Speed limits, safe following distance and stopping
What the exam tests
This domain checks whether you can choose a safe speed and a safe gap, not just recall legal limits. Questions test general limits, the two-second rule, reaction distance and braking distance, and the effect of rain, load and tyres.
Core rules
- Unless a sign lowers them, the general Greek limits are 50 km/h in built-up areas, 90 km/h outside built-up areas and 130 km/h on motorways. Posted limits, temporary signs and local regulations take precedence. A limit is a maximum for good conditions, not a target.
- Keep a minimum two-second gap in dry conditions. In rain, at night or when following a large vehicle, increase it to at least four seconds. The gap should be measured from when the vehicle ahead passes a fixed point to when you pass the same point.
- Total stopping distance is reaction distance plus braking distance. Reaction distance grows linearly with speed; braking distance grows with the square of speed. Wet roads, worn tyres and a loaded car increase braking distance.
- On a dry road with good tyres, approximate total stopping distances are 28 m at 50 km/h, 70 m at 90 km/h and 130 m at 130 km/h. These are planning figures, not guarantees.
Worked example
A driver travelling at 90 km/h sees a hazard and reacts after one second. Reaction distance is about 25 m. On dry asphalt, braking distance is about 45 m, so total stopping distance is about 70 m. At 130 km/h the same calculation gives about 36 m reaction plus 95 m braking, roughly 130 m. The reasoning is that 130 km/h is not “44 percent faster” in stopping terms; braking distance is much greater because speed is squared.
Traps
Do not translate the two-second rule into a fixed number of car lengths, because that changes with speed. Do not assume that ABS shortens braking distance on every surface; it mainly helps steering control. Do not treat a 50 km/h limit as safe in a narrow street with parked cars. Do not ignore the effect of a heavy load or low tyre pressure.