From Traffic Impact Analysis to Accessibility Impact Analysis: Developing and Testing a Next Generation Development Impact Analysis Tool

Research Team: Brian D. Taylor (lead), Fariba Siddiq, and Hao Ding

UC Campus(es): UCLA

Problem Statement: For decades evaluation of the benefits and costs of new development or redevelopment in urban areas has centered on the effects of development on nearby traffic flows. To address the traffic flow focus of traffic impact analyses, SB 743 directed the Governor’s Office of Planning and Research (OPR) to develop alternative criteria for measuring the impact of projects. In response, OPR proposed using vehicle miles traveled (VMT) as the most appropriate metric to evaluate a project’s transportation impacts. While most observers agree that a new focus on VMT offers a more holistic picture of transportation impact than focusing on automobile delay as measured by Level of Service (LOS), the new analytical model still centers on adjacent road networks largely distinct from how the proposed development might be expected to benefit cities generally, and agglomerations of activities specifically. A large and growing body of research argues against focusing on mobility (whether to improve the driving experience traditionally or to discourage driving more recently) in favor of focusing on access to destinations when evaluating the role of transportation systems in urban systems. These works by eminent transportation scholars suggest that the move in California from LOS to VMT is a step in the right direction, but not the last step. A more complete and practical accessibility impact analysis tool is needed to better understand the effects of development on urban systems.

Project Description: This research project builds on a series of recent projects and papers at UCLA ITS examining the shift from mobility-focused to access-focused in evaluating the causes and (especially) consequences of traffic congestion on the functioning of cities and their economic agglomerations. This work has turned traffic impact analysis on its head by considering how the spatial arrangement of destinations makes it easier or harder to access them -- regardless of the traffic speeds on adjacent roadways.

Status: Completed

Budget: $40,000