CDL Combination Vehicles TestDriving Combination Vehicles SafelyEasy
A commercial driver operating a combination vehicle is approaching a sharp curve on a rural highway. The posted speed limit for the highway is 55 MPH, but there is a warning sign indicating a recommended speed of 30 MPH for the curve. To safely navigate this curve, what is the best course of action?
- AIncrease speed slightly to maintain momentum through the curve, reducing the chance of a jackknife.
- BMaintain the highway's posted speed limit of 55 MPH, as it is the legal maximum.
- CSlow down to the recommended speed of 30 MPH before entering the curve and accelerate gradually upon exit.
- DBegin braking only after entering the curve to assess the vehicle's stability.
Show answer & explanationAnswer & explanation
Correct answer: C. Slow down to the recommended speed of 30 MPH before entering the curve and accelerate gradually upon exit.
Reducing speed before entering a curve is crucial for maintaining control of a combination vehicle. The recommended speed sign indicates the safe speed for that specific road condition, especially for larger vehicles. Accelerating gradually upon exit helps to stabilize the vehicle.
Why the other options are wrong
- A. Increasing speed in a curve is extremely dangerous and significantly increases the risk of rolling over or losing control.
- B. Maintaining the highway speed limit in a sharp curve with a lower recommended speed is dangerous and can lead to loss of control.
- D. Braking within a curve, especially with a combination vehicle, can shift weight and cause loss of traction or a jackknife.
Curve Speed Control
Safely navigating curves in a combination vehicle requires reducing speed before entering the curve and maintaining a controlled speed throughout.
- Always heed advisory speed signs for curves.
- Brake before the curve, not in it.
- Accelerate gently out of the curve.
Memory trick: Curve's embrace, speed's slow dance, then a gentle pace.