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<br />TRAFFIC CIRCLES <br /> <br />DESCRIPTION: As used for traffic calming purposes, traffic circles are relatively small <br />circular or oval median islands (usually landscaped with raised curbs) placed at the center of <br />intersections of local and/or residential collector streets. <br /> <br />APPLICATION: Their primary purpose is to reduce speeds through an intersection or, ifused <br />in a series, reduce speeds for several blocks. They reduce speeds by forcing motorists to <br />negotiate horizontal curves and also by reducing long straight lines of sight on long straight <br />roadways by providing landscaping in the intersection. Traffic circles reduce speeds within 100 <br />to 200 feet of an intersection, and if used between 300 feet and 600 feet apart, can effectively <br />reduce average speeds on a street to below 30 mph, and eliminate all speeds above 40 mph. <br />Circles may reduce traffic volumes based on the traffic circulation and the availability of alternate <br />routes. Depending upon their design, traffic circles can also reduce conflicts at intersections. <br />Caution must be applied when using traffic circle on roadways with more than 6,000 average <br />daily trips. <br /> <br />LIMITATIONS: All traffic calming devices must be approved by the Alameda County Fire <br />Department. Depending upon the design, traffic circles may delay emergency equipment from 6 <br />to 12 seconds. Traffic circles may create conflicts for pedestrians if the vehicle is forced to drive <br />in the path of the pedestrian crosswalk. Vehicles are forced to share the lane with bicyclists since <br />the travel lane is narrow through the intersection. Also, large trucks (Le., moving trucks) may not <br />be able to negotiate left turns around the traffic circle. It may be necessary for these trucks to turn <br />the wrong way around the circle, which is generally acceptable as long as special consideration is <br />taken by the driver. <br /> <br />ADV ANT AGES: <br />. Effective in reducing vehicle speeds <br />. Breaks up sighHine on long straight streets <br />. Opportunity for enhanced landscaping <br /> <br />DISADVANTAGES: <br />. May reduce emergency response time <br />. May impede left turns by large trucks <br />. May pose conflicts for pedestrians and bicyclists <br />. May require removal of on-street parking <br /> <br />TYPICAL COST: Typical construction costs range between $20,000 and $30,000. <br />maintenance cost is approximately $1,800. <br /> <br />I. :: ". I':' <br />. ~~~, / ~;,~ ~."~.. <br />'yP / :-.: 'PJ;:Tn~j,.'.j...~.), '::':' <br /> <br />t(7). <br /> <br />(I ~ rl~' I ';-~ e ('::::e::o::i <br />'-,J'-''' .... <br />~. <br />~ <br />~ <br /> <br />Annual <br /> <br />.. <br /> <br />.. <br /> <br />~ <br /> <br />~ <br /> <br />City of San Leandro, Engineering and Transportation Page 12 of 23 <br />4/20106 NEIGHBORHOOD TRAFFIC CALMING PROGRAM <br />