Traffic flow terminology: the maximum number of passenger cars that can pass a point in one hour under ideal roadway and traffic conditions is termed what?

Introduction / Context:
Traffic engineering distinguishes between theoretical limits and practical service levels. Understanding capacity definitions clarifies planning targets versus operational realities. Under ideal conditions (uninterrupted flow, uniform drivers and vehicles, good weather, proper geometry), the theoretical maximum flow is called the basic capacity of a lane.

Given Data / Assumptions:

• Passenger car units (PCU) concept applies; mix reduced to passenger-car equivalents.
• Ideal conditions imply no bottlenecks, adequate widths, no gradients, and no impediments.

Concept / Approach:
Basic capacity (also called theoretical capacity) is the maximum hourly volume achievable in one lane with ideal geometry and control. In contrast, “possible capacity” is colloquial and not a standard term; “service volume” refers to practical volumes at chosen Levels of Service; “traffic density” measures vehicles per kilometre per lane; and “peak-hour factor” adjusts hourly volumes for within-hour fluctuation.

Step-by-Step Solution:
Identify the keyword “ideal conditions.” Map it to “basic/theoretical capacity.” Select “Basic capacity of a traffic lane.”

Verification / Alternative check:
Highway Capacity concepts consistently define basic capacity under idealized assumptions, distinct from design service volumes that incorporate safety margins and variability.

Why Other Options Are Wrong:

• Traffic density: a state variable, not a rate.
• Possible capacity: undefined, non-standard.
• Service volume, PHF: operational metrics, not the ideal maximum per se.

Common Pitfalls:

• Using basic capacity directly for design without LOS considerations, leading to over-optimistic performance expectations.

Final Answer:
Basic capacity of a traffic lane.