MARYSVILLE – A week-long traffic revision begins Aug. 21 at Highway 9 and 84th Street Northeast as a roundabout is being constructed that is expected to open before Labor Day weekend.

In some cases, detours will add more than 10 miles to a route.

While both directions of Highway 9 will remain open, left turns to 84th will be restricted from 9 p.m. Thursday, Aug. 21, until noon Friday, Aug. 29. Also, drivers on 84th will only be allowed to turn right onto Highway 9.

These revisions will provide crews hired by the state Department of Transportation with the space they need to open the roundabout before the start of school.

WSDOT installs roundabouts to improve the safety of a particular corridor. This intersection was the site of 43 collisions between 2007 and 2012. Roundabouts have been shown to reduce collisions by 75 percent.