Estimating Mobile Source Emissions Benefits from Land Use Change - A Review of the State of the Practice

During 2004-2005, the Federal Highway Administration (FHWA) contracted with a private consulting firm to conduct a review of the state of the current practice of estimating the changes in mobile source emissions from land use changes. The study systematically reviewed over 50 independent research items; conducted numerous interviews with various public and private agencies including US EPA and FHWA Division Offices; and formulated a taxonomy of the existing methodologies available to metropolitan planning organizations and other agencies to address this issue. The study concluded with a description of the obstacles in the areas of travel demand modeling, emissions modeling, research deficits, and organizational barriers that would need to be breached in order to substantially improve the state of the practice. Simple elasticity-based models are the near-universal form of estimating change at this point, but the various context-related issues of the environment make these models very difficult to calibrate with any degree of surety. This paper reviews the state of the practice discovered during this exercise and highlights some of the methodological barriers and recommendations to overcoming these obstacles. An additional review of the literature produced since the study was completed at the beginning of 2005 will also be conducted. The paper intends to provide the audience with a better grasp of the current methodological issues, applied research, and the general approach to estimating mobile source emissions from land use change.