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Difficulty: MediumSpeed on Curves and Downgrades

Posted speed limits on highway curve advisory signs are established for passenger automobiles under ideal conditions, requiring commercial motor vehicles—especially those carrying high-center-of-gravity loads—to negotiate the curve at speeds below the posted advisory speed to prevent rolling over.

Answer: Answer

Answer

True. Commercial motor vehicles must travel below posted curve advisory speeds because those advisory limits are engineered for passenger cars, and a commercial truck's higher center of gravity significantly increases rollover risk.
Commercial motor vehicles have a substantially higher center of gravity than passenger cars, making them prone to rollover from lateral centrifugal force. Because curve advisory signs are set using passenger car baselines, safe commercial driving requires reducing speed below the posted advisory speed prior to entering the curve.

Step-by-Step Solution

1
Identify the engineering baseline for posted curve advisory signs.
Advisory speeds posted on curve warning signs are calculated based on passenger car dimensions, traction, and low centers of gravity.
Recognizing the design baseline of roadway signage prevents overestimating vehicle stability.
2
Evaluate the stability and physics of commercial motor vehicles compared to passenger cars.
Commercial vehicles carry heavier loads with a significantly higher center of gravity, making them far more vulnerable to centrifugal force and lateral rollover.
Understanding center-of-gravity dynamics dictates proper cornering safety protocols.
3
Determine the necessary speed adjustment prior to curve entry.
Commercial drivers must slow to a speed below the posted advisory limit before entering the turn.
Slowing down in advance prevents the need for dangerous mid-curve braking and eliminates rollover risks.

Key Concept

Advisory Speed Thresholds and Rollover Physics on Curves
Estimated Time:45s
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Topics

Speed on Curves and Downgrades

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