Transportation and Land Use Policy Analysis Using Integrated Transport and Gravity - Based Land Use Models

Forecasting urban futures is of great importance to many in order to ensure adequate provision of public and private services and implement policies that guide demand while mitigating negative impacts. This study produces year-2030 predictions of land use and travel conditions across the Austin-Round Rock Metropolitan Statistical Area of Texas, by integrating a gravity-based land use model (modeled on Putman's ITLUP specification) with a standard travel demand model. The land use model cycles through job, household and land consumption estimates across traffic analysis zones, before feeding forward into a contemporaneous model of travel patterns. To better understand the implications of different policies, three scenarios were generated: a business-as-usual scenario, congestion pricing-plus-carbon tax scenario, and an urban growth boundary (UGB) scenario. Results reveal how these transportation and land use policies may shape our land and travel futures, while illuminating challenges and pitfalls of the gravity-based approach to land use (including the accompanying land consumption model). Of particular interest is the fact that imposition of road pricing (roughly 5¢/mile) had almost no discernable effect on land use predictions, yet resulted in the same predicted reduction in regional VMT as the UGB policy (roughly 15%).