When drivers prepare to enter or exit Interstate 69 at the new Union Chapel interchange late this summer, theyre in for a surprise. Instead of the cloverleaf configuration theyre used to, theyll find roundabouts in both directions. The new feature wont be a pleasant surprise for some, but the advantages of roundabouts make it worthwhile to grow accustomed to them.
In safety, traffic flow, environmental concerns and cost, roundabouts are the path forward on Hoosier roads and highways. The state has about 100 roundabouts now, according to Toni Mayo, spokeswoman for the Fort Wayne district of the Indiana Department of Transportation, but the figure is expected to increase by 40 percent over the next decade.
What they are
The nations first traffic circle was New York Citys Columbus Circle, built in 1905. It was designed by William Phelps Eno, known among traffic engineers as the father of traffic safety. However, the circles that followed his first design were anything but safe because they allowed right of way to motorists entering the circle.
High crash experience and congestion in the circles led to rotaries falling out of favor in America after the mid-1950s, according to a Federal Highway Administration publication on roundabouts. Internationally, the experience with traffic circles was equally negative, with many countries experiencing circles that locked up as traffic volumes increased.
But the United Kingdom improved on a generally sound idea when it adopted a mandatory give-way rule at traffic circles, requiring entering traffic to yield to circling traffic. The simple change prevented gridlock.
Another tweak was in the design: Smaller circles required drivers to enter and circle more slowly. The two changes reduced both the number and severity of collisions, leading to roundabout intersections as a common traffic design in many countries.
An inventory of modern roundabouts compiled by an engineering firm in Portland, Ore., lists just fewer than 1,700 in the U.S.
Why they’re better
Drivers unaccustomed to roundabouts might be wary, but the traffic design is actually much safer than a traditional intersection. T-bone, left-turn and head-on collisions are eliminated. Crash severity is lower because roundabouts require reduced speed.
A 2001 study by the Insurance Institute for Highway Safety found that converting intersections from traffic signals or stop signs to roundabouts reduced crashes involving injuries by 80 percent and all crashes by 40 percent. A 2008 study by an Iowa State University researcher of 17 rural intersections with speed limits of 40 mph found that the average injury crash rate was reduced by 84 percent and fatal crashes were eliminated when the intersections were converted to roundabouts.
Roundabouts improve the efficiency of traffic flow because cars arent needlessly stacked up at red lights. The efficiency results in reduced fuel waste and vehicle emissions. An Insurance Institute study found that for 10 intersections in Virginia, fuel savings amounted to 200,000 gallons annually.
The design also addresses issues affecting older drivers, who are disproportionately involved in crashes at intersections.
Older drivers intersection crashes often are due to their failure to yield the right of way, according to the Insurance Institute. Particular problems for older drivers at traditional intersections include left turns and entering busy thoroughfares from cross streets. Roundabouts eliminate these situations entirely. A 2007 study in six communities where roundabouts replaced traditional intersections found that about two-thirds of drivers 65 and older supported the roundabouts.
INDOTs Mayo said that the cost of acquiring land for roundabouts is comparable to that of a compact diamond interchange. But construction costs for the diamond configuration are slightly higher because it requires a larger bridge and more pavement.
There are no signals needed at roundabouts – just signage, she said. That can reduce maintenance costs.
Parkview Health picked up $10 million of the total $13.9 million Union Chapel interchange project. It will allow access to Parkviews new hospital from the north and also relieve congestion on Dupont Road.
The roundabouts on Union Chapel are the first in the area linked to an interstate but certainly not the first to be built here.
If drivers are wary of roundabouts, their concern might be based on experience with the tight traffic circle at Coventry Lane, on the citys southwest side. It was designed to handle only neighborhood traffic. But there are others across Allen County operating efficiently. A roundabout on the IPFW campus eases traffic flow near Walb Union and an adjacent parking garage.
The citys public works director, Bob Kennedy, said officials havent heard any recent complaints about its roundabouts and even suggested that neighborhood residents would be outraged if the city replaced the roundabout at Old Mill and Westover roads, which was added to slow traffic. Dual roundabouts replaced a spaghetti-bowl collection of ramps at Pontiac and Wayne Trace almost a decade ago, in a configuration similar to the new Union Chapel interchange. Further southeast on Wayne Trace, a roundabout tames an intersection of Adams Center and Marion Center roads.
Angola drivers, of course, have long been accustomed to the circle downtown surrounding a Civil War monument at U.S. 20 and Indiana 127.
As part of a project that would restore Ewing and Fairfield to two-way traffic, Fort Wayne traffic officials are considering a roundabout where those streets intersect with Superior and Wells.
Shan Gunawardena, city traffic engineer, said a roundabout would address the awkward five-legged intersection created by the change. Another roundabout is under consideration at the intersection of Maysville, Landin and Trier roads.
From an operation standpoint, they make a lot of friends assuming they are designed right, Gunawardena said.
They certainly have in Marion County, where the city of Carmel eliminated 80 percent of its traffic lights by constructing 60 roundabouts – and attracted the 2011 National Roundabout Conference.
When the new Union Chapel interchange opens at the end of this summer, inevitably there will be some grumbling and confusion. But as roundabouts become more common, look for drivers to become more comfortable and more aware of the advantages they offer.