This week GSPP first year MPP students had the opportunity to prove their research chops in the rite of passage called the "48 hour project," wherein we had between 0930 Tuesday and 0930 Thursday to write a policy memo on a randomly selected topic. I had the great luck of getting the policy issue of Berkeley's traffic circles, on which almost no person in Berkeley is lukewarm. Everyone is fired up about these European invaders to our conventional grid-pattern streets and intersections. I had the continued great luck of getting on the phone the Berkeley mayor's chief of staff, the head of the Berkeley firefighters' union, assorted city planners in assorted cities and, in a final coup, the transportation engineer (no longer at the City of Berkeley) behind the installation of 31 traffic circles between 2003 and 2007. Now, in the aftermath of our 48-hour ordeal, I've found many among my fellow students curious about what I found regarding Berkeley's mysterious traffic circles (what John Ellwood calls "crop circles").

To summarize, there are three learning curves involved in a traffic circle's life, and one important principle behind them.

Learning curve #1 - a city learns how NOT to install a traffic circle. San Francisco recently plopped a circle in a neighborhood without community consent, and promptly were forced to remove it. Berkeley has continued to install circles only in neighborhoods that demand them, so the well-organized (read: wealthier) communities get circles, regardless of the need for traffic-calming in that neighborhood's streets. There are better ways to install traffic circles.

Learning curve #2 - local drivers learn how to yield to moving traffic and go in a counter-clockwise direction around a circle to exit onto the street you want (yes, even when you only want to turn left).

Learning curve #3 - local drivers who tend to speed learn how to drive recklessly around the circle, swinging wide into the crosswalk. This is a problem that some cities have addressed by putting speed bumps around the traffic circle (which brings up a whole host of other issues).

The important principle behind traffic circles is this: what makes you feel safe when you are driving is not the same thing as what reduces traffic accidents. Nearly every non-engineer I talked to said that traffic circles make them nervous. Well, traffic circles reduce accidents by 70-80%, partly because all traffic is moving in one direction, eliminating the worst angles for accidents (head-on and T), and partly because when you are nervous, you are more alert, and a better driver.

I get more into all of this in my memo,which - though far from perfect - was pretty entertaining to write, and I hope somewhat entertaining to read. If you never heard about the HILARIOUS 2005 tree-napping of a Bald Cyprus from a Le Conte neighborhood traffic circle, or have ANY questions about traffic circles running around in your head, definitely check out my memo (a PDF download).

I hope other students who had good 48-hour project experiences will follow suit and post their memos... Just let me remind the gentle readers of this blog: the 48-hour memos were written in 48 hours!