Date: October 31, 2022
Author(s): Adam Millard-Ball, Benjamin Silverstein, Sierra Stevenson, Chris Barrington-Leigh
Abstract
We examine the barrier effects of freeways in California. We analyze the association between freeways and three measures of nearby street connectivity: the composite Street Network Disconnectedness index (SNDi), circuity, and the distance between crossings – underpasses or bridges that enable people to cross the freeway. We also assess the quality of a sample of these crossings for pedestrians and cyclists. We find that barrier effects are most pronounced in communities of color. We also find that even where crossings exist, they are unpleasant or even hazardous for pedestrians and cyclists because of high-speed traffic on on- and off-ramps, and because large volumes of traffic are funneled through a small number of crossings rather than being distributed over a wider network.
About the Project
The racist legacy of freeways has come into stark focus in the past year. This research focuses on one specific impact of freeways: neighborhood severance. Freeways disrupt the neighborhood street grid, creating particular hardships for pedestrians who must take circuitous routes to access transit and to walk to stores, schools, and other destinations. The impacts of disconnected streets on walking and public health are well documented (e.g. Handy 2003; Marshall et al. 2014; Barrington-Leigh and Millard-Ball 2019). But the environmental justice dimension of connectivity has remained unexplored, as has the link between most academic studies of street connectivity and local planning efforts. The research team will test the hypothesis that, while freeways disrupt street networks everywhere, the severance effects are greatest in BIPOC communities. This injustice might arise if White residents have more political voice to advocate for a denser mesh of local streets that cross the freeway, or to cancel a freeway proposal altogether.