ARLINGTON — Construction is set to begin on the intersection of State Route 9 and 172nd Street, south of downtown Arlington, starting June 6.

Drivers should expect traffic shifts, detours and slowdowns for the next several months as the intersection is converted from a traffic signal to a roundabout to help improve safety.

Contractor crews working for the Washington State Department of Transportation will close the east leg of 172nd Street, where it intersects with State Route 9, early on June 6. It will remain closed into July. Drivers will be detoured to 160th Street for access to and from SR 9.

Both directions of SR 9 will remain open during the closure, but the lanes will be narrowed and shifted to the west side of the intersection to help make room for construction of the east half of the roundabout.

The roundabout is expected to open in the fall to help improve safety for the 16,000 drivers using this intersection every day.

Knowing that SR 9 is a heavily-traveled route, WSDOT designed the roundabout to accommodate large trucks, horse trailers and emergency response vehicles.