CDL Combination Vehicles TestDriving Combination Vehicles SafelyEasy
A driver of a combination vehicle is preparing to enter a curve on a rural highway. The posted speed limit for the straightaway leading to the curve is 65 mph. The driver observes a warning sign indicating a recommended curve speed of 35 mph. What is the most crucial action the driver should take before entering the curve?
- AReduce speed to 35 mph or less before entering the curve, and then accelerate gently through it.
- BApply the trailer hand brake lightly while navigating the curve to maintain control.
- CIncrease speed slightly to use centrifugal force to stabilize the vehicle through the curve.
- DMaintain 65 mph until halfway through the curve, then apply firm braking.
Show answer & explanationAnswer & explanation
Correct answer: A. Reduce speed to 35 mph or less before entering the curve, and then accelerate gently through it.
Reducing speed to a safe level before entering a curve is critical for combination vehicles. This allows the driver to maintain control and avoid rolling over, especially given the higher center of gravity and articulation points.
Why the other options are wrong
- B. Using the trailer hand brake alone can cause the trailer to swing or jackknife.
- C. Increasing speed in a curve, particularly with a combination vehicle, significantly increases the risk of a rollover.
- D. Braking heavily within a curve, especially with a combination vehicle, can cause a jackknife or rollover.
Safe Curve Negotiation
Always reduce speed to a safe level *before* entering a curve, especially with a combination vehicle, to prevent rollovers and maintain control.
- Decelerate before the curve.
- Maintain steady speed or gentle acceleration through the curve.
- Avoid braking in the curve.
Memory trick: Slow Before You Go, Smooth as You Flow.