Transportation Impact Analysis Gets a Failing Grade When It Comes to Climate Change and Smart Growth

Transportation impact analysis performed to comply with environmental impact laws (i.e., the California Environmental Quality Act or the National Environmental Policy Act) often focuses on only one perspective about potential impacts. That perspective reflects how automobile drivers view the world because of general traffic engineering practices and how traffic operations are measured using level of service (LOS). With many communities more concerned about climate change, creating livable communities, and wanting to emphasize the use of transit, walking, and bicycling, the traditional traffic engineering approach to traffic operations analysis is not effective. Worse, it can result in smart growth projects being denied due to neighborhood opposition associated with worsening LOS and not understanding the other tradeoff benefits of infill and higher density development. Instead of relying on vehicle LOS as the primary performance measure in transportation impact studies, agencies need to consider the tradeoffs between LOS and other important community values and other modes. This paper will present a new paradigm for transportation planning and impact analysis that reflects the inherent tradeoffs associated with vehicle travel, urban development form, and the treatment of other modes. The new paradigm will reflect a fundamental change in our current thresholds based analysis approach and it will demonstrate new analysis methodologies that focus on the following: • improving person-capacity of our transportation system • accurately describing transportation tradeoffs with other community values such as climate change, air pollution, or the ability to walk and bike • demonstrating the effects of built environment changes on reducing vehicle travel Case studies will be used to demonstrate these state of the art analysis methodologies.