Following distance: understand the two-second reference

Convert seconds to metres

Divide km/h by 3.6 to obtain metres per second. Multiplying by two gives distance travelled in two seconds. The table rounds this calculation; it models neither braking nor individual reaction time. Conversion explains why a visually small gap becomes insufficient at higher speeds.

Use a fixed reference

Choose a visible fixed feature beside the road. When the preceding vehicle passes it, count two seconds before reaching the same feature. Do not use a moving vehicle as the reference. Repeat after a speed change or when another vehicle enters the gap. Keep scanning: counting must not distract observation.

Increase margin for conditions

On a wet road, in fog or with an obstructed view, the minimum gap may not provide sufficient margin. Slow and increase spacing progressively. If someone follows too closely, avoid braking to teach a lesson; retain room ahead and let them pass when possible.

Cruise control and driving aids

An adaptive cruise distance setting does not certify recognition of every situation. Read the handbook and remain able to take control. Roadworks, winding roads and stopped vehicles can require particular attention. Adapt to actual conditions even when the aid gives no warning.

When the general reference is insufficient

Article R412-12 also specifies at least 50 metres outside built-up areas when the vehicles concerned exceed 3.5 tonnes maximum authorised mass or 7 metres length and follow at the same speed, subject to its exceptions. Certain structures may impose a greater distance. This table illustrates the general case without replacing those specific rules.

Reference: Code de la route — R412-12 : distance de sécurité ↗

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Common questions