Speed and distance

Speed vs stopping distance, spacing rules and adapting to conditions.

Stopping distance grows rapidly with speed. Keep margins that fit sight, surface and traffic.

3‑second rule

  • Dry: ≥ 3 seconds behind the vehicle ahead
  • Wet/dark: 4–5 seconds
  • Snow/ice: 6+ seconds

Stopping distance formula

Total = reaction distance + braking distance. Reaction distance ≈ 0.8 × speed(km/h). Braking distance grows with speed² and depends on grip.

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