They are a contentious subject in the USA, with vocal opponents and supporters on either side of the debate. Join us as we consider whether for a safer, more efficient, and sustainable approach to traffic management at intersections, it’s about time for more roundabouts.
A Brief History
Although modern roundabouts didn’t start appearing in the United States until the 1990s, their history can be traced back to European circular junctions developed in the mid-18th century. Famous examples include the Circus, in Bath, England, and the Place de L’Etoile surrounding the Arc de Triomphe in Paris.
Though these early traffic circles share the same basic structure – traffic moves in one direction around a circle – they differ substantially from modern roundabouts in both design and the rules that govern them. The biggest issue with these early circular junctions was that traffic inside the circle was required to yield to vehicles entering the circle, disturbing the flow of traffic through the intersection.
It was not until the beginning of the 20th century that they really took off. While early versions were large traffic circles with multiple lanes, smaller traffic circles like the one built in 1909 in Letchworth Garden City in Hertfordshire, UK made maneuvering the intersection much easier. The first modern roundabouts were popularized in the 1960s when the United Kingdom instituted the first “yield-at-entry” rules and other innovations designed to slow vehicle entry speed, deter left turns, and improve visibility.
Those fundamental changes kicked off a wave of development and experimentation (with varying degrees of success) mostly throughout Europe. The world’s wackiest example must be Swindon’s Magic Gyratory in the UK. It’s comprised of 5 minicircles built to form one large central circle where traffic can flow either clockwise or counterclockwise. But the Brits love it so much it even has its very own appreciation society!
The Pros and Cons
The whole point is to manage traffic at intersections in a safe and efficient way. Numerous studies have shown them to improve traffic flows and to be far safer than conventional junctions controlled with stoplights. They are also far better suited to handling intersections with more than four approaches and incorporating minor approaches. Their service life is also much longer – about 25 years against 10 years for an average traffic signal.
They do have their disadvantages, though. Building and maintenance costs can be higher than traditional crossroads, and the larger land requirements have both a financial and environmental impact. When traffic is congested, there are a lot more cars close together which increases the chance of low-speed fender benders. And they are probably not the ideal solution in situations where traffic flows are unbalanced.
The Case for More
Many arguments that they are unsafe simply come down to drivers’ unfamiliarity with the concept. There are fewer than 8,000 throughout the US compared to almost 30,000 in the UK. Encountered on a daily basis, safely navigating one becomes as easy as obeying a red light or a stop sign. Although the previously mentioned Magic Gyratory was voted one of the scariest road junctions in the UK by the BBC, they also concluded that it had an excellent safety record and had resulted in a large fall in the number of crashes.
This point is echoed by evidence that shows accidents are generally sideswipes rather than head-on collisions. While it is easy to blow through a red light, traffic circles aren’t as easy to drive around quickly. In fact, research by the National Cooperative Highway Research Program in the US found that they led to a 35% fall in crashes. More significantly, fatalities were down by a staggering 76%.
There are valid arguments that they can create an unsafe environment for pedestrians and cyclists. There’s no doubt that early versions were designed almost exclusively with vehicles in mind. But just as the safety features of automobiles have improved dramatically, so too has roundabout construction. Simple innovations such as sidewalk separation, setting crosswalks back, improved markings, and ramps for cyclists can make a huge difference in safety outcomes.
Increasingly environmental concerns are taking a front seat in decision-making around transportation. Research has shown that traffic circles can promote fuel savings of up to 40% due to traffic flowing more freely. A study by the Insurance Institute for Highway Safety estimated that a 10% conversion of conventional junctions would have reduced delays by 981 million hours, resulting in the saving of more than 650 million gallons of gas.
With so much in their favor, there is a growing feeling across the nation that it’s about time for more. A great example is the Nevada Strategic Highway Safety Plan which promotes traffic circles being considered before any other form of traffic control. While the U.S. may be a little behind on the roundabout trend, there’s a good chance we’ll be catching up soon!