- November 21, 2024
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It turns out roundabouts are a source of great passion. Plans to put a string of them along U.S. 41 have inflamed those passions. If you’ve been to any of the public events about them in the past few years, you know what I mean. Cries of “They are proven safer” and “They will improve traffic flow” battle against screams of “Don’t you know how old the population of Sarasota is?” and “No one here knows how to drive in a roundabout.”
Many locals say Sarasota is not like most other places in demographics, travel patterns and the fluctuating volume of out-of-town drivers. Many feel like state and local officials are gambling locals’ mobility on foreign and complicated new intersections.
I’ve worked in transportation for more than 25 years, so I thought walking through some pros and cons and examining what we do and don’t know would be helpful.
According to the Federal Highway Administration, “The United States now has nearly 4,500 modern roundabouts, meaning the number has nearly doubled over the past 10 years.” One national study of roundabout trends found about 1,300 of them in Florida, more than any other state in the nation. The accompanying diagram shows the basics of what a roundabout looks like and how it operates.
In a roundabout, all vehicles are going the same direction, so head-on collisions are extremely rare. They make U-turns safe and easy, they rely much less on the correct use of turn signals for drivers to know where others are going, they make rear-end collisions less likely because nobody has to stop within the roundabout, and they eliminate left turns across traffic — you know that game of chicken trying to find a big enough gap in the opposing flow to dash across. (Especially when some giant SUV is blocking your view, grrrr.)
However, if you drive through the roundabouts on Ringling Boulevard, Main Street, at Bradenton and Myrtle, Southgate Circle or St. Armand’s Circle, you know there are people who don’t yield when they should, who stop rather than entering the circle when they should and who cut across lanes or don’t signal when they leave the circle. When a driver in a roundabout is not paying attention or is confused or clueless, you don’t want to be behind them or in their way.
But everything in that last sentence is also true for a regular intersection.
The statistics are pretty telling. FHWA says that roundabouts reduce accidents by about 50% and more importantly, reduce accidents with serious injuries or fatalities by about 80%. I looked at detailed case studies in Minnesota and Maryland where roundabouts reduced all accidents in those intersections by 50-70% and eliminated fatal accidents completely. FDOT says that roundabouts in Florida have resulted in 90% fewer fatal crashes, 75% fewer injuries in those and 10-40% fewer pedestrian/bicycle crashes, and they are safer for beginner and elderly drivers.
Sarasota wants to increase the number of people walking and cycling. The FDOT numbers say roundabouts are safer for pedestrians and cyclists, but do they discourage them anyway? Pedestrian crosswalks need to be set far enough back from the entrance to roundabouts, so drivers are not dealing with them at the same time they are focused on how to enter the circle. Cyclists can dismount and use the crosswalks of course, but they can also ride through following the same rules as cars. The problem is that in side-by-side flow with cars, where people merge right to leave the circle, it is very hard for cyclists to stay out of the blind spot of cars. Even more so because drivers in roundabouts tend to focus on figuring out what all the cars are doing and can easily forget to look for cyclists.
The key for many cities has been to really invest in careful design and placement of warning signs and guidance signs around the circle about pedestrian crossings and watching for cyclists. Awareness is the key.
As I listed above, Sarasota already has a fair number of roundabouts, which have not been overly controversial. But many are concerned that the new ones on the heavily travelled U.S. 41 will make congestion on this vital arterial even worse. Normally roundabouts improve flow because people don’t usually have to stop, just slow down, to enter. In technical terms roundabouts have 30-50% higher flow capacity than conventional intersections. And because I seemingly never catch two green lights in a row on U.S. 41, that makes sense to me. But if traffic is heavy enough, that slowing down might cause backups that slow down the overall rate of travel along the corridor. This can be a real problem for emergency vehicles during high-traffic times. Overall, research shows that roundabouts don’t have a large effect on congestion, positive or negative, relative to overall factors like the capacity of the corridor relative to the amount of traffic trying to use it.
Roundabouts can consume more land than conventional intersections, depending on the width of the road, which can be costly in an expensive urban area. However, maintenance and operating costs for roundabouts are a fraction of those for conventional intersections. They also don’t need police to direct traffic during power outages and emergencies. Roundabouts also reduce pollution because they reduce starting and stopping, which creates much higher emissions from cars than continuing to roll along.
Roundabouts are unfamiliar for many drivers, and that causes many of the problems that do come with them. Many state and local governments in the U.S. that have built new roundabouts have pioneered extensive programs of outreach and public education to make it as easy as possible for people to learn about them before they find themselves driving through them. And, of course, the more a person drives through one, the easier it becomes. Sarasota can learn from and even copy many of these programs, aiming at residents of all types, maybe with extra emphasis on older drivers and on tourists.
Dr. Adrian Moore is vice president of Reason Foundation and lives in Sarasota.
