Round and round a road grader goes, sketching a circle in the sand for Woodbury's new traffic roundabout.

It's here, at one of the city's busiest intersections, that an engineering curiosity takes shape for its Wednesday opening. At least 11,000 drivers will navigate the two-lane roundabout at Radio Drive and Bailey Road every day, becoming acquainted with a traffic control device now commonplace in many states but somewhat foreign to Washington County residents.

"It's new right now, but drivers are going to learn how this works," said Transportation Engineer Cory Slagle, who manages the project for the county.

Washington County has one other multilane traffic roundabout location -- state-owned circles in Cottage Grove that opened last month to controversy. Directional signs at Jamaica Avenue and Hwy. 61 confused some drivers into turning left into oncoming traffic instead of right, until the signs were replaced.

Slagle doesn't foresee the same problem at Radio Drive, also known as County Road 13, because the four incoming roads angle to the right into the roundabout. Bailey Road, which runs east and west, is also known as County Road 18.

Roundabouts work on the principle that drivers never stop. Instead, they flow to their right in the circle until they reach the exit that they want. Roundabouts, Slagle said, eliminate traffic backups as drivers wait for lights to change. They also reduce severe crashes that result when vehicles collide in intersections.

Woodbury resident Mary Jane Rohde said she's looking forward to next week's opening because it will end heavy detour traffic behind her house near Radio Drive. The roundabout intrigues her, too.

"I'll have to get down there and try it out, see what we have in Woodbury now," said Rohde, a seven-year resident.

Merlin Bicking, who lives near the roundabout, said many residents aren't happy with a wider highway through their neighborhood. "There's nothing really positive for those of us who live along here," he said. "Just more noise, more traffic."

Radio Drive, which runs from Woodbury south to Cottage Grove, will accommodate at least 20,000 drivers a day 20 years from now. The 1.9 miles of reconstruction, most of it north of the roundabout on Radio Drive, widened the road to four lanes and includes medians and turn lanes. Asphalt trails for pedestrians and cyclists flank the new road. Curbs on the roundabout were poured this week.

Two pedestrian tunnels beneath the roundabout will connect with trails -- linking neighborhoods with the Bielenberg Sports Complex to the south and eventually East Ridge High School, which is under construction nearby. Five rain gardens around the roundabout will collect stormwater runoff.

Even as drivers take their first crack at the roundabout, the construction area won't look finished. That's because landscaping will wait until spring when workers will plant as many as 600 trees and 800 shrubs and bushes along the new road.

Slagle said that full closure of Radio Drive allowed construction to be completed in one season. Construction on Radio Drive, Bailey Road and an improved intersection at Lake Road started on May 29. On the roundabout, it was June 25.

Washington County plans three more traffic roundabouts in Lakeland along County Road 18. Those roundabouts, Slagle said, will offer a safer pedestrian crossing at an elementary school and will reduce crash hazards where several driveways and city streets connect with the highway.

Kevin Giles • 651-298-1554

Kevin Giles • kgiles@startribune.com