect stopping distance, including reaction time and braking distance, and provide practical tips for maintaining a safe stopping distance.

What is Stopping Distance?

Stopping distance is the distance a vehicle covers from when the driver spots a danger or obstacle on the road to when it comes to a complete stop. It comprises two parts; thinking distance and braking distance. Thinking distance is the distance a car travels after the driver spots a danger, obstacle or an incident, and before they apply the brakes. Braking distance is the distance a car travels after the driver has applied the brakes.

What is Thinking Distance?

Thinking distance is the distance your car travels after you spot a danger or obstacle on the road before you apply the brakes. It varies depending on the individual, but the average distance before a driver realises the danger ahead while travelling at 20 mph is six meters. The thinking distance is affected by various factors, including the driver's reaction time, attentiveness, and visibility. A driver's reaction time is the time it takes for them to recognise danger, decide to apply the brakes and finally, press the brake pedal.

What is Braking Distance?

Braking distance is the distance your car travels after the brakes are applied. Braking distance is dependent on the speed of the car, the weight of the car, and the road surface. Since the average car travels six meters before coming to a complete stop when travelling at 20mph (according to the Highway Code), your stopping distance at 20mph will be 12 meters. The faster a car is travelling, the longer the braking distance.

How to Calculate Stopping Distance?

The average stopping distance of an individual car and driver is calculated by adding thinking and braking distance together. When calculating stopping distance, drivers need to consider the speed at which they are travelling. You can easily calculate the stopping distance of your car by following this formula:

Stopping distance = thinking distance + braking distance

Speed Thinking + braking distance Stopping distance
20mph 6m + 6m 12m (40 feet)
30mph 9m + 14m 23m (75 feet)
40mph 12m + 24m 36m (118 feet)
50mph 15m + 38m 53m (174 feet)
60mph 18m + 55m 73m (240 feet)
70mph 21m + 75m 96m (315 feet)

*Sourced: TheAA

The stopping distance at 20mph is around 3 car lengths. At 50mph it's around 13 car lengths.

Factors Affecting Stopping Distance. There are several factors that can affect stopping distance, including Speed, Road conditions - the weather, Tyre conditions and the braking system. Startin Group have come up with a few ways in which you can Improve Stopping Distance these are:

Make sure you are always maintaining a safe speed, keep a safe distance from other vehicles on the road this ensures that you always should have enough time to break within a safe distance.

Regularly check your tyres, ensuring they're in good condition and inflated to the correct PSI before setting off on your journey. Also, ensure that your vehicle's brake system is regularly maintained.

If you're unsure, you can always pop into your local Startin Group Dealership to have a safety check of your vehicle.

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