Manual of Traffic Impact Studies : Draft

With intensification urban development and dwindling public resources, assessing the impacts of a new development (traffic impact analysis) is becoming an important planning tool for transportation engineers, so that the traffic impacts of new developments can be foreseen and effective mitigating measures can be planned using optimal allocation of the available funds. The study establishes a detailed and standardized methodology for traffic impact analysis. Although the procedure was developed for the Indiana Department of Transportation, it can be used by other transportation agencies as well with little or no modification. A new methodology for estimating the percentage of pass-by trips using a license plate survey (instead of the traditional interview survey) is presented. The report also demonstrates how Bayesian statistics can be used to update the national ITE Trip Generation data base with limited local data to derive more reliable local trip generation rates. A status report of traffic impact analysis and impact fees in various state transportation agencies has also been included; a brief discussion on impact fee structure has been incorporated.