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Difficulty: MediumSpeed on Curves and Downgrades

Posted advisory speeds on highway curve warning signs represent the safe traveling speed for all vehicles, meaning a fully loaded commercial truck can safely negotiate the curve at the posted advisory speed under normal, dry road conditions.

Answer: Answer

Answer

False. Advisory speeds on curve signs are set for passenger cars, and heavy commercial vehicles must reduce their speed below the posted advisory speed before entering a curve to prevent rolling over.
The statement is false because posted advisory speeds on curve warning signs are determined based on passenger vehicle dynamics. Commercial motor vehicles have a substantially higher center of gravity and can roll over at posted advisory speeds. Safe operation requires commercial drivers to slow down to a speed below the posted advisory speed before entering the curve.

Step-by-Step Solution

1
Determine how highway advisory curve speeds are established and calibrated.
Posted advisory speeds are determined using the handling capabilities and low center of gravity of standard passenger cars.
Highway design standards establish curve advisory speeds based on passenger vehicles, not heavy commercial motor vehicles.
2
Analyze how commercial vehicle physics differ from passenger vehicles on curves.
A commercial truck has a much higher center of gravity and is vulnerable to centrifugal force and rollover at standard advisory speeds.
The higher center of gravity makes commercial vehicles susceptible to rolling over even when traveling at or slightly below the posted advisory speed.
3
Apply safe CDL speed management procedures for curve negotiation.
Commercial drivers must reduce vehicle speed below the posted curve advisory speed prior to entering the turn.
Slowing down in a straight line before entering the curve ensures the vehicle remains stable and avoids rollover or tire skid.

Key Concept

Posted curve advisory speeds are calibrated for passenger cars; commercial motor vehicles must slow down below the posted advisory speed before entering a curve to avoid rollover.
Estimated Time:45s
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Topics

Speed on Curves and Downgrades

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