A traffic analysis zone or transportation analysis zone (TAZ) is the unit of

geography Geography (from Ancient Greek ; combining 'Earth' and 'write', literally 'Earth writing') is the study of the lands, features, inhabitants, and phenomena of Earth. Geography is an all-encompassing discipline that seeks an understanding o ...

most commonly used in conventional

transportation planning Transportation planning is the process of defining future policies, goals, investments, and spatial planning designs to prepare for future needs to move people and goods to destinations. As practiced today, it is a collaborative process that i ...

models. The size of a zone varies, but for a typical metropolitan planning software, a zone of under 3,000 people is common. The spatial extent of zones typically varies in models, ranging from very large areas in the

exurb An exurb (or alternately: exurban area) is an area outside the typically denser inner suburbs, suburban area, at the edge of a metropolitan area, which has some economic and commuting connection to the metro area, low housing-density, and rela ...

to as small as city blocks or buildings in

central business district A central business district (CBD) is the Commerce, commercial and business center of a city. It contains commercial space and offices, and in larger cities will often be described as a financial district. Geographically, it often coincides wit ...

s. There is no technical reason zones cannot be as small as single buildings, however additional zones add to the computational burden. 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. Again these zones can change or be altered as mentioned in the first paragraph. This is done typically to eliminate unneeded areas to limit the computational burden.

References

* Miller, Harvey J. & Shih-Lung Shaw. (2001) ''Geographic Information Systems for Transportation'', Oxford University Press US. p. 248. . * Caliper Corporation. (2007) "Transcad: Traffic Demand Forecasting" {{USCensus Geography United States Census Bureau geography Transportation planning