What does the term 'demand' refer to in traffic engineering?

In traffic engineering, 'demand' specifically refers to the number of vehicles that desire to travel past a point during a given time period. This concept is crucial for understanding how traffic patterns develop, planning road infrastructure, and optimizing traffic flow. By measuring demand, professionals can assess the volume of traffic expected at certain times, which can inform decisions on traffic signal timing, road design, and capacity needs.

Understanding demand helps engineers anticipate congestion and implement measures to improve traffic operations. For instance, if demand is high during peak hours, adjustments can be made to accommodate these patterns, such as adding lanes or optimizing traffic signals. This articulation of demand directly impacts the effectiveness of traffic management strategies and road safety measures.

In contrast, the other options address different aspects of traffic engineering such as capacity, which pertains to how many vehicles a roadway can handle, average speed, which reflects traffic performance rather than desire to travel, and accidents, which are not related to the demand for travel but rather outcomes of traffic conditions. Thus, the focus on demand is key to effective traffic planning and management.