Circle Gardens of LeConte (& BERKELEY)

Karl Reeh, LeConte Neighborhood Association
Tuesday July 31, 2018 - 10:25:00 AM

The first traffic-calming circles in Berkeley were requested by the LeConte Neighborhood Association in the mid to late 1990s. The main goals were beautification and traffic mitigation on Ellsworth Street. It was our district’s widest street and had NO street trees. After working closely with Traffic and Fire, we designed a circle which allowed the maximum width that the Fire Department would approve with an interior size of 17 feet. A three-foot “collar” of paving blocks added width without further driving restrictions. 

We did not request irrigation due to the significant added costs and increased City responsibility. Instead we agreed to plant, water and maintain each circle with the voluntary help of people living close to the intersections involved. The Park Department agreed to provide and plant trees. 

The neighbors around the first two circles raised $350 to purchase five boulders for Ellsworth/Stuart in memory of five residents who had recently died. Three other boulders were installed at Ellsworth/Parker. After completion of the first two circles, we began the process for getting the third circle built at Ellsworth/Carleton.The next phase began when grants were given to Berkeley for “Safe Routes to School” and “Bicycle Boulevard” plans. This included two traffic lights on Telegraph (at Stuart and Russell.)The Traffic Department mailed out ballots to all households to vote on which, if any, traffic controls would be acceptable. Residents were allowed to vote regarding the intersection that was closest to them. Fulton/Stuart got the highest vote for a permanent circle. 

Both Russell intersections got the next highest votes.Ward (at Fulton and Ellsworth) got the next two highest votes. The minimum number of votes to win a circle was 65 percent. 

In the summer of 2004, all five of the additional traffic circles were completed and volunteers began planting and maintaining the Circle Gardens. These 16to 20 feet wide areas serve as “breathing holes” for the street surface below. With watering and abundant plant life, these small but conspicuous gardens can play a major role in both the quality of life above ground, and the quantity of biological life both above and below. 

Since then about 50 more circles and planting areas have been constructed in Berkeley.  

Circle notes: Marin Circle, the very first in Berkeley, was built in 1911 in a failed attempt to relocate the StateCapitol here.  

Seattle, which has more than 600 of these traffic-calming devices, reports a reduction in accidents of more than 90%. (www.seattle.gov/transportation/docs/JIMM5.pdf.) 

Traffic Circles 

Traffic circles are effective at reducing collisions and the severity at intersections, as well as speeds. Especially when installed in a series, traffic circles also provide an overall traffic calming effect along the entire street corridor. Over the last 30 years, the City of Seattle has installed over 1,000 traffic circles on city streets.

Due to high demand and limited funding, we have developed a process for prioritizing traffic circles. Because the primary purpose of a traffic circle is to reduce collisions at intersections, SDOT evaluates collisions City wide and prioritizes intersections based on the highest number of collisions.. 

Because traffic circles are popular traffic calming devices as well, communities are interested in installing them to calm traffic. Generally, if there are not at least two reported collisions in the intersection for the last three years, SDOT will not support their installation unless there is some other obvious safety need. 

Design & Construction Overview 

Traffic circles are designed according to the existing geometry of the intersection. For example, if each street at the intersection is 25' wide, the diameter of the traffic circle will be 16'.

The traffic circle is made up of a 2' wide concrete ring and reflectors are installed on the ring.. The concrete ring is less than four inches high next to the road so fire trucks or other large vehicles can drive over a portion of the traffic circle without harming the landscaping. There are also reflective object marker signs in the center of the traffic circle so that the traffic circle is more visible at night. For more information on traffic circle design, see Traffic Circle Typical Design

SDOT encourages landscaping in all traffic circles that are of sufficient size to support landscaping. Maintenance of the landscaping is the responsibility of the community, and several volunteers must be identified before the traffic circle is designed and constructed. If there are not enough identified volunteers, SDOT will eliminate the landscaping component from the traffic circle, and pave the interior of the circle instead. 

It generally costs $20,000 to completely construct a traffic circle. SDOT staff designs the circle, and construction is normally completed by SDOT crews. Costs are kept down by not installing irrigation. Water must be brought from nearby residences to help establish the landscaping in the traffic circle.