In the first step of planning travel for a city, what do we call figuring out how many trips begin and end in each area?

In the first step of planning travel for a city, figuring out how many trips begin and end in each area is called Trip Generation. Trip Generation is the initial stage of the classic four-step travel demand model, which transportation planners use to forecast future travel patterns. This process involves calculating the total number of trips produced by, meaning originating from, and attracted to, meaning destined for, specific geographic units within a study area. These geographic units are known as traffic analysis zones, or simply zones, which are defined areas like a neighborhood or a commercial block used for collecting and analyzing travel data. For example, Trip Generation would determine that a particular residential zone produces 100 trips and attracts 20 trips during a specific time period, while an employment zone might produce 15 trips and attract 85 trips during the same period. This step quantifies the overall travel demand generated by different land uses and socioeconomic characteristics within each zone, establishing the base volume of travel before considering where those trips specifically go or which mode of transport people use.