A professional driver is operating a loaded freight vehicle along an asphalt highway where the posted dry-weather speed limit is . A steady rainfall begins, causing the pavement surface to become thoroughly wet throughout the route. According to official commercial driver safety guidelines for wet road conditions, what speed adjustment should the driver make, and how should the vehicle's auxiliary retarder be managed?
- ALower vehicle speed to and switch the auxiliary retarder to high mode to preserve foundation brakes.
- Lower vehicle speed to and turn off the auxiliary retarder system.Answer
- CKeep driving at through straight stretches and execute heavy service braking after entering upcoming curves.
- DTrim speed by only to , assuming that wet pavement does not affect overall perception, reaction, and stopping margins.
Answer
Lower vehicle speed to and turn off the auxiliary retarder system.
On wet pavement, commercial motor vehicles must reduce speed by approximately one-third (from down to roughly ) to maintain adequate stopping space and prevent hydroplaning. Furthermore, auxiliary retarders (engine, exhaust, or driveline) must be turned off whenever road surfaces are wet or slippery, because their braking force applies exclusively to drive axles and can cause a sudden drive-wheel skid or jackknife.
Step-by-Step Solution
Key Concept
Commercial vehicle speed reduction rules for wet roads and auxiliary retarder deactivation on slippery surfaces.
Estimated Time:1m 0s