Skip to Content
Streetsblog California home
Streetsblog California home
Log In
Streetsblog USA

Study: Diagonal Intersections Are Especially Dangerous for Cyclists

This week, Cambridge, Massachusetts, unveiled plans for a "peanutabout" that will make a tricky intersection with irregular angles safe for cycling. This type of design intervention could be crucial for locations that new research suggests are especially dangerous.

This new deigned for a diagnoal intersections in Cambridge includes protected bike lanes and a ? on a round-about that locals call a "peanutabout." Image via Boston Cyclists Union
At this irregular intersection in Cambridge, the city plans to improve safety with what the locals call a "peanutabout." Image via Boston Cyclists Union
false

In a study published in the journal Injury Prevention [PDF], a team led by Dr. Morteza Asgarzadeh of Harvard's T. H. Chan School of Public Health found that non-right-angle intersections are especially prone to crashes that cause severe or fatal injuries to bicyclists.

Asgarzadeh and his team mapped 3,300 injury crash locations in New York city involving a motorist and a cyclist. Then they analyzed the relationship between a number of factors and injury severity, including street width, weather conditions, gender and age of the cyclist, and posted speed limit.

In most cases, researchers did not identify a significant link. But the researchers did find that a few conditions are correlated with more severe injuries.

Crashes that occurred at diagonal intersections were 37 percent more likely to result in severe injury or death than crashes at right-angle intersections. In addition, while 60 percent of bike-car crashes happen at intersection, cyclists hit by a cars on straightaways -- not at intersections -- were 31 percent more likely to be killed or severely injured. The researchers hypothesize that crashes on straightways may be more deadly because drivers are traveling at a higher speed.

They also found, not surprisingly, that cyclists struck by a truck or bus driver were twice as likely to be killed as those hit by a car driver.

Asgarzadeh concluded that the findings bolster the case for protected bike lanes, which would shield cyclists on straightaways. They also suggest planning bike routes that have more right-angle intersections and giving cyclists a dedicated signal phase at non-right-angle intersections.

More peanutabouts may also be in order.

Stay in touch

Sign up for our free newsletter

More from Streetsblog California

Automated Enforcement Coming Soon to a Bus Lane Near You

Metro is already installing on-bus cameras. Soon comes testing, outreach, then warning tickets.

April 19, 2024

Friday’s Headlines

SF plans street redesign at crash site; Santa Cruz commission still supports plan to have both trail and rail; State budget includes subsidies for fossil fuel industry; Unhoused camping; More

April 19, 2024

Legislators Tackle AV, School Zone Safety

Are AVs freight trucks ready to be deployed on California roads with no one in them?

April 17, 2024

Metro Looks to Approve Torrance C Line Extension Alignment

Selecting the relatively low-cost hybrid alternative should help the oft-delayed South Bay C Line extension move a step closer to reality

April 17, 2024
See all posts