July 2012 home page

About Roundabouts
Bud Emerson | Klish Way


Fewer conflicts lower the crash potential. The two figures above, from a Michigan State University case study entitled “Converting Old [Intersections] to Modern Roundabouts,” show the conflict points for a typical day. The top figure shows a traditional intersection with 56 [fifty-six] conflict points. The bottom figure shows a roundabout with only 16 conflict points.

Del Mar is in the thick of a widespread trend creating “complete” streets that handle not only cars but pedestrians and bikes. Our Community Plan called out a vision back in the 70’s for a pedestrian-centered downtown, never implemented but now closer than ever in our proposed Village Specific Plan (VSP).
Making a town “walkable” means widening sidewalks, putting in crosswalks, and creating intersections that increase pedestrian safety. Such changes also benefit businesses by bringing them walk-in customers. The most popular feature of complete streets is the roundabout to replace stop signs and stop lights. It is basically a one-way circle that gets drivers to yield before entering. It is usually paired with a “road diet” decreasing four lanes to two. The combination slows traffic to a steady pace instead of stop and start, reduces collisions, and opens up space for bikes and parking. And counter intuitively it increases the average traffic load capacity, which in Del Mar means a reduction of cut-through traffic on neighboring streets.

Del Mar is not alone in this roundabout trend. La Jolla’s Bird Rock neighborhood won two national awards for their new design that slows traffic and has enhanced pedestrian activity and business improvement. Roundabouts work in Encinitas, were approved for Oceanside, installed in Coronado, and five new ones will be central to Leucadia’s 101 traffic plan.

The Village Specific Plan moves us up, what the Brookings Institution calls, a “ladder of walkability,” from least to most walkable. And here’s the unintentional but welcome outcome; it increases property values. We have known for a long time that our rigorous growth controls have been dramatically successful in enhancing real estate values. Walkability has a similar documented effect: “On average, each step up the walkability ladder adds...$82 per square foot to home values,” according to the Brookings study and data.

UT columnist Logan Jenkins sums it up well, commenting on roundabouts in Leucadia’s plan and Bird Rock, “thanks in large part to the roundabouts in the main drag, Bird Rock is prettier, safer and more prosperous. The fancy coffee is flowing; pedestrians and bicyclists feel at home; and the merchants have a renewed lease on life.”

According to the Insurance Institute for Highway Safety, modern roundabouts reduce motor vehicle crashes. Their July 2001 Status Report noted “most serious kinds of crashes at conventional intersections are virtually eliminated by roundabouts…Crashes that do occur tend to be minor because traffic speeds are slower.”

The figures on the left from a Michigan State University case study entitled “Converting [Intersections] to Modern Roundabouts” show the relationship between the speed of the vehicle and the likelihood of death to a pedestrian if hit by a vehicle travelling at that speed.


© 2007-2015 Del Mar Community Alliance, Inc.  All rights reserved.