Which roadway components are directly affected by the overall width of vehicles when determining geometric and layout dimensions in design?

Introduction / Context:
Vehicle dimensions (width, length, height) are fundamental inputs to geometric design. Among these, vehicle width most obviously influences cross-sectional elements and space allocations for moving and stationary vehicles.

Given Data / Assumptions:

• Design vehicle envelopes represent typical maximum widths in the vehicle fleet.
• Safety margins and shy distances supplement the base widths.

Concept / Approach:
Lane width must exceed vehicle width with lateral clearance for steering variance. Shoulders provide recovery space and lateral clearance to fixed objects. Parking modules are set from vehicle width plus door-opening and aisle requirements. Therefore, all listed components depend on vehicle width assumptions.

Step-by-Step Solution:
Relate lane width to design vehicle width + lateral clearance.Relate shoulder width to shy distance and stopped-vehicle accommodation.Relate parking bay/module widths to vehicle width and opening clearance.

Verification / Alternative check:
Design manuals specify standard lane widths (e.g., 3.0–3.75 m) and parking bay widths (e.g., 2.4–2.75 m) based on typical vehicle widths and operating envelopes.

Why Other Options Are Wrong:

• Each of A–C is individually true; only D captures the comprehensive effect.

Common Pitfalls:

• Setting narrow lanes that reduce lateral clearance and increase side-swipe risk.
• Ignoring door swing and mirror widths in parking design.

Final Answer:
All of the above