Assessing the Extent and Determinates of Induced Growth

Abstract

Transportation improvements affect the accessibility of places, which in turn can result in changes in land use in combination with factors that support or discourage development (such as land prices, market demand, local land use regulations, and environmental constraints). Due to the uncertainty involved in forecasting the indirect effects of transportation projects on land use, transportation agencies nationally have struggled in identifying the appropriate level of analysis for this issue, in some cases resulting in litigation and project delays. The objective of this research was to identify a Montana-specific, consistent, legally defensible, and efficient process for assessing the indirect land use and environmental effects of transportation projects for the Montana Department of Transportation (MDT). Case law, guidance documents in other states, surveys, interviews, and reviews of existing MDT environmental documents were used to develop an Indirect Effects Desk Reference. The Desk Reference provides an overview of key definitions and regulatory requirements, and provides practitioners with a step-by-step screening process to determine if further analysis is warranted. The screening process relies on information of the characteristics and location of the project readily available early in the project development process. Where detailed analysis is necessary, a detailed analysis framework process is provided in the Desk Reference that includes recommendations on the analysis methodologies most applicable to the data available in different portions of Montana. Finally, recommendations for updating the Desk Reference materials over time are presented, including a recommendation to incorporate the screening and detailed analysis frameworks in MDT’s Environmental Manual. The results of this research should be useful not only to Montana, but to other western states in the Rocky Mountain and Great Plains regions of the U.S. that share similar land use, environmental, and growth trends.