Monday a southbound lane will close on Fairview Avenue North for about a week, and in August, more severe lane closures will occur south of Mercer.

After five months of relatively normal travel through the Mercer Street construction zone, the nearby roads are about to tighten.

On Monday, a southbound lane will close on Fairview Avenue North just north of Mercer for about a week so utility crews can install a new water main.

Then in August, a more severe set of lane closures will occur south of Mercer, where traffic flows downhill in the afternoon, toward entrances to both directions of Interstate 5 as well as its northbound express lanes.

When the project began in late January, project manager Angela Brady of the Seattle Department of Transportation rejiggered the schedule with contractor Gary Merlino Construction, to postpone the pain on Fairview as long as possible. Since then, traffic on Mercer itself has moved at a fairly normal pace, as cars from Amazon’s new office garages filled the side streets, requiring traffic police.

During next week’s utility work, on Fairview between Aloha Street and Valley Street, one southbound lane and one northbound lane will stay open at all times, and entrances will be kept open to restaurants and other businesses at Chandler’s Cove along Lake Union.

There also will be three weeks of related overnight closures on Fairview Avenue North at Valley Street, starting Monday, when one lane from I-5 to northbound Fairview will close at night.

The $164 million project will convert eastbound Mercer to a two-way boulevard with a planted median and wide sidewalks by the end of this year. Valley Street is to be rebuilt in 2013 as a two-lane street with bicycle lanes next year. The city then plans to rebuild Mercer to the west, including a widening of the Mercer underpass at Aurora Avenue North.

Mike Lindblom: 206-515-5631 or mlindblom@seattletimes.com. On Twitter @mikelindblom.