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Difficulty: HardSpace Overhead

When a long-wheelbase commercial vehicle combination crosses a sharp vertical crest (roadway hump) directly beneath an overhead structure, the effective overhead clearance is reduced because the midsection of the trailer is elevated relative to the wheel contact points on the approach and departure slopes.

Answer: Answer

Answer

True
The statement is correct because rigid combination vehicles with long wheelbases do not flex to match roadway elevation changes. When crossing a vertical crest or hump, the front and rear axles rest on the downward slopes on either side of the apex, elevating the trailer's midpoint and diminishing overhead clearance under low-hanging structures.

Step-by-Step Solution

1
Analyze the vehicle wheelbase geometry across a vertical road crest.
Recognize that the front tractor axles and rear trailer axles occupy lower elevation points on the approach and departure slopes on opposite sides of the hump.
Roadway topography changes across vertical curves while the trailer body remains a rigid horizontal plane.
2
Evaluate the vertical displacement of the trailer's midsection.
The center span of the trailer is elevated higher relative to the apex of the roadway compared to operation on flat ground.
Bridging a convex vertical curve elevates the midpoint of a rigid span relative to the support points at the wheels.
3
Determine the impact on overhead clearance beneath the structure.
The vertical space between the top-center of the trailer and the overhead obstruction decreases, requiring greater overhead margin.
Any upward elevation of the vehicle body directly reduces the remaining clearance beneath overhead hazards.

Key Concept

Impact of vertical roadway curvature (crests and humps) on commercial vehicle overhead clearance
Estimated Time:1m 30s
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Topics

Space Overhead

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