[shared from the TDM listserv]
Hi all, a really interesting study just came out of Portland State University. They looked at vehicle speed before and after the city re-signed certain designated streets to 20 MPH (from 25 MPH). They found that average speed did not change *but *the highest speeds were reduced. And those highest-speed vehicles are disproportionately responsible for injuries and fatalities, so this change is meaningful in the Vision Zero landscape.
I think it's really interesting to see that signage changes alone do, in fact, appear to change driver behavior. And this gives me the chance to plug one of my favorite (paywall free!) academic articles https://www.sciencedirect.com/science/article/pii/S2214140517307302, which explores possible theories of change - aka mechanisms by which a 20 MPH speed limit may affect safety outcomes.
Study here https://bikeportland.org/wp-content/uploads/2020/12/pbot-20-mph-speed-study-finalv5.pdf, and overview article on Bikeportland here https://bikeportland.org/2020/12/01/report-citys-new-20-mph-signs-have-reduced-top-end-speeds-323311 .
-Jessica
*JESSICA ROBERTS* *Pronouns: she/her* Principal | *Alta Planning + Design, Inc.* *Working remotely: c**:* 503.752.4144 Portland, OR | altago.com