State Highway 20 south of Coupeville will be reduced to one lane on Monday, Jan. 11, from 9 a.m. to 4 p.m., the state Department of Transportation said.

The closure will let Puget Sound Energy install utility poles in preparation for that agency’s $5.8 million SR 20 safety-improvement project, it said.

That project will reroute Parker Road to connect to Morris Road, close the SR 20 intersections at Parker Road and at Smith Prairie Road and add turn lanes at Morris Road and the near the county transfer station.

Work on the improvements is slated to begin this summer.