State engineers call it an innovative design that could save money and speed the flow of traffic along busy intersections.
But Sherri Bennett, an auto parts store clerk who drives the "continuous-flow" intersection built in 2000 in Prince George's County, isn't so enthusiastic.
"It's terrible. It's just very weird," Bennett said of the oddly shaped intersection of Routes 228 and 210, one of only two places in the country making use of the design.
"I would not recommend it," she said.
Road builders are eyeing the plan in other places around the state, including Carroll County, where local officials last week formally signed off on an exploration of the idea for busy Route 140 in Westminster. Supporters say the plan is cheaper than the conventional solution of raising the crossroad on a bridge and building ramps, or cloverleafs, to it.
The system was developed in Mexico. The first continuous- flow intersection in the United States was built on Long Island, N.Y., followed by the one in Prince George's County in 2000.
The design involves building an extra lane for left-turning motorists. Instead of driving to the crossroad and waiting for a green light, these motorists instead cross the highway hundreds of feet before the intersection while oncoming traffic waits at a separate red light. The left-turners then drive to the intersection in a parallel lane and flow into the crossroad with the assistance of another set of synchronized lights that permit oncoming traffic to proceed.
The result: Vehicles make left turns without delaying oncoming traffic. At a conventional intersection, oncoming traffic waits at a red light while left-turning motorists proceed on an arrow.
"What it does do is reduce congestion, which improves safety," said Chuck Gischlar, spokesman for the Maryland State Highway Administration. Continuous-flow intersections reduce waiting time up to 48 percent, he said.
But drivers have resisted the idea. In Howard County a decade ago, planners backed down after an outcry from residents who opposed using the design - then called "dispersed movement" - in Columbia.
"It brings back bad memories just thinking about it," said Charles I. Ecker, who was the Howard County executive at the time and is now head of Carroll County's school system. "Our traffic engineers said it would work. I was willing to try it, but the community was in opposition."
Ed Lieberman, the 75-year old president of KLD Associates, a Long Island firm involved in building the first continuous-flow intersection, is still an advocate.
Lieberman's firm was hired by Howard County to help design the continuous-flow intersection proposal for Route 175 and Snowden River Parkway in Columbia in the mid-1990s.
"I think under certain conditions they can be very cost-effective. For those cases where you have enough land to construct it and where you have a heavy left-turn movement," the intersection can work well, he said.
"It's much less costly and disruptive during the construction process. We have one here on Long Island we designed years ago, and it works fine," Lieberman said. "There's always resistance to change; it's part of the human condition."
James M. Irvin, Howard County's public works director, says the idea would have worked.
"It's just like, at the time, people were against roundabouts," he said. "Like anything, someone has to be the guinea pig on it."
Prince George's County officials said the intersection in their county, built as part of an extension of Route 228, has proven safe and has not resulted in undue complaints. But some residents say they wish the idea had been tested elsewhere.
"I hate that intersection," said Lona Powell, an Accokeek resident and treasurer of the Greater Accokeek Civic Association.
She said she has seen confused motorists traveling the wrong way on the road - into oncoming traffic - as well as accidents. "If you are driving that for the first time, it is very counterintuitive. I think it is by far less safe because I've seen people going the wrong way."
Trudy Gaines, who works at Gaines Electric Co. in Accokeek, said, "A lot of people get confused, make too sharp a left turn and have to put it in reverse to go back into that one single lane to exit."
"It just seems like they could have come up with a better design," she said. "It's not an easy intersection."
Donald Polz, a salesman at Country Carpets, said, "It's a little tricky how you've got to snake over to your exit. You can end up going the wrong way on Route 228. I'd rather have ramps and an overpass kind of thing."
A continuous-flow intersection is scheduled to debut in Louisiana this month, and other states, from California to Florida, are considering the design.
"Based on what I've seen and read, I have no reason to doubt they will work," said Brian Wolshon, who teaches transportation engineering at Louisiana State University in Baton Rouge. "Once people see them more, they should catch on. Nobody wants to be the first to try an innovative or risky approach."
But even though these intersections might safely alleviate congestion, Wolshon acknowledges that they could raise problems, particularly for highway gas stations and restaurants that could be blocked by extended left-turn lanes.
That isn't a problem in Prince George's County because no businesses are on the continuous-flow intersection, according to state officials. And they do not expect trouble on Route 140 in Westminster, where most businesses are in shopping centers, with entrances accessible from cross streets.
Along some crowded highways, "they can be very impactive to businesses like gas stations, when you can only go down the road in one direction," said Kirk G. McClelland, Maryland director of highway development. "You risk cutting off access to these businesses and having to buy them out. That's why these intersections are usually defeated as options."
Montgomery County ditched two proposals for such intersections for that reason, McClelland said.
Yet for the State Highway Administration, continuous-flow patterns remain an attractive vision, consuming less land and money than grade-separated - or cloverleaf - interchanges.
For example, constructing three of these new intersections under the state's improvement plan for Route 140 would run about $100 million to $110 million, according to estimates from the highway administration. Outfitting Route 140 with three overpasses, on the other hand, would cost more than twice that much.
Because the state has yet to allocate funding for the project, wary citizens can still be convinced of the design's efficacy, said Carroll County's planning director, Steven C. Horn.
"There's plenty of time for the state to run animated workshops, showing the public how these work," Horn said.
For more coverage of the proposal and a link to a video of the design: baltimore sun.com/news/local/carroll.