Introduction to the City's Transportation Impact Review Process

The City's transportation impact review process is developed to guide traffic consultants and developers throughout project development and to ensure potential impact on traffic, parking, transit usage and pedestrian amenities. Mitigation measures are developed in accordance to the policies of the General Plan Mobility Element.

The City's overall approach to analyzing project impacts and cumulative impacts is consistent with the California Environmental Quality Act (CEQA).

Existing traffic conditions are first documented. Normally this is accomplished with new traffic counts in order to provide the latest information. Then future traffic growth is estimated.

A future baseline condition is forecast for the target year of completion for the proposed development project. This is called the "Future Without Project" condition. It represents cumulative traffic growth from approved, proposed and reasonably foreseeable future development projects and sets a baseline against which specific impacts of the proposed development project can be measured.

Forecasting of this future baseline comprises two components; 1) by identifying other future development projects in the general study area that reasonably may be completed in the time frame of the subject project, and forecasting traffic growth from those projects. These projects are often called "related" projects or "cumulative" projects; and 2) by defining an "ambient" growth factor representing traffic growth from outside the study area. Adding traffic growth from the related projects, and the "ambient" traffic growth, to the existing traffic volumes, produces a forecast of future traffic conditions without the proposed project - called the cumulative baseline condition, or Future Without Project condition.

The final step is to determine the traffic growth from the subject project and the impacts it may cause. Because traffic growth from other development projects is also considered (as described above), this impact analysis represents the cumulative impacts of the subject project - that is, it represents the impacts of the project taking other cumulative projects into account.

This approach is consistent with CEQA and is the approach used by the vast majority of jurisdictions in Southern California.

Preparation Guidelines

Transportation Impact Review: Current Practice & Guidelines, Aug. 2005

Guidelines for Transportation Review of Projects, September 2004

Scoping for Traffic Study MOU (available upon request)

New E-Library!

Traffic impact reports (in Acrobat PDF format) are available upon request. Documents will continue to be added to this E-Library periodically. For further information or assistance, please contact:

Conrad Viana, P.E.

Transportation Engineer

Tel: (626) 744-7424

Last Updated:08/23/2007 ECS