Under what conditions is it obligatory to operate a “speed retarder” while driving downhill?
- When a “warning sliding” sign is placed on the road.
- When the slope rate of the decent exceeds 6% and the length of the decent is more than one kilometer.
- Correct answer: When the vehicle is equipped with a speed retarder and a sign warning about a dangerous descent is placed on the road.
- If a vehicle is equipped with a speed retarder, it should always be operated, also while driving on plane surfaces.
Why this is the answer
The correct answer in the official bank: When the vehicle is equipped with a speed retarder and a sign warning about a dangerous descent is placed on the road.
You must operate the speed retarder when the vehicle is equipped with one and a sign warning about a dangerous descent has been placed on the road. On a long descent, prolonged use of the service brakes makes them overheat and become less effective. The retarder adds slowing force and helps control speed without overloading the brakes. A sliding warning sign does not create this obligation, and there is no obligation to operate the retarder when driving on level ground.