Monday, July 22, 2024

The abstract from a September study’s report documentation page.

Debate about the installation of additional separated bike lanes is a major topic this election season. As I was planning how to vote, I was pleased to discover that the U.S. Department of Transportation just last month released a report on the effect of bike lanes separated from car traffic by flexi-posts such as the “quick-build” bike lanes here in Cambridge.

The researchers the agency sponsored at Texas A&M University studied our own Cambridge as well as San Francisco and Seattle; Denver and Austin, Texas were included as well. Across all five cities they found consistently that flexi-posts reduced crashes by 50 percent when compared to bike lanes without them.

Cambridge’s open data portal shows that in 2022 our police department reported 119 motor vehicle crashes involving a bicycle, resulting in 100 injuries and 51 hospitalizations. From 2016 to 2019 all had similar totals, while 2020-2021 had reduced traffic of all types due to the pandemic.

We can’t know for sure how much of this harm might be prevented by installing more separated bike lanes. But the DOT report lets us estimate that every 5 percent of our total bike traffic we shift from paint-only bike lanes to separated bike lanes keeps one of our neighbors out of the hospital every year. Building separated bike lanes has costs and benefits, but this benefit seemed big and surprising enough to be worth sharing with you all.

Dan Recht, Avon Hill Street

This post was updated Oct. 9, 2023, to add an image of a report abstract.