Traffic Study Information

Purpose of a Transportation Impact Study

A Transportation Impact Study (TIS) is conducted to evaluate the impacts of proposed developments on an existing transportation roadway system and to assist both public and private planners in making decisions with regard to the allowance or disallowance of these proposed developments.  These studies evaluate the changes in traffic attributable to the proposed development and translate them into transportation impacts in the vicinity of the proposed development.  Most studies define the on-site and off-site transportation system improvements needed to accommodate the additional traffic generated by the development. These recommended transportation improvements are termed mitigation measures.

Basic Elements of a Transportation Impact Study

A TIS can be assembled in different formats. Click here for a sample report outline of a TIS. This outline is general and can be expanded or contracted depending upon specific issues and local requirements.

Transportation Impact Study Thresholds

A TIS should be conducted when a proposed development exceeds 100 vehicle trip ends during the highest weekday peak hour.  Click here to see the size of some typical generators that achieves 100 vehicle trip ends.

Potential Transportation Related Mitigation Measures

Once transportation impacts are identified in the study, a number of potential mitigation measure options exist to alleviate these impacts.  Click here for information on some potential transportation related mitigation measures.

ITE Bookstore Recommended Reference Documents

The following TIS reference documents are recommended from the ITE Bookstore for use in the preparation and review of a TIS.

1. Transportation Impact Analyses for Site Development: An ITE Proposed Recommended Practice

2. Trip Generation, 11th Edition: An ITE Informational Report

Click here for TSITE’s Did You Know TIS Brochure.