Public Transit Access and Income Segregation

What are the implications of mass transit improvements for residential income segregation within cities? I observe large income differences in households' usage of and residential proximity to “fast” versus “slow” transit (e.g., subways vs. buses on shared lanes). Consistent with these observations, I propose a theoretical framework to characterize the relationship between income segregation and the spatial distribution of transit speeds and travel mode choices within cities. I find that transit improvements that would maximize transit ridership tend to reduce income segregation when improving “slow” transit but increase income segregation when improving “fast” transit.