Rail-transit-induced gentrification and the affordability paradox of TOD

Numerous studies have shown that rail transit has a positive effect on raising property values and tax revenues. Such an effect is widely viewed as an economic benefit for property owners and is key to justifying the high cost of building rail transit infrastructure. In recent years, however, concerns have been raised about rail transit acting as a gentrification trigger and causing the affordability paradox. In this study, I evaluate whether rail transit in suburban Portland caused neighborhood gentrification and reduced home affordability through a longitudinal quasi-experimental design. I use the propensity score matching method to identify control neighborhoods for rail-transit-served neighborhoods. I then make pretest-posttest comparisons between rail-transit served neighborhoods and their control neighborhoods at multiple observation points. In general, I did not find consistent evidence for rail-transit-induced gentrification in suburban Portland. I did not find evidence that rail transit reduced home affordability for tenants and home owners in rail transit-served neighborhoods either. I observed more changes in the neighborhoods served by the Eastside line (the oldest rail transit line in Portland) than their control neighborhoods in the past three decades: socially, they attracted older and less-educated population; physically, they experienced densification and faster increases of the share of rental units in their housing stock. Rail transit was more likely to be installed along low-income neighborhoods in suburban Portland, confirming the necessity of constructing appropriate control neighborhoods while evaluating the neighborhood and social effects of rail transit.