A commercial motor vehicle is traveling on a highway posted at when a sudden downpour leaves standing water across traffic lanes. According to standard commercial driving rules for speed and road conditions, how should the driver manage vehicle speed and control systems?
- AReduce vehicle speed to approximately while setting the engine retarder to maximum resistance to maintain drive-wheel traction.
- Reduce vehicle speed by about one-third to approximately , ensure the engine retarder is turned off, and ease off the accelerator if steering control feels light.Answer
- CMaintain the posted cruising speed on straight sections and apply hard service brakes only after entering curves or standing water.
- DReduce speed slightly by under the assumption that vehicle braking distance alone determines total stopping distance regardless of surface moisture.
Answer
The driver should reduce speed by about one-third to approximately , ensure the engine retarder is turned off, and ease off the accelerator if steering control feels light.
Standard CDL safety guidelines require reducing speed by about one-third on wet roads (from down to approximately ). In addition, engine retarders must always be disabled on wet, icy, or snow-covered surfaces because the supplemental drag on drive axles can easily break wheel traction and produce a skid. If hydroplaning begins, the driver should release the accelerator smoothly rather than braking hard.
Step-by-Step Solution
Key Concept
On wet roads, speed must be reduced by about one-third, engine retarders must be disabled, and hard braking must be avoided to prevent hydroplaning and drive-wheel skids.
Estimated Time:1m 0s