Stopping Distance & Braking

Three Distances Together = Stopping Distance

Stopping distance = reaction distance + braking distance.

• Reaction distance = the metres covered between seeing a hazard and pressing the brake (avg. 1 s reaction time)

• Braking distance = the metres needed to come to a stop once the brake is fully applied

• Stopping distance = both added together – the real distance you need to avoid a collision

Rule-of-Thumb Formulas (Dry Road)

• Reaction distance ≈ speed / 10 × 3 – example: 50 km/h → 15 m

• Braking distance ≈ (speed / 10)² – example: 50 km/h → 25 m

• Stopping distance at 50 km/h on dry road ≈ 40 m

• On wet road: double the braking distance. On snow / ice: triple or more.

What Increases Your Stopping Distance

Reaction time grows with fatigue, alcohol, distraction (phone), age and bad visibility. A reaction of 2 s instead of 1 s doubles the reaction distance.

Braking distance grows with speed (squared!), worn tyres, wet or icy roads, heavy load and downhill gradient. Always keep enough following distance (rule: 2 seconds, in poor conditions more).