The repair work on northbound Interstate 5 in Seattle is five days ahead of schedule and could be done by next Saturday morning. A combination of dry...

The repair work on northbound Interstate 5 in Seattle is five days ahead of schedule and could be done by next Saturday morning.

A combination of dry weather, fast-setting pavement and increased manpower has helped the contractor, Concrete Barrier of Mukilteo, to accelerate the job, said Matthew Preedy, a project engineer for the state Department of Transportation.

The project was originally scheduled to take 19 days and finish by 5 a.m. Aug. 30. Instead, it is projected to finish Aug. 25. For each day the contractors finish early, they will get a $100,000 bonus, said Myly Posse, a DOT spokeswoman.

Preedy said Concrete Barrier has been adding workers, so it now has more than 70 on the job in the one-mile stretch from South Spokane Street to Interstate 90, where they are resurfacing the lanes and replacing damaged steel expansion joints between sections of the elevated roadway.

Friday morning, drivers will shift to the right side of the road deck so workers can shift to the left half.

Three lanes will be reduced to two, just as commuters are getting back into the habit of driving.

Traffic is likely to get worse, the DOT says.

Drivers should know that one of the two open lanes is the merge-exit lane to Dearborn, James and Madison streets. Many are confused and making sudden lane changes there. There’s no need for panic, because the lane re-connects to northbound I-5 downtown.

After two days of light travel, the backups on Wednesday reached as far as the Albro-Swift exit. About 20,000 cars entered Seattle on I-5 from 6 a.m. to 10 a.m., compared with 16,000 Monday.

Transit use on Sounder commuter trains remains higher than usual, but morning counts decreased Wednesday to 4,956 passengers northbound, down 1,763 from Monday’s record of 6,719.

A fast-track job

Finishing road projects early isn’t unusual, the DOT says. The Bellevue Access Downtown Project, to build ramps and overpasses on Interstate 405, finished a year early and $25 million under budget.

The widening of Highway 9 at Sumas, near the Canadian border, finished a year early in 2006.

And Concrete Barrier won a $75,000 bonus when it finished four days early on a repaving job in 2001, on northbound I-5 at Northeast Ravenna Boulevard.

Concrete Barrier was the only bidder on this month’s job. To meet a state-imposed 19-day construction limit, the company chose a fast-setting polyester concrete, which Preedy said can be used a mere two to four hours after paving — compared with several days’ wait with standard concrete.

As workers apply the pavement, a pungent chemical odor drifts into cars passing by.

Rain is possible this week, but not expected to last long. Crews will have a machine to dry the road deck, if needed. Preedy said it would take a five-day downpour for the project to break its Aug. 30 deadline.

Mike Lindblom: 206-515-5631 or mlindblom@seattletimes.com; Susan Gilmore: 206-464-2054 or sgilmore@seattletimes.com