CITY'S FIRST ROUNDABOUT BEING BUILT; ENGINEERS SAY INTERSECTION SHOULD CONTROL, SLOW TRAFFIC

Ready or not, roundabouts are on their way to Cape Girardeau.

Crews recently started work on the city's first roundabout on Silver Springs Road, and the possibility exists for another at Sprigg Street and Normal and Washington avenues.

But is the roundabout really a necessity for traffic in Cape Girardeau? Will it slow traffic or create accidents? Can drivers maneuver through it?

City engineers hope the extension of Silver Springs Road will help alleviate traffic problems on other roads and that a roundabout can provide a means of slowing traffic -- without adding a signal light -- before it intersects with Route K.

The Silver Springs Road extension project, which will cost nearly $662,000, involves construction of a road from Route K to Independence Street. It is being paid for from the Transportation Trust Fund that voters approved in 1995 to pay for 20 street improvement projects. In August voters will decide whether to extend the existing half-cent tax for five more years.

The Silver Springs project includes the city's first roundabout where the new road meets Gordonville Road. It likely will become the first true roundabout in Southeast Missouri or Southern Illinois.

Cities like Bloomfield, Mo., Chaffee, Mo., Fredericktown, Mo., and Jonesboro, Ill., all have bad examples of roundabouts or what might be better termed a traffic circle, area engineers say. Traffic circles force drivers to stop before entering. Roundabouts allow motorists to yield as they circle a central island.

Certainly roundabouts can cause some alarm for motorists who have never driven in one, but they aren't that intimidating, engineers and designers say.

City Engineer Mark Lester said, "There is a learning curve, yes, but you have that with a four-way stop."

He doesn't expect any more problems with a roundabout than there would be with placing a new four-way stop or signal at the intersection.

"You might have rear-end accidents but you'd have that with a four-way or stop light," he said. "They aren't perfect."

But they might be the perfect solution to road rage or frustrated drivers or even a reduction in accidents.

Roundabouts are supposed to help calm traffic, said Angie Wilson, public affairs manager with the Missouri Department of Transportation in Sikeston. Typically they are green spaces filled with flowers, trees or statues.

"They are much nicer looking" than signals or stop signs," Lester said. "They are virtually maintenance free."

Concrete work is about the same whether you convert an intersection into a roundabout or install a traffic signal, said Lester. With signals there are added maintenance costs, which run about $2,000 a year. Roundabouts are one-time expenses.

Stoplights, which create orderly movements of traffic, also create delays in the traffic flow. Cars might have to wait through a 90-second light cycle to cross a street, which might take six seconds.

And drivers have tendencies to run red lights or stop signs. Roundabouts don't create those problems, Lester said. People run stop signs or lights because they don't want to wait when they are the only car at an intersection. With a roundabout, the drivers would only have to yield to traffic coming into the roundabout.

Roundabouts reduce the number of possible points for accidents from 32 to 8. The number of contact points with pedestrians goes from 24 to 8.

"It's no worse than a four way," Lester said. The only potential problem might be trying to figure out how to make a left-hand turn.

Drivers trying to make a left-hand turn must go three-quarters of the around the roundabout before completing the turn, but traffic islands help guide motorists around the roundabout as they try to maneuver it.

The islands will be angled so that drivers are making a 60-degree turn as they enter the roundabout. That angle will help guide them without forcing them to make a 90-degree turn like they would encounter at a stop sign or light, Lester said.

Roundabouts help keep a better control on traffic by letting motorists move continually through an intersection.

"They increase your capacity by 30 percent," Lester said. That means 30 percent more cars are able to get through the intersection than would move through with a traditional traffic signal.

The roundabout under construction at Silver Springs and Gordonville Road will handle 4,000 cars an hour.

"I doubt we see 4,000 cars per hour even on Mount Auburn," Lester said.

EXTENDING SILVER SPRINGS ROAD

Roundabouts require a yield sign for entering vehicles. Vehicles already in the roundabout pattern have priority over cars just entering the circle. Roundabouts help maintain lower speeds for vehicles moving through and no parking is allowed in the circle. In a roundabout, all vehicles circle a central island.

Traffic circles stop entering vehicles and have areas for conflicted movement. Larger traffic circles provide straight paths for movement at higher speeds and also permit parking within the circle. Larger circles allow room for pedestrian crossing . In smaller circles, left turning vehicles must pass to the left of the central island.

Silver Springs Road extension:

Project cost is $661,450 and includes construction of a roundabout at the intersection of Gordonville Road and signal lights at Route K.

The inner circle of the roundabout measures 40 feet in diameter; an outer circle measures 62 feed in diameter.

The roundabout is being built to handle 4,000 cars per hour.

Source: Missouri Department of Transportation and Cape Girardeau Engineering Department