Santa Cruz Roundabout

How to bike through the Santa Cruz roundabout.

Santa Cruz roundabout

Roundabouts or traffic circles are installed to improve traffic flow and capacity at an intersection. A roundabout recently replaced the intersection where Center, Pacific, West Cliff and the entrace to Depot Park all come together. There has been grumbling from the locals, but roundabouts are proven to improve safety: There’s a 39% decrease in crashes after roundabouts are installed in an American intersection, with a 27% reduction in property damage only accidents. When there are collisions, they tend to be less harmful, with a 76% decrease in injury crashes and a 90% decrease in fatalities or disabling injuries. Collisions involving pedestrians drop by 30% to 40%. For cyclists, there is a lower speed differential between cyclists and motorists in a roundabout — cyclists and motorists are traveling at about the same speed through the roundabout.

In Santa Cruz, a secondary purpose of this traffic circle and another that will be installed at the wharf entrance is to help direct beach traffic to and through the Santa Cruz downtown.

Traffic signals or roundabouts?

When Santa Cruz first began looking into traffic controls for these locations, they considered traffic lights. Their engineering consultant questioned the utility of lights at these locations, however, which have up to 200 cyclists and over 1,000 pedestrians crossing per hour on the weekends. The standard engineering models used to predict traffic flow through signalized intersections don’t work with Santa Cruz’s level of cyclist and pedestrian traffic, and the consultant did not believe pedestrians and cyclists would be willing to wait two minutes for the next light. Traffic signals could also increase risk for cyclists and pedestrians by creating fast moving ‘platoons’ of traffic as drivers race to the next intersection.

Santa Cruz decided on roundabouts and received ARRA construction funds last fall. The Pacific Avenue / Center Street roundabout is essentially complete, and I’ve watched people use this roundabout in their cars, on bicycles, with wheelchairs and with their feet since early April.

HOWTO

Traffic engineers in Europe and the United States learned that directing cyclists to the outside portion of a roundabout increased danger to the cyclist. Modern design guides recommend ending bicycle lanes before the circle so that cyclists either (1) merge with traffic and use the entire lane the same as any other vehicle, or (2) move over from the bike lane onto the sidepath and travel across like a pedestrian. Curb cuts are positioned at the bike lane end to facilitate moving onto the sidewalk.

This Flash animation from the city of Honolulu bicycle program describes the best way for cyclists to enter and travel across a roundabout.



In Santa Cruz, some cyclists complain about the bike lane striping that seems to direct cyclists onto the sidewalk. During the half hour I watched cyclists at this traffic circle, about 70% to 80% of them ignored the solid stripe and entered the flow of traffic. With the slow speed of traffic here, this is very doable for most adult cyclists. The cyclist in front of me in this video hugged the right edge of the circle — I recommend against that, but in that part of Santa Cruz I doubt if there’s much actual risk in collision from doing that.



2 Comments

  • June 14, 2011 - 1:45 am | Permalink

    These things freak me out, but maybe it’s just because I’m not used to them. I feel like they’re setting me up to be hit by cars, but here’s hoping I’m wrong. Great post!

  • Eamonn
    June 15, 2011 - 10:20 pm | Permalink

    Try the Magic Roundabout in Swindon, England. Six mini-roundabouts arranged in a circle!

    Seriously though, roundabouts are okay for cyclists as long as the radius is small enough to slow the cars down to the speed of a cyclist. A larger radius can cause a lot of problems though, as anyone who has tried to navigate roundabouts on a bike in the UK can attest. A larger radius means faster-moving cars, making it very difficult for a cyclist to accelerate out into any gaps in traffic.

    On a two-lane roundabout where I’m passing more than one exit, I like to hug the inside curb and let any motorists pass me on the right if they’re exiting before me.

  • Leave a Reply