Since we’ll be seeing more roundabouts in our city and, well, folks are very reluctant to change here’s a video from Carmel, Indiana which explains how roundabouts increase safety but yet can maintain a higher flow of cars without needing to build more lanes:
Here’s an excellent graphic which shows the fewer conflict points that exist in a roundabout compared to a traditional signalized intersection. Of course the more potential conflict points the higher the likelihood for a collision.
And another from the Federal Highway Administration:
That brochure also cites the fact that roundabouts reduce severe crashes by 78-82%.
Blogging Bayport Alameda 
The video says much about improving traffic flow, says nothing about improving pedestrian safety. Keeping traffic moving & pedestrian safety are conflicting goals.
Video does mention bike lane (for an entire 2 seconds) which would be a positive good if it were part of our roundabout plans, but so far there is no mention of that.
I thought improving pedestrian safety was a priority. Things change, I guess.
Comment by dave — March 8, 2023 @ 6:47 am
I’m sure the engineers and planners in Alameda have changed and no longer care about pedestrian safety like you said. The alternative is you are out of your element and exceedingly wrong, which we know is not possible.
Comment by cw — March 8, 2023 @ 8:49 am
Look at the roundabouts in that video from Indiana. You will see ZERO pedestrians, not a single one, and you will see significant additional acreage devoted to intersections for cars vs 4 way intersections.
Like you I am flummoxed by the exclusion of pedestrian safety, which I thought was a stated goal of the city. Also baffled by the commitment of more land area for auto use, which runs counter to stated goals.
The Fernside/Tilden plan posted yesterday does nothing to improve pedestrian safety, and much to worsen it. Why are we doing this?
Comment by dave — March 8, 2023 @ 9:06 am
I’m a fan of roundabouts and I believe in the data. I do get nervous about crossing them as a pedestrian. I know there’s a higher survivability because the speed at point of impact will be lower, plus fewer conflict points overall. But I’m still nervous that a car exiting a roundabout might not be watching out for pedestrians. It’s a fair anxiety to have.
Comment by Reality — March 8, 2023 @ 2:23 pm
Roundabouts increase bicycle accidents by 27% according to a Belgian cycling study. The reason is the increase in “merge” points with traffic and StreetsBlog adds that roundabouts actually scare people away from cycling. Psychologists call it “inattentional blindness” when drivers fail to register a cyclist right next to them leading to collisions.
Comment by Really — March 8, 2023 @ 8:47 am
Actually, the studies show that it depends on how roundabouts are constructed. If they have protected bike lanes, signage and lights for pedestrian crossings and other improvements, the decrease in cycle and pedestrian accidents is significant. The takeaway is, poorly designed roundabouts can in actuality and perception be more dangerous to non-vehicle users, but well designed roundabouts are safer for everyone. Lets make sure our local roundabouts are designed safer for everyone
https://www.smartcitiesdive.com/ex/sustainablecitiescollective/roundabout-safety-mixed-results-pedestrians-cyclists/122461/
https://usa.streetsblog.org/2022/09/30/not-all-roundabouts-are-created-equal-when-it-comes-to-bicycle-safety/
https://www.usu.edu/today/story/roundabouts-not-as-safe-for-cyclists-new-research-says
Comment by notadave — March 8, 2023 @ 9:57 am
Has anyone looked at what the city of Lafayette is doing with Olympic Blvd and Pleasant Hill Road? A well-known local cyclist was killed in an accident there and that seems to have been the impetus to add new barriers and lane restrictions to the existing roundabout design.
We use this roundabout weekly on the way to Mom’s house and it works well. You do see a few drivers who don’t understand right of way rules, but that was also the case when it was a four-way stop. There are some few people who lose their minds and their manners when they get behind the wheel.
Comment by 1jamesr1 — March 8, 2023 @ 10:08 am
It wasn’t very long ago the city was focused on Vision Zero, now it’s got a plan on the table to degrade pedestrian safety via roundabouts.
One of the stated goals of the Park & Webster road diets was to slow traffic. Some at city hall and on these pages were saying redesigning streets would obviate the need for traffic enforcement. Now we’re preparing to spend several million to speed up traffic which is already dangerously fast due to lack of enforcement.
The city has in recent years made bike lanes a priority (which is long overdue) and has added some, but inexplicably left them out of our two main commercial streets. And not only did these redesigns ignore critical bike lanes, they also came out a botched mess.
Pedestrian safety is critical. Bike infrastructure is a positive good. Both have been handled haphazardly at best, less polite adjectives are more accurate.
Did the city’s priorities suddenly change?
What the hell is going on?
Comment by dave — March 8, 2023 @ 5:54 pm
Try again, Dave!
“90 percent reduction in fatal crashes; 76 percent reduction in injury crashes; 30 to 40 percent reduction in pedestrian crashes; and 10 percent reduction in bicycle crashes.”
https://iowadot.gov/traffic/roundabouts/Frequently-Asked-Questions/Roundabouts-safety-and-efficiency#:~:text=Studies%20by%20the%20Insurance%20Institute,percent%20reduction%20in%20bicycle%20crashes
Comment by JRB — March 8, 2023 @ 6:23 pm
I suspect the idea is that the road-diet aspect of the project – narrowing to a single lane just after the bridge – will improve safety by calming and slowing traffic generally. My own hope as a frequent driver of that intersection is that the roundabout aspect of the project will help offset backups and delays this would cause by keeping the “calmed” traffic flowing more smoothly than it would through a light. I do understand your skepticism that the roundabout aspect of the project will on its own be good for pedestrians or cyclists (the research on this seems very mixed and poorly documented). My instinct is also to agree that the project as a whole looks like an expensive solution in search of a problem.
Comment by RJS — March 9, 2023 @ 8:54 am
Those injury reduction stats are mostly for car to car crashes and that’s not wrong. Turning t-bones into side swipes is less lethal.
But Take a second look at yesterday’s plan and tell me in your infinite adolescent wisdom how taking away stop light protected crossings and replacing them with unprotected, unsignaled crossings vs cars accelerating out of a turn is anything but a degradation of pedestrian safety.
Comment by dave — March 8, 2023 @ 6:51 pm
They need to build one at Mecartney & Island Dr intersection, it’s just insane
Comment by Anon — March 8, 2023 @ 8:32 pm
I’m happy for you, and I’mma let you finish, but… Roundabout may be a great song and all but Heart of the Sunrise is the best song on Fragile.
Comment by Rod — March 9, 2023 @ 1:44 pm
“Long Distance Runaround” may be a better choice
Comment by dave — March 9, 2023 @ 1:47 pm
Don’t get me wrong, that’s a great one, especially when it flows into The Fish, but nothing touches Heart of the Sunrise! South Side of the Sky comes close.
Comment by Rod — March 9, 2023 @ 2:58 pm
We should consider Dutch Roundabouts. They have outer rings for bicycles and pedestrians. It may look scary, but it works.
It could be worse. Google Swindon magic roundabout. It’s in the UK with 5 roundabouts connected by large central roundabout. If I remember correctly, the center roundabout moved in the opposite direction, i.e., the right direction for somebody from the US.
Comment by chuckle — March 9, 2023 @ 8:42 pm