Speed and distance
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.