Given basic capacity per lane C (veh/h), speed V (km/h), and S (m) as the sum of stopping distance and average vehicle length, the capacity formula discussed applies to which type of road facility?

Introduction / Context:
Macroscopic capacity relations express lane capacity as a function of speed and effective spacing. One such form uses V in km/h and S (m) representing the effective space headway (stopping distance plus vehicle length). This construct aligns with uninterrupted flow on multilane one-way facilities where uniform speed–spacing assumptions are more tenable.

Given Data / Assumptions:

• C = basic capacity per lane (vehicles/hour).
• V = space-mean speed (km/h).
• S = stopping distance + average vehicle length (m).
• Uninterrupted, one-way flow; driver behavior approximated by uniform spacing.

Concept / Approach:
Conceptually, capacity per lane ≈ (speed / spacing) after unit conversions. For one-way two-lane (per direction) roads, flows in the same direction allow consistent spacing assumptions and minimal opposing flow interference, matching the formula’s basis. Mixed two-way two-lane facilities have additional constraints (overtaking, opposing streams) that this simple relation does not capture well.

Step-by-Step Solution:
Interpret C ∝ V / S after converting km/h and metres to consistent units.Recognize uniform same-direction flow assumptions.Conclude applicability: two lanes moving in one direction (one-way).

Verification / Alternative check:
Highway capacity literature typically derives C = 1000 * V / S (after unit handling), which is best-suited to same-direction multilane contexts rather than bidirectional two-lane roads where passing maneuvers govern.

Why Other Options Are Wrong:

• District roads: a classification, not a flow pattern; capacity varies widely.
• Two-lane roads (two-way): opposing streams and passing restrictions violate the simple spacing premise.
• None of these: incorrect because a matching facility exists (two lanes, one-way).

Common Pitfalls:

• Using time headway without corresponding speed conversion, leading to unit errors.
• Applying one-way capacity relations to constrained two-way undivided roads.

Final Answer:
Two-lane roads in one direction (one-way)