In highway design, which aspects are directly influenced by vehicle weight (axle loads and gross mass) during planning and structural design?

Introduction / Context:
Vehicle weights—expressed as axle loads and gross vehicle mass—drive several design decisions. From pavement structural capacity to vertical alignment and bridge member sizing, these loads determine safe, durable, and economical solutions.

Given Data / Assumptions:

• Commercial vehicle axle loads as per regulatory limits.
• Target facility class and terrain known to the designer.

Concept / Approach:
Pavement thickness is selected to resist cumulative load repetitions (fatigue and rutting) caused by axle loads. Ruling and limiting gradients are chosen considering vehicle tractive effort; heavier vehicles require gentler grades to maintain acceptable speeds. Bridge design is governed by standard vehicular load models; higher weights increase member forces and deck thickness requirements.

Step-by-Step Solution:
Relate axle load spectra to pavement layer design.Relate vehicle mass and engine performance to feasible gradients (ruling/limiting).Apply vehicular load models to bridge structural design.

Verification / Alternative check:
Mechanistic–empirical pavement design explicitly uses equivalent standard axle loads. Alignment design manuals list grade limits by vehicle class and terrain. Bridge codes specify vehicular loadings that scale with assumed vehicle weights.

Why Other Options Are Wrong:

• A–D are all correct; only E captures the comprehensive influence.

Common Pitfalls:
Ignoring axle load enforcement leads to rapid pavement failure; using overly steep grades can stall heavy vehicles; under-designing bridges risks serviceability and safety.

Final Answer:
All of the above