UCLA Institute of Transportation Studies

In the United States, local governments typically evaluate the transportation impacts of new development based on the expected effects of the development on nearby traffic flows. These flows are most often measured in terms of “level-of-service,” or LOS, from “A” (free flow) to “F” (forced flow). If a traffic impact analysis (TIA) finds that the LOS on streets and intersections near the proposed development will degrade below a certain threshold, the project developer may be required to undertake mitigation efforts, including funding nearby transportation system improvements to lessen the projected traffic delays occasioned by the new development and/or reduce the scale of the proposal — or they may risk the project not being approved at all. LOS mitigation frequently ignores travel via modes — such as walking, biking, scooters, or public transit — other than motor vehicles. This emphasis on nearby traffic effects and motor vehicle mobility can discourage development in already built-up areas and, in doing so, ignore both the project’s regional effects on travel and traffic and the economic, social, and environmental benefits that arise from agglomerations of activities