Capacity standards: what are the typical capacities for (i) a one-way 1.5 m wide sidewalk (persons per hour) and (ii) a one-way 2-lane urban road with no frontage access, no standing vehicles, and very little cross traffic (PCU per hour)?
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A1200 and 2400
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B1800 and 2000
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C1200 and 1500
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D2000 and 1200
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E900 and 3000
Answer
Correct Answer: 1200 and 2400
Explanation
Introduction / Context:Planning and traffic engineering rely on benchmark capacities to size facilities. For pedestrian sidewalks and multi-lane urban roads, conventional design manuals provide typical one-way capacities under specified assumptions (unobstructed flow, good surface, limited conflicts). This question tests recall of standard order-of-magnitude values used for preliminary design checks.
Given Data / Assumptions:
- Sidewalk width = 1.5 m, one-way pedestrian movement.
- Urban road: 2 lanes in one direction, minimal frontage access, no standing vehicles, very low cross traffic.
- Capacities expressed as persons per hour (sidewalk) and PCU per hour (road).
Concept / Approach:Pedestrian facility capacity depends on flow density, desired speed, and comfort level; a 1.5 m one-way sidewalk commonly carries about 1200 persons/hour comfortably. A one-way 2-lane urban road without side frictions typically carries about 2400 PCU/hour (≈1200 PCU per lane) under good conditions.
Step-by-Step Solution:
Match sidewalk width (1.5 m) to standard pedestrian flow rates to obtain ≈1200 persons/hour.Apply per-lane urban road capacity of ≈1200 PCU/hour; with two lanes in one direction, total ≈2400 PCU/hour.Select the pair that aligns with both computed values.Verification / Alternative check:
Cross-check with level-of-service tables; values fall within typical ranges for uninterrupted flow and adequate level of service.Why Other Options Are Wrong:
Other pairs either understate sidewalk capacity or over/understate the two-lane urban road capacity compared to norms.Common Pitfalls:
Confusing two-way sidewalk flow with one-way capacity; ignoring side frictions that can reduce practical capacity.Final Answer:
1200 and 2400