CDL Tanker Endorsement Practice Exam

After reaching a "safe" speed on a long or steep downgrade, what should you do with your speed?

1. Continue accelerating

2. Brake until you are traveling 10 mph slower

3. Brake until you are traveling 5 mph slower

4. Maintain your speed

The correct answer is: Brake until you are traveling 5 mph slower

When navigating a long or steep downgrade, it is essential to manage speed effectively to ensure safety and control of the vehicle. Once you reach what is considered a "safe" speed for the conditions, the appropriate action is to brake until you are traveling 5 mph slower. This helps in maintaining a speed that allows for better control and reduces the risk of overheating brakes, which can occur if you were to continue descending at the same speed for an extended period. Maintaining a slightly lower speed than the safe speed provides an added margin of safety, decreasing the need for heavy braking later if unexpected situations arise. It balances speed and control, helping to manage the weight and momentum of a tanker truck, especially considering the dynamics involved with liquid cargo, which can shift and create additional challenges during downgrades. Continuing to accelerate or braking until traveling slower than 5 mph would potentially either lead to a loss of control or, in the case of excessive deceleration, could result in an undesirable situation where the vehicle could lose momentum on the descent or require too much braking later on. Thus, slowing down by 5 mph is an effective strategy to maintain safety while descending.