work related to trip generation analysis is grouped under the rubric travel demand theory, which treats trip generation-attraction, as well as mode choice, route selection, and other topics. Databases The Institute of Transportation Engineers's Trip Generation Manual provides trip generation rates for various land use and building types. The planner can add local adjustment factors and treat mixes of uses with ease. Ongoing work is adding to the stockpile of numbers; over 4000 studies were aggregated for the latest edition. ITE Procedures estimate the number of trips entering and exiting a site at a given time. ITE Rates are functions of type of development based on independent variables such as square footage of the gross leasable area, number of gas pumps, number of dwelling units, or other standard measurable things, usually produced in site plans. They are typically of the form or . They do not consider location, competitors, complements, the cost of transportation, or other factors. The trip generation estimates are provided through data analysis. Many localities require their use to ensure adequate public facilities for growth management and subdivision approval. In the United Kingdom and Ireland, the TRICS database is commonly used to calculate trip generation. References See also Hypermobility (travel) Microsimulation Traffic engineering Traffic flow Transportation planning