Title: Evaluating the Effect Urban Rail Expansion on Regional Density Distribution in Portland, OR
Description: Over time, American cities have significantly decentralized and this development pattern, dubbed ‘sprawl’, has come to be seen as a costly and inefficient development pattern that should be limited. In urban planning literature, sprawl is seen as inherently connected to a car centric physical environment. This puts improving accessibility via alternative transportation modes at the forefront of many solutions to sprawl. Transit availability and likewise transit success is seen as inherently connected to sufficient urban density. Sprawl is a regional problem because spatial dispersion goes beyond the current limits of jurisdictional regulations. As regions attempt to design effective strategies to navigate the problems created by urban sprawl, they frequently consider expanding their transit systems as an incentive for more concentrated development. This thesis examines the effectiveness of investing in new transit infrastructure, particularly fixed rail transit such as light rail and commuter rail, as a regional strategy to increase urban density by exploring the changes that have occurred in Portland, OR over the course of 20 years as they have rapidly expanded their transit system.

There are three stages of analysis. First, descriptive statistics provide an overview of trends in metropolitan wide density versus the transit shed, defined as within 2 miles of any current light or commuter rail station. Secondly, the analysis uses hot spot analysis to examine whether Portland’s population, employment, and labor density are clustered and where relatively high density clusters changed between 1990, 2000, and 2010. Finally, bivariate and multivariate regression models were built to measure whether there was a statistical association between density and fixed rail expansion by looking at how density relates to proximity to downtown, light rail stations, and transfer points. If transit expansion causes regional density concentrations to adjust towards transit, then the regression should show an increasingly positive relationship as the transit system was expanded. The research hypothesis was that areas around rail transit stations will show an increasingly positive association over the study period.

Additionally, that transfer stations where more than one line connect should show greater explanatory power and a stronger positive relationship.