Instead of doing our weekly shopping trip at our usual chain store, I took a trip off-island in search of a very particular ingredient on Sunday... and eventually reached Berkeley Bowl West.

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As an Alameda-based traffic engineer predicted to a newspaper 20 years ago, Berkeley Bowl West does indeed have a "power to draw a clientele from across the East Bay and beyond."

Before entering the maelstrom, I prepared myself with a brief bite and a moment watching my favorite "mini roundabout" in the entire Bay Area. (They're also called "neighborhood traffic circles.")

Physically, it's a "quick build" installation made of some plastic, some metal, and some signage. It's ugly.

The intersection of Heinz Ave and 9th St in west Berkeley. Aerial imagery (C) Nearmap, taken on Sept 2, 2024.

But the appearance doesn't matter much. What matters are the behavioral changes it induces.

By sitting in the middle of the intersection, this installation prevents drivers from traveling straight through. Instead, drivers (as well as cyclists) have to arc around the mini traffic circle:

drivers going straight need to slow as they curve around the traffic circle
drivers who want to turn are guided to arc around the traffic circle, rather than cut more directly toward their destination (potentially cutting off others in a car, on a bike, or on foot in the process)
when multiple drivers and/or cyclists arrive at the intersection at the same time, the traffic circle guides them in a circle through the intersection

These behavioral changes complement the four-way stop, adding another "layer" of protection to this intersection.

💡

In the technical lingo of traffic engineers, the stop signs are considered traffic control devices because they enable drivers to take turns — while the mini neighborhood roundabout is considered a speed control device, since it controls their speeds.

This is why if you tell a Professional Engineer that motorists are driving too fast on your street and you would like a stop sign to be installed, the engineers are duty-bound to tell you "no!" Instead, try asking for one of these mini roundabouts — or go wild and ask for a chicane.

In addition to being ugly, this mini neighborhood traffic circle is quite mini. And yet despite its small size, it has an outsized impact on driver behavior. And that's why I like it because it exists and it works:

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Mini roundabouts for Alameda... when?

As part of the Neighborhood Greenways program, the city's consultants have recently created a rendering of a vibrant — but hypothetical — mini roundabout:

Quick-Build Traffic Circle Rendering at Pacific/Chestnust

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There's an upcoming public Pacific Ave Neighborhood Greenway event on Dec. 10, from 6-7:30pm at the main library.

But personally, I find the little thing in west Berkeley more interesting than renderings. It actually exists, and it effectively helps to shape the behavior of drivers (and cyclists) at a intersection that may look small but actually sees a decent amount of traffic overall.

If you want to see the mechanics of how a mini roundabout works (and why it's way overdue to join the toolkit of street safety treatments in Alameda; and why I wish one would had been installed at Regent St/San Jose Ave on Friday evening when I watched two drivers nearly t-bone each other at the center-point of that intersection) go up to west Berkeley and grab a snack to eat while you watch.

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An update after reading some comments: If a mini roundabout feels to you like an ideal solution to a problematic spot along one of Alameda's designated Neighborhood Greenway corridors, open up the city consultants' web map and drop a pin and a comment in support of a mini roundabout.

For non-Neighborhood Greenways around Alameda, you can always mention a mini roundabout as a potential solution when filing a SeeClickFix ticket under the "Street Safety Concern" category.