Define "capacity" in the context of a roadway.

In the context of a roadway, "capacity" is defined as the maximum number of vehicles that can pass a given point within a specific time period. This definition is rooted in traffic flow theory, which quantifies how many vehicles can effectively traverse a section of roadway without causing congestion. Capacity is influenced by various factors including roadway geometry, lane width, traffic composition, and control measures (such as traffic signals and stop signs).

Understanding roadway capacity is crucial for traffic engineers when designing roadways, evaluating existing conditions, and planning for future traffic demands. It helps in optimizing traffic flow, reducing delays, and enhancing safety for all road users.

The other choices provided do not accurately capture the essence of capacity as understood in roadway operations. For instance, average speed relates to how fast vehicles are traveling rather than how many can pass in a given timeframe. The total length of time vehicles occupy the roadway pertains to traffic delay or queue length, not capacity. Lastly, the minimum number of vehicles allowed on a roadway does not relate to the concept of capacity; it is irrelevant to the flow and operational characteristics of the roadway. Thus, the correct choice is the one that directly relates to the volumetric measure of traffic flow capacity.