What does the safe distance you are required to keep while driving behind another car depend on?
Show the correct answer
Correct answer
A. On the speed with which you're driving.
Explanation
In the photo, we are driving behind a lorry; on the right there is a temporary yellow sign A-30 "other danger" with a plate showing that the left lane is closed and you have to move into the right lane. The safe distance from the vehicle in front of you depends in particular on the speed at which you are driving - answer A.
The Road Traffic Act requires you to keep the distance needed to avoid a collision if the vehicle in front brakes or stops. The faster you drive, the longer the stretch you cover during your reaction time and the longer your braking distance - the latter grows roughly with the square of the speed. That is why it is convenient to measure the following distance in seconds, not in metres: at a higher speed, the same number of seconds means more metres. Engine power (answer B) does not affect how quickly you stop. The width of the roadway (answer C) matters when passing an oncoming vehicle, not for the distance from the vehicle in front. Before the roadway narrows, as in the photo, expect sudden braking and increase your following distance.
Legal basis: Art. 19 para. 1 and para. 2 point 3 of the Road Traffic Act (Prawo o ruchu drogowym)