By Karl Kim
The French love them. Thousands of them have sprung up in Seattles neighborhoods.
Theyre showing up in places as diverse as Florida, Colorado, Massachusetts and Makiki.
Roundabouts, like the one at Keeaumoku and Heulu streets, are taking the nation by storm. And the Islands as well: in Salt Lake, near the entrace to Ford Island, and dozens in the works for streets all over Honolulu.
What is it with all these roundabouts, anyway?
Roundabouts are one of the most effective and visible tools employed by urban planners, traffic engineers, landscape architects, and others interested in improving safety, efficiency, mobility, access, and aesthetics for roadway users.
Note that I have used the term "roadway users" to include not just motorists, but also pedestrians, bicyclists, persons with disabilities, and others who share space that single-occupant vehicles typically dominate.
Roundabouts are key devices for "traffic calming" - the engineering, enforcement and educational strategies designed to reduce vehicle speeds; promote safety for pedestrians, bicyclists and non-motorized travel modes; and enhance the overall quality of life in our urban neighborhoods.
A "calmed" street encourages more walking and better social interactions. Traffic calming can promote a stronger "sense of place" and reduce the externalities (noise, dust, pollution, etc.) associated with high-speed traffic. It also can help stimulate investment in a community, not to mention making it a more desirable place to live and work.
When traffic in a community increases, planners typically install stop signs, first on cross-streets, and then at all four-way intersections. Eventually, as traffic builds, pressure to install traffic lights increases.
As more of the four-way stops are converted to signalized intersections, there is increased need for time-of-day signal control, computerized signaling, pavement loop detectors, video cameras and other infrastructure for managing traffic flows.
Yet one of the basic problems of a four-way intersection with either stop signs or traffic signals is that people still manage to run the stop sign or the red light.
An elegant solution
The roundabout provides a simple yet elegant solution for eliminating most broadside and head-on crashes. A properly designed roundabout, with splitter islands, will reduce the speed of all vehicles entering an intersection. It also will reduce the number of "traffic conflicts" between vehicles in the intersection.
A traffic conflict is a potential crash between two vehicles or between a vehicle and pedestrian.
A typical intersection contains 32 potential places where vehicles can crash. However, intersections with roundabouts, have only eight such hazardous spots.
Roundabouts also increase the safety for pedestrians by reducing the number of places in which they can be struck.
Learning to look left, yield
One problem that has arisen in Hawaii is that some do not understand how to enter a roundabout. The rules are fairly simple: Since priority is given to vehicles within the roundabout and, in Hawaii, roundabouts only have one direction of travel (counterclockwise), the rule of thumb is to look left and yield to oncoming traffic.
In observing roundabout behavior in Hawaii, I have noticed that many of those within the roundabout are yielding to those entering the roundabout. I also have noticed that many of those in the approach lanes have cut in front of those already within the roundabout. This is in spite of the posted yield signs on each of the approach lanes.
Instead of the televised public service announcements that said, "in, around, and out," it might have been more instructive to remind drivers, to "look left, and yield to on-coming traffic."
Before the traffic light
Roundabouts, as a concept, are not exactly new. Town squares or circles with a statue or fountain (like the one at the base of Kalakaua Avenue, across from Kapiolani Park) were quite popular even before the advent of the automobile.
Eugene Henard, who was architect for the city of Paris at the turn of the century, was one of the first to introduce the concept of a center island surrounded by traffic moving in the same direction as a method of intersection control. During the same period, William Phelps Eno, also known as the "father of traffic control," was proposing roundabouts for New York City.
But as traffic volumes increased, the roundabout gave way to signalization. Soon, the simplicity and functionality of roundabouts were forgotten in favor of more "modern" approaches that made use of electricity, stop lights and, eventually, synchronized traffic control.
Cities throughout the United States are not only building roundabouts but also working to improve their designs. The University of Hawaiis Department of Urban and Regional Planning last year was host to a well-attended workshop on roundabout design.
Why have they become so popular?
First, roundabouts have clear safety benefits. They eliminate one of the most hazardous turning movements, that of the left turn into oncoming traffic.
European countries have taken the lead in terms of the evaluation of the safety of roundabouts. One widely cited study found a 41 percent reduction in overall accidents and a 71 percent decrease in the number of casualties following installation of roundabouts. Similar encouraging results have been reported in U.S. and Canadian studies.
A second benefit is increased roadway efficiency. There is often a great deal of unnecessary delay associated with stop lights or stop signs. How many times have you been stopped at a red light when there is no other traffic near the intersection? This unnecessary delay can be compounded if there is a queue of vehicles stuck at a red light. Although roundabouts slow traffic down, they also allow for continual movement. Thus, the actual flow through capacity and efficiency of an intersection may be better.
A third benefit is cost. Roundabouts are relatively simple to design, and unlike a traffic signal that requires electrical wiring and ongoing maintenance, a roundabout is much cheaper to build and to maintain.
Mainland cities are building and installing roundabouts for about $16,000. Many cities have worked out arrangements with community organizations or neighborhood groups to maintain their roundabouts.
Finally, the roundabout is an "equal opportunity" traffic control device. Unlike priority signalization, which may give preference to motorists on trunk lines or main roads, the roundabout gives priority to whoever enters the intersection first.
A pleasing, calmer life
The City and County of Honolulu, under Mayor Jeremy Harris and transportation chief Cheryl Soon, not only have embraced roundabouts, but also have launched a strong traffic calming program in the name of improving neighborhoods qualities of life.
Involving national known experts in the field, such Dan Burden of Walkable Communities, or nationally known roundabout design Michael Wallwork, the city also has worked hard to bring traffic calming into the neighborhoods.
Working together, residents, city officials, and professionals can not only solve transportation problems, but also can plan and build better communities.
Karl Kim, Ph.D., is professor and chair of the Department of Urban and Regional Planning at the University of Hawaii at Manoa.
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