CDL Tanker Endorsement Practice Exam

When should you be especially cautious when driving smooth bore tankers?

1. During long-distance trips

2. When starting or stopping

3. When driving on smooth roads

4. During inclement weather

The correct answer is: When starting or stopping

Being especially cautious when starting or stopping while driving smooth bore tankers is critical due to the behavior of the liquid cargo inside the tank. Smooth bore tankers have a cylindrical shape that allows the liquid to move freely inside. When you accelerate or decelerate, the liquid shifts, creating a phenomenon known as "liquid surge." This movement can cause the vehicle to become unstable, making it more difficult to control. At low speeds, such as when starting or coming to a stop, even a small amount of liquid surge can result in significant lateral forces that may lead to jackknifing or tipping the tanker. Therefore, it is crucial to understand the dynamics of your cargo and adapt your driving techniques accordingly, ensuring smoother transitions when starting and stopping to maintain stability and safety on the road. Being cautious during long-distance trips, on smooth roads, or during inclement weather is also important, but the specific risks associated with starting and stopping make those situations particularly critical for smooth bore tanker drivers.