London’s largest roundabout opens Friday with a key difference — it’s the city’s first with multiple lanes of traffic. While no one expects a European Vacation-style horror, with marooned drivers unsure how to get out, the latest twist to the circular intersections could be a challenge for some. Debora Van Brenk puts you in the loop.

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A showpiece roundabout in London could start throwing drivers for a loop by mid-morning Friday.

From the air, surrounded on three sides by cornfields, the city’s newest intersection — at ­Sunningdale and Wonderland roads on its northwestern edge — looks like a giant asphalt crop circle.

The $2.6-million roundabout is one of 25 in the city, and the largest, but the first with multiple lanes, something expected to be a little hairy for the uninitiated.

While it’s a new thing here, such roundabouts are common in Europe and elsewhere in Ontario.

Roundabouts are easier to navigate and safer than traditional intersections with perpendicular streets and traffic lights, says London ­transportation director Edward Soldo.

“Roundabouts have been proven to reduce collisions and in particular, right-angle and head-on collisions,” he said.

Signs and lane markings help direct motorists but the basic rules are simple: Slow down, yield to traffic coming from the left, then turn right into the circle from whatever road you’re on.

Some lanes have been open for weeks but drivers, cyclists and pedestrians can navigate the entire thing sometime Friday morning, said Kevin Welker of Dillon Consulting, which designed the intersection.

Wednesday, contractor L82 was putting the final touches on the site, including landscaping in the splitter islands intended to keep traffic on the right paths.

Soldo is already preparing plans for other multi-lane roundabouts, which he said are ideal at high-traffic areas with plenty of land on the edges of the city.

Initial costs are higher than at traffic light-controlled intersections but operating expenses tend to be lower, Soldo said.

Welker said the social costs of severe collisions sometimes ­suffered at signalized intersections give the advantage to roundabouts.

GETTING YOUR HEAD AROUND A ROUNDABOUT

By the numbers

30 km/h Maximum speed in the new roundabout

60 km/h Speed limit on approaching roads

$2.6M Roundabout’s cost

Straight goods on going round

More efficient traffic flow, virtually eliminates stop-and-go stuff common at regular intersections

Less congestion at high-volume intersections

No idling

Avoid right-angle and head-on crashes

Any collisions are likely to be sideswipes, with less chance of serious injury

Always:

Yield to traffic on the left, pedestrians, cyclists and emergency vehicles.

Be aware of traffic ahead as you approach intersection, to avoid striking other vehicles from behind.

Enter intersection slowly, only when there’s a gap in traffic

Drive slowly toward the right (counter-clockwise), regardless of exit point. Traffic in a roundabout is one-way.

Use signal lights to let others know where you’re heading.

Exit carefully after signalling, yielding to pedestrians and cyclists

Never:

Turn left into a roundabout

Stop in the middle of one

Pass another vehicle in a roundabout

Multilane roundabouts

Stay in right lane if your exit is first road on the right.

Select middle lane if your exit is second or third street on the right.

If you feel stuck in the middle lane, drive until safe to signal, shoulder-check and exit to right.

Cyclists may use either the main road (same instructions as above) or pathway beside roundabout

Pedestrians cross at marked crossings, not through middle of intersection

An expert driver’s view

Roundabouts are great because “they keep traffic flowing, as long as everyone knows what to do,” says Larry Calleja, owner of Ward’s New Drivers of Canada driving school.

Drivers should review the rules of the road if they’re uncertain, and know what the signs mean.

“The biggest problem with the roundabouts is that people don’t realize what a yield (sign) means.

“They think a yield means merge. A yield means, be prepared to stop.”