Traffic Analysis Zone

A Traffic Analysis Zone (TAZ) is the unit of geography most commonly used in conventional transportation planning models. The size of a zone varies, but for a typical metropolitan planning software, a zone of under 3000 people (residents) is common. The spatial extent of zones typically varies in models, ranging from very large areas in the outer regions to city blocks or buildings in central business districts. There is no technical reason zones cannot be as small as single buildings, however additional zones add to the computational burden. In particular, skim matrices may become very large if too many zones are used.

Zones are constructed by census block information. Typically these blocks are used in transportation models by providing socio-economic data. U.S. States differ in the socio-economic data that they attribute to zones. Most often, the most important attributes are number fo households (or residents), 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.

Zone shapes that should be avoided include narrow stripes, horse shoes or doughnuts.

# References

Content Charrette: Destination Choice Models

  • Miller, Harvey J. & Shih-Lung Shaw. (2001) Geographic Information Systems for Transportation, Oxford University Press US. p. 248. ISBN 0-19-512394-8.
  • Caliper Corporation. (2007) "Transcad: Traffic Demand Forecasting"