Traffic Analysis Zones

A traffic analysis zone is the unit of geography most commonly used in conventional transportation planning models. The size of a zone varies, but for a typical metropolitan area, a zone of under 3000 people is common. The spatial extent of zones typically varies in models, ranging from very large areas in the suburb to as small as city blocks or buildings in central business districts. Zones are constructed by census block information. Typically these blocks are used in transportation models by providing socio-economic data. States differ in the socio-economic data that they attribute to the zones. Most often the critical information is the number of automobiles per household, household income, and employment within these zones. This information helps to further the understanding of trips that are produced and attracted within the zone. These zones can change or altered to eliminate unneeded areas to limit the "computational burden."