The massive, year-long “H-1 Rehabilitation” project got underway tonight with a complete shutdown of the highway’s eastbound lanes from Likelike Highway to Ward Avenue.

The closure was in effect from 8 p.m. to 4 a.m. Monday.

An hour into the first closure tonight, eastbound traffic heading toward the closure was light and there was little congestion on the final offramp before the barricades.

Traffic along surface streets in the Kalihi and downtown areas was also relatively light.

The same stretch of highway will be closed again from 8 tonight to 4 a.m. Tuesday.

The much-needed, much-dreaded Department of Transportation project calls for the repair and repavement of the 3.5-mile corridor between Middle Street and Ward Avenue, an expanse of heavily traveled highway that has not been repaved in 15 years.

In hopes that heightened public awareness would minimize the difficulty drivers may expect over the coming year, the DOT worked with hospitals, private businesses and community groups to spread the word about the project.

“We know that people won’t necessarily be happy about it, but we they will be understanding of the need for it,” DOT spokeswoman Caroline Sluyter said today.

Sluyter said scheduled complete overnight shutdowns — including the two this week plus 120 next year — will allow road crews to complete the work as quickly as possible.

On most work weeks, Sunday through Thursday, crews will close one lane in each direction starting at 9 p.m., then close an additional lane at 11 p.m. This will leave one available lane in each direction. The lanes will reopen at 4 a.m.

Sluyter said the lane closures will likely result in “significant delays” of up to 20 to 30 minutes in drive time.

The department is advising southbound motorists coming from Red Hill and Moanalua to take the Airport viaduct to avoid slowdowns on the freeway.

Sluyter said Hawaii drivers have proved resilient and adaptable during previous major projects.

“The first few nights may be bad, but it should get better as people find alternate routes and adjust their schedules,” she said.