Rollover Risks and Hazardous Driving
Rollover Risks and Hazardous Driving tests why combination vehicles roll over and how to drive when traction, visibility, or stability is reduced. The exam emphasizes center of gravity, curve speed, liquid surge, and weather-specific control.
Rollover causes
A loaded trailer raises the center of gravity. Speed in a curve, a short wheelbase, a high load, and sudden steering all increase roll force. Liquid loads surge, shifting weight outward and making the trailer lean. The safe technique is to slow down before the curve, steer smoothly, and accelerate gently through it. Do not brake hard in a curve.
Hazardous conditions
In rain, reduce speed to avoid hydroplaning and do not use cruise control. On ice and snow, use gentle inputs, increase following distance, and use chains where required. In fog, slow down and use low beams; do not stop on the traveled lane. In high wind, reduce speed and watch for tip-over, especially with empty trailers. On downgrades, select a safe gear before the descent and use snub braking rather than continuous light braking.
Worked example
A tanker with a partial load enters a curve at the posted speed. The liquid surges, the trailer leans, and the driver brakes hard. That adds weight transfer to the front and can cause a rollover. Correct response: slow before the curve, enter below the posted speed, keep steering smooth, and let the surge settle.
Traps
Treating the posted curve speed as safe for a loaded combination; braking hard mid-curve; using cruise control on wet roads; overcorrecting after a wheel drops off the pavement.