Last updated on 2023-04-15
Why are traffic circles so great? Flowers!
On Monday morning, a city traffic crew installed a temporary traffic circle — which, unlike roundabouts, can fit inside a typical neighborhood intersection — at 9th Street and Duluth Avenue. Construction included painting some lines and posting some barriers around the painted circle, with arrows directing traffic to the right.
…The residents near 9th and Duluth are most excited. If the city decides in a few weeks to make this a permanent circle, it will allow residents to landscape it with flowers in the middle. [Resident Lura] Roti assured city officials there are plenty of gardeners in the district who can’t wait to spruce up an intersection that droves of drivers and bikers will frequent.
”Once you get inside the Cathedral Historic District, it is just beautiful, and now I think our streets are going to be beautiful, as well,” Roti said [John Gaskins, “Temporary Traffic Circle Near Downtown Sioux Falls May Become a City-Wide Trend,” KSFY, 2023.04.10].
Traffic circles and roundabouts also make it more likely that those flowers will decorate your morning commute rather than your hospital room or early grave:
- Studies of intersections in the United States converted from traffic signals or stop signs to roundabouts have found reductions in injury crashes of 72-80 percent and reductions in all crashes of 35-47 percent (Retting et al., 2001; Eisenman et al., 2004; Rodegerdts et al., 2007).
- A study of 19 higher-speed rural intersections (speed limits of 40 mph or higher) that originally had stop signs on the minor approaches and were converted to roundabouts found a 62 percent reduction in all crashes and an 85 percent reduction in injury crashes (Isebrands & Hallmark, 2012).
- Studies of intersections in Europe and Australia that were converted to roundabouts have reported 25-87 percent reductions in injury crashes and 36-61 percent reductions in all crashes (Rodegerdts et al., 2010).
- Based on the results of a 2004 study (Eisenman et al., 2004), it’s estimated that the conversion of 10 percent of the signalized intersections in the United States to roundabouts would have prevented approximately 51,000 crashes in 2018, including 231 fatal crashes and about 34,000 crashes involving injuries [Insurance Institute for Highway Safety–Highway Loss Data Institute, “Roundabouts,” updated July 2022.].
The traffic circle at 9th and Duluth is already having its desired effect:
Lura Roti certainly thinks so. The University of Sioux Falls journalism professor* has lived in the Cathedral Historic District neighborhood for almost 20 years, and says it is a popular area for motorists who want to avoid stoplights at busy nearby streets. She said they often ignore the stop signs and zoom well above the listed 25 miles-per-hour speed limit.
…“As I’m standing here and cars are going by, they’re already going slower than they typically do, so even though this is a pilot, it’s a pilot that works” [Gaskins, 2023.04.10].
Perhaps counter-intuitively, while traffic circles may reduce speeds, they also reduce delays for drivers and make their roadtrips more efficient:
- A study of three intersections in Kansas, Maryland and Nevada where roundabouts replaced stop signs found that vehicle delays were reduced 13-23 percent and the proportion of vehicles that stopped was reduced 14-37 percent (Retting et al., 2002).
- A study of three locations in New Hampshire, New York and Washington state where roundabouts replaced traffic signals or stop signs found an 89 percent average reduction in vehicle delays and a 56 percent average reduction in vehicle stops (Retting et al., 2006).
- A study of 11 intersections in Kansas found a 65 percent average reduction in delays and a 52 percent average reduction in vehicle stops after roundabouts were installed (Russell et al., 2004).
- An Institute study of two-lane roundabout conversions at two intersections near Bellingham, Washington, found substantial declines in vehicle delays on the minor roads (33 percent and 90 percent) and the proportion of vehicles waiting in queues (35 percent and 43 percent) (Hu et al., 2014). Overall intersections delays increased (12 percent and 22 percent), due to slightly longer delays on the major approaches as vehicles slowed to enter the roundabouts.
Because roundabouts improve the efficiency of traffic flow, they also reduce vehicle emissions and fuel consumption.
Installing roundabouts in place of traffic signals or stop signs has been found to reduce carbon monoxide emissions by 15-45 percent, nitrous oxide emissions by 21-44 percent, carbon dioxide emissions by 23-34 percent and hydrocarbon emissions by 0-40 percent (Hu et al., 2014; Várhelyi, 2002).
Constructing roundabouts in place of traffic signals or stop signs reduced fuel consumption by an estimated 23-34 percent (Hu et al., 2014; Várhelyi, 2002; Höglund & Niittymäki, 1999).
A 2005 Institute study documented missed opportunities to improve traffic flow and safety at 10 urban intersections suitable for roundabouts where either traffic signals were installed or major modifications were made to 10 intersections with signals (Bergh et al., 2005). It was estimated that the use of roundabouts instead of traffic signals at these intersections would have reduced vehicle delays by 62-74 percent.
Based on the results of that study, we estimate that the conversion of 10 percent of the signalized intersections in the United States to roundabouts would have reduced vehicle delays by more than 981 million hours and fuel consumption by more than 654 million gallons in 2018 [IIHS–HLDI, July 2022].
Installing more traffic circles will make your roll through Sioux Falls smoother, safer, and prettier. Let’s round out those intersections!
*Update 2023.04.15 07:10 CDT: KSFY’s Gaskins identifies Lura Roti as a USF journalism prof. Roti informs me that she teaches one writing class for USF’s English department, but her full-time gig is freelance agriculture journalism, with occasional reports for South Dakota Public Broadcasting. She also serves on the Cathedral Historic District Neighborhood Watch Group.
I learned about roundabouts 35 years ago in Europe and Africa. They can be a bit bewildering at first but once one gets used to them they are efficient and time saving. I have to admit that some three-lane roundabouts with the intersection of five roads with traffic lights in heavy traffic in Scotland were a bit challenging (there were also many traffic circles in lesser intersections marked only with paint). In Italy the road signs were about the size of a softball and you might have to go around and around until you figured it out. There is a great roundabout in a once-bad intersection in Spearfish and another by the Billings Airport. Every time I come across one I want to do a fist pump. Thanks for publishing the safety statistics.
Traffic circles are a no-brainer for their benefits. I spent a week in Bend, OR (pop 90k) which has bazillions of roundabouts / traffic circles. (Okay, 42+).
Roundabouts were devised in sixteenth century Europe. Again proving Harry S Truman’s dicta that the only thing new is the history you don’t know.
Roundabouts are all over Europe and I thoroughly enjoyed their benefits during the parts of two decades of living there. The only difference is that the European roundabouts use different yield laws. In Europe, a driver has the right of way to enter the roundabout, but must yield to entering drivers prior to departing the roundabout. Whereas in the US a driver yields prior to entering the roundabout, then has the right of way to depart the roundabout.
If South Dakota had a civil engineering school . . . that creates SD DOT highway and traffic engineers . . . then maybe South Dakota would also have time saving and neighborhood saving roundabouts. One can dream.
https://bendmagazine.com/the-history-and-future-of-bends-roundabouts/
From what I have seen seen hereabouts, the roundabouts are good for the drivers, but if you’re a pedestrian or bicyclist wanting to cross the intersection, you’d better pay attention.
I lived in England for nearly six years. You could always tell when an intersection didn’t have a roundabout …. the traffic was backed up.
Thankfully Billings’s curbing is very shallow on there roundabouts because going through for the first time with a dually and an enormous trailer, I basically bisected the little circle thingy. Oops. Crazy woman driver comin through!
Their*
Billings’? Billings’s? Not sure on that one
Ray Tysdal has a good point….it takes a while to get used to Round-A-Bouts but once you get the hang of it, they are so much safer and faster than stop signs and street lights the choice becomes obvious. In Wisconsin, they also have J intersections where two lanes meet busy four lanes. Those have cut down on some terrible accidents. Give traffic engineers a nod of appreciation. It is just the march of progress.
It took awhile but in Sarasota which went roundabout about awhile back it moves traffic along very well. It’s the older areas with stoplights that have the backup. At least you can adjust the radio. The area around cathedral is old stomping grounds for me, it would add beauty and tons of really awful to very good sculpture. Set up a good jury.
The fellows on bicycles will be confused, as they are apt to be, and some might get run down when they lurch into the traffic. Or, veer off the path and into the flower pots placed in the middle of the road. I suppose since this round-bout is just painted on the street, with flower pots in the middle, some inattentive driver at 2am will just plow straight through from one side to the other and end this experiment.
That South Dakota is too stupid for traffic circles surprises no one.
Grudz, your reality is an experiment in terror.
Indeed, Mr. Anderson.
If you were able to be inside grudznick’s brain it would be like being manacled with some of your heavy metal bracelets to the steering wheel of Mr. Toad’s Wild Ride, over and over again. But there are no traffic circles to really scare you on that ride.