CAMDENTON, Mo. (AP) -- Hurry up and slow down. Everyone who has ever driven a busy two-lane road knows this frustration: You wait miles for a break in oncoming traffic to pass a slower vehicle, only to get slowed down again by another caravan of cars and trucks.

Some two-lane roads have occasional passing lanes, for example when heading up a big hill. But short of four-laning every road, there's only so much the state highway department has been able to do.

Until now.

The Missouri Highways and Transportation Commission on Wednesday is expected to approve what apparently will be a model project nationally -- a hybrid of normal two-lane and four-lane roads in which a passing lane will alternate every mile or so between the north and south lanes.

The $50 million experiment is planned for a 16-mile stretch of Missouri 5 between Lebanon and Camdenton, a twisting and sometimes slender two-lane road that connects Interstate 44 to the Lake of the Ozarks.

The concept of a continuously alternating passing lane has been used for years in parts of Europe, which is where Missouri's chief highway engineer came up with the idea. But it's so new in the United States that transportation officials haven't even agreed on what to call it.

The Missouri Department of Transportation described it as "continuous three-lane passing" or an "alternate four-lane" road when developing the project. Now the department markets it as a "Shared Four-Lane Highway." The American Association of State Highway and Transportation Officials calls it a "2+1" road.

Jim McDonnell, AASHTO's deputy program director for engineering, said the Missouri project is believed to be the first one getting under way in the U.S.

Several years ago, the association helped arrange a European road tour for various American transportation officials. A report from the trip concluded that "2+1" roads there were effective in rural areas at addressing both safety problems and traffic congestion.

"You get almost the same traffic volume and safety benefits of a four-lane highway. That's the theory," said Kevin Keith, MODOT's chief engineer.

On any given summer weekend, Missouri 5 is packed with pickup trucks pulling boats and personal watercraft, recreational vehicles and the typical mixture of cars, sport utility vehicles and tractor-trailer rigs -- many making their way to or from the mid-Missouri lake that local officials claim attracts 5 million visitors a year.

The highway averages 8,000 vehicles a day -- enough to justify a four-lane road under MODOT's historical benchmarks, Keith said. In fact, a four-lane road was promised as part of the state's 15-year road plan adopted in 1992, but it never was built because the state lacked the money.

The alternating passing lanes can be built at half the cost of a four-lane divided highway, Keith said. Construction is scheduled to begin by next summer and be completed by mid-2010. The southern portion of the project will widen the existing two-lane road; the northern portion will follow a new route, eventually connecting to a new four-lane bypass around Camdenton.

While the current road curves just to the east of the rural Decaturville One Stop, the new road will pass just to the west. Some hope it will be a lifesaving change.

In the eight years she has owned the convenience store, RandyJane Hunt-Reed says her video surveillance cameras have captured dozens of accidents in the background. A green Honda Civic, its front end scrunched in, has sat on her parking lot for about a month after being immobilized by a crash. A few months before that, another vehicle crashed into a telephone pole while swerving out of the way of an oncoming passing car.

The problem is the same almost every time: "There's no passing areas, and when they try to pass, they can't see, and they don't use good sense," Hunt-Reed said.

Those who travel the road frequently often have tales of close calls and frustrating delays.

Bev Thomas, a Camden County commissioner who serves on a regional transportation planning panel, believes the crowded road discourages some tourists from coming to the Lake of the Ozarks. The regional panel recently ranked an improved Missouri 5 as the area's No. 1 transportation need, she said.

The project is being added to Missouri's $5 billion, five-year highway plan thanks to an influx of money from a 2004 constitutional amendment, which authorized bonds backed by the redirection of existing state taxes and fees to roads and bridges. That revenue spike is about to plummet, as the state pays off those bonds.

As a result, the Missouri 5 project is the only "Shared Four-Lane Highway" in the department's plans. But if it works well, it could serve as a model for the future, Keith said.

"The goal is to get one built, get it in place," Keith said. "We don't know how Missouri drivers will react to it."

On the Net:

MODOT: http://www.modot.mo.gov

AASHTO: http://www.transportation.org

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