Dividing Highways: Barrier Effects and Environmental Justice in California

We examine the barrier effects of freeways in California. We analyze the association between freeways and nearby street network connectivity and quantify the frequency and quality of crossings—underpasses or bridges that enable pedestrians and cyclists to cross the freeway. 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.