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Tanker · Safe Driving Rules

How should a tank vehicle be taken through a curve, and how should the curve's posted speed be treated?

1.Finish slowing before the curve, then accelerate gently, and assume the posted speed may exceed what the vehicle can safely holdCorrect answer
2.Brake steadily all the way through the entire curve, timing it so the braking finishes right as the vehicle exits the far side
3.Hold a constant speed from entry to exit, matched exactly to whatever speed happens to be posted for that particular curve
4.Coast through the curve in neutral the whole way, so that no drive torque reaches the wheels at any point while the vehicle is turning

Explanation

The technique is to finish slowing before the curve and then accelerate gently through it, and to assume the speed posted for the curve may be more than a tank vehicle can safely hold. Both halves follow from the load: braking in the curve adds a fore and aft wave to the lateral one the turn is already building, a slight acceleration keeps the vehicle settled on its drive wheels, and a posted curve speed is set for ordinary traffic rather than for a tall vessel of moving liquid. 49 CFR 383.119(f) makes the effects of road grade and curvature on handling with filled, half-filled, and empty tanks a required knowledge area, but it states no speed and no procedure, so the technique is the manual's. The wrong options all keep a destabilising input going through the curve, braking into the exit or holding exactly the posted speed, or give up drive and engine control entirely by coasting in neutral.

Source: 49 CFR 383.119(f)

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