You are travelling at 30 km/h. According to the rule of thumb, the braking distance is 9 metres when braking normally. How long is the braking distance under the same conditions when travelling at 60 km/h?

Your answer is correct. In Germany, the braking distance increases with the square of the speed. The rule of thumb is: braking distance (in meters) = (speed in tens) × (speed in tens).

For 30 km/h: 3 × 3 = 9 meters.
For 60 km/h: 6 × 6 = 36 meters.

So if your speed doubles from 30 km/h to 60 km/h, the braking distance becomes four times as long, jumping from 9 meters to 36 meters. This demonstrates why higher speeds greatly increase stopping distances and why it’s important to adjust your speed to traffic and road conditions.