EVERETT — Traffic on I-5 is about to become a royal pain in the asphalt.

On Monday the state Department of Transportation will begin work on a nearly year-long project to replace the aging bridge expansion joints over the Steamboat, Union and Ebey Sloughs.

According to the department, more than 60,000 vehicles use that stretch of I-5 in both directions each day.

A total of 41 joints will be replaced in the $6.8 million project. The contract was awarded to PCL Civil Constructors of Bellevue.

Expansion joints allow the concrete sections of a bridge to expand and contract in response to changes in temperature and traffic loads. If a joint is damaged or fails, it can cause a bridge to bend, crack or even collapse.

The bridge expansion joints are up to 30 years old. Most of the joints have cracked and their seals are broken. Some bolts are missing. Water also can leak onto the bridge girders, causing them to corrode.

Work will be conducted overnight through the end of the year, and then on eight weekends in the first part of 2016, but department officials are asking drivers to start thinking ahead.

“It’s a very difficult area but that’s why we want drivers to start thinking now,” said department spokeswoman Kris Olsen.

“Especially for those weekends. It’s a couple months off but they’ll be here before you know it,” she said.

There are no surface street crossings over the waterways. Only Highways 529 and 9 are viable alternatives for north-south through traffic.

Olsen said the department plans to work to minimize disruptions as much as possible. It has been coordinating with the Tulalip Tribes’ 116th Street NE overpass and with Everett’s Broadway Bridge replacement project.

“Our schedules should coincide nicely, so that when that reopens we’ll be gearing up for those weekend closures,” Olsen said.

The city of Everett began dismantling the Broadway Bridge in February. The city is currently working toward a tentative completion date in February or March, depending on the weather and other scheduling issues, said city engineer Ryan Sass.

So far, the detours around the Broadway Bridge have done their job and a midtown traffic nightmare has not materialized, he said.

“It’s been a nonissue, which is really what we wanted,” Sass said.

Sass said that there probably will be some additional traffic passing through on Broadway due to the work on I-5, but he doesn’t expect too many problems.

“They’ve coordinated well with us,” Sass said of the transportation department.

Work is scheduled to start on the I-5 Union Slough bridges next week. It will last through December, with lane closures starting as early as 7 p.m. on the southbound side or 8 p.m. on the northbound side.

All lanes are scheduled to reopen by 5 a.m. each morning.

“We will not shut down the entire thing. There will always be at least one lane open in the overnight hours,” Olsen said.

In January, the work will shift to the Steamboat and Union Slough bridges, and will take place around the clock on the weekends. The joints in those bridges are larger and require more work to remove and replace.

The contractor is scheduled to complete the job in eight weekends of work, although those dates have not been identified yet, Olsen said.

The crews won’t work on holiday weekends such as Memorial Day, she added.

Lane closures are only scheduled for one direction each weekend.

Updates to the project will be posted on the transportation department’s project page: wsdot.wa.gov/projects/i5/unionsteamboatebeybridgerpr.

Chris Winters: 425-374-4165; cwinters@heraldnet.com. Twitter: @Chris_At_Herald.