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Difficulty: HardBalance and Center of Gravity

Posted advisory speeds on curved highway exit ramps are calibrated to accommodate the high center of mass of fully loaded commercial vehicles, ensuring that a truck operating at the posted advisory speed will remain stable against rollover.

Answer: Answer

Answer

False
The statement is false because ramp advisory speeds are calibrated around passenger car dynamics. Elevating a vehicle's center of mass drastically lowers its rollover threshold, making it possible for a top-heavy commercial vehicle to tip over at or below the posted curve advisory speed.

Step-by-Step Solution

1
Analyze how ramp advisory speeds are established under standard roadway design guidelines.
Highway advisory speeds are calibrated to provide safe cornering margins for passenger automobiles with low centers of gravity.
Understanding the design baseline identifies why posted advisory speeds do not guarantee safety margins for commercial motor vehicles.
2
Evaluate the mechanical effect of cargo height on vehicle roll stability during lateral acceleration.
An elevated cargo mass height significantly reduces the lateral acceleration required to initiate a rollover.
Centrifugal forces acting on a high center of mass generate a substantial overturning moment around the outer trailer tires.
3
Assess the validity of the premise regarding truck stability at the posted speed.
Commercial vehicles carrying high-center-of-mass cargo can overturn at or below the posted ramp advisory speed without skidding.
Because the roll threshold of an elevated-load truck is lower than the speed limit calibration, the statement is false.

Key Concept

Center of Gravity Elevation and Ramp Rollover Thresholds
Estimated Time:1m 15s
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Topics

Balance and Center of Gravity

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