Roundabouts: A Way Around Costly Accidents’

By | August 14, 2000

The Insurance Industry’s Increased Interest in Auto Safety Has Produced Research that Provides Compelling Reasons to Send Our Traffic in Circles

Each year in the United States more than 800 people die and an estimated 200,000-plus are injured in crashes that involve running a red light. Legislators and insurers are near the top of the list of those interested in finding a way around these costly and deadly accidents. And for good reason. One possible solution gaining more and more attention is the century-old concept of the roundabout.

They may be an unfamiliar type of intersection to the United States, but as evidence of their benefits grows, roundabouts are popping up in neighborhoods and on major thoroughfares throughout the country. In Texas, which boasts three of the top ten deadliest intersections in the country, according to a recent State Farm Insurance Co. report, that could be very good news. And not just for motorists, but for auto insurers whose profits have been affected by increasing claims costs over the last several years.

Researchers at Ryerson Polytechnic University, the Insurance Institute for Highway Safety and the University of Maine studied crashes and injuries at 24 intersections before and after construction of roundabouts. The study found a 39 percent overall decrease in crashes and a 76 percent decrease in injury-producing crashes. Collisions causing fatal or incapacitating injuries fell as much as 90 percent at some intersections.

According to the IIHS, these findings are consistent with those from other countries where roundabouts have been used extensively for decades. And the safety benefits do not hamper traffic flow. In fact, the study found that where roundabouts replace intersections with stop signs or traffic signals, delays in traffic can be reduced by as much as 75 percent.

The resulting safety could be affected, in part, by motorists’ counter-intuitiveness according to researchers. The intersection could appear more difficult to maneuver and therefore, drivers are automatically more cautious.

“Given the magnitude of these crash reductions, there’s no doubt that roundabouts are an important countermeasure for many intersection safety problems,” said Brian O’Neil, IIHS president. “Replacing signals or stop signs with roundabouts will reduce the number of crashes and save lives while at the same time improving traffic flow.”

The study suggests that roundabouts benefit from good geometry, exhibiting only a fraction of the troublesome crash patterns typical of right-angle intersections. Such intersections “place vehicles on a high-speed collision course, with crashes avoided only if drivers obey traffic laws and use good judgment. Research shows many drivers don’t, so the potential is high for right-angle, left-turn and rear-end conflicts,” according to Richard Retting, IIHS senior traffic engineer and an author of the study.

The roundabout’s lack of right angles, combined with reductions in speed make the intersections safer for pedestrians and bicyclists as well as people in cars. The speed depends on the intersection, but generally remains at about 15 mph. At that speed, drivers and others on the road have more time to react, so there’s a smaller chance of collision. And when crashes do happen, they are usually minor.

On The Greener Side
Roundabouts also have environmental and aesthetic appeal. Roundabouts cut vehicle emissions and fuel consumption by reducing the time drivers sit idling at intersections. Traffic that moves more slowly through intersections creates less noise and congestion, minimizing the expressway look and feel of roads in urban and suburban areas. And landscaping on the island at the center of a roundabout offers visual appeal and restores a bit of nature. Roundabouts also create visual gateways to communities or neighborhoods, and in commercial areas they can improve access to adjacent properties.

“Roundabout construction should be strongly promoted as an effective safety treatment at intersections,” Retting said. “There’s nothing to lose from constructing them and everything to gain. The proof is already there.”

The Eyes of Texas Are Upon You
Texas legislators will very likely address intersection safety during the 2001 legislative session. At the top of the intersection safety list could be the installation of cameras at red lights.

Nationwide, fatal crashes at traffic signals increased 18 percent during 1992-98, more than three times the rate of increase for all other fatal crashes during the same time. These figures, compiled by IIHS, also show that red-light running is a major factor in the problem. Cameras won’t make the intersections safer, but they could act as a deterrent for red light runners. The cameras, already in use in about 40 U.S. communities, including Dallas, Houston and Austin, photograph vehicles whose drivers deliberately run red lights. Violators are then ticketed by mail. IIHS estimates the programs reduce red light running by about 40 percent.

But there is a down side. The cameras cost money to install and maintain. Roundabouts, however, are less expensive than intersections controlled by traffic signals, saving up to $5,000 per year per intersection in electricity and maintenance, not to mention the installation of cameras.

Comin’ ‘Round Again
Rotary intersections may seem like a novel new idea, but they predate the automobile. In 1905, the first U.S. traffic circle, then known as a gyratory, was constructed in New York City, and European countries built them in great numbers through the early part of this century.

In its basic form, a traffic circle consists of a raised island at the center of an ordinary right-angle intersection. The island, which directs cars counterclockwise, is intended to reduce speeds, although this goal isn’t always achieved. Other configurations can be more complex. They may involve split lanes and combinations of yield signs, stop signs and traffic lights—all of which can be confusing to drivers trying to negotiate them.

But the modern roundabout improves on such designs. This is an important distinction according to IIHS, because the older traffic circles aren’t always easy to navigate, so they haven’t been very popular. Anyone who has driven The Circle in Waco can attest to that.

“At modern roundabouts, triangular islands at each entrance slow approaching vehicles,” said Richard Retting. “In older traffic circles, no physical structures prevent drivers from speeding right into the intersection. This lack of control contributes to high-speed conflicts inside the circle.”

Faster, Faster, Faster
Roundabouts have not been popular in U.S. engineering because slowing down is a seeming inconvenience to drivers, according to IIHS. And American universities and institutions that influence road planning and engineering have reinforced the historical practice of building high-speed intersections.

“The priority for road planners and engineers in this country has been to process as much traffic as possible. Traffic signals have become the technology of choice,” Brian O’Neil said. “It’s hard to deviate from that approach. Countries in Europe and elsewhere have been much more progressive in focusing on traffic calming and making intersections safe for pedestrians. They caught on long ago to something we’ve ignored because of our fascination with technology. Recent interest in roundabouts in the United States is one sign that priorities finally are shifting.”

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