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Difficulty: MediumSpeed on Curves and Downgrades

Yellow advisory speed signs posted beneath curve warning signs establish safe limits primarily for passenger vehicles; therefore, a commercial motor vehicle with a high center of gravity can roll over even when traveling at the posted advisory speed.

Answer: Answer

Answer

True
Advisory curve speed signs are engineered for passenger cars with low centers of gravity. Because commercial trucks have a substantially higher center of gravity, centrifugal force can tip a heavy vehicle over at the posted advisory speed even on dry pavement.

Step-by-Step Solution

1
Identify the vehicle baseline used by traffic engineers to set advisory curve speeds.
Advisory curve speeds are calculated for passenger vehicles with low centers of gravity.
Highway design guidelines establish advisory limits around typical passenger car stability rather than loaded commercial vehicle configurations.
2
Assess the effect of centrifugal force on a high center of gravity commercial vehicle.
A high center of gravity generates severe lateral tipping moments during curve negotiation.
Elevated cargo weight increases the lever arm for centrifugal force, causing the vehicle to tip over before its tires lose traction.
3
Determine safe driving practice for commercial vehicles approaching curve advisory signs.
Commercial drivers must reduce speed significantly below the posted advisory speed before entering the curve.
Navigating a sharp curve at or above the posted advisory speed creates an immediate rollover danger for heavy trucks.

Key Concept

Curve Advisory Speed Limits and Rollover Physics for Heavy Vehicles
Estimated Time:45s
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Topics

Speed on Curves and Downgrades

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