Impact of Public Transit Market Share and Other Transportation Variables on GHG Emissions: Developing Statistical Models for Aggregate Predictions

This study develops a statistical model that provides an important step towards quantifying the possible benefits that could be derived from potential reductions in greenhouse gas (GHG) emissions. In this study, only carbon dioxide (CO₂) emissions are examined since these emissions constitute 93.4% of the GHG produced in the transportation sector (Energy Information Administration, 2008). In addition, the CO₂ emissions focused on are those resulting from passenger travel and the roles of travelers’ choices within the confines of available infrastructure and existing urban form. The contributions of this study are twofold. First, an aggregate model of urban passenger travel related CO₂ emissions in U.S. urbanized areas that includes a rich set of explanatory variables is developed. Second, in doing so, the roles of policies aimed at improving the environment or enhancing the attitudes of travelers towards making environmentally favorable choices is captured through the use of a proxy variable.