What should drivers avoid when driving downhill with a heavy truck?

When driving downhill with a heavy truck, using engine braking instead of sudden acceleration or braking is essential to maintain control and ensure safety. Sudden braking can lead to brake overheating and failure, especially with the added weight of the truck. Engine braking, which involves downshifting to use the truck's engine to help control speed, helps prevent the vehicle from gaining too much speed while descending. This technique allows for smoother deceleration and better stability on the incline, making it a critical practice for drivers of heavy trucks.

The other options could lead to potential risky situations. For instance, switching off the engine would disable power steering and brakes, making it difficult to control the vehicle on a downhill slope. Changing lanes frequently may lead to instability and accidents given the size and weight of heavy trucks, while driving only in the left lane limits maneuverability and the ability to react to changing road conditions or obstacles. All these factors underscore why the best practice is to avoid sudden maneuvers and rely on steady and controlled braking methods such as engine braking.