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Your trips between Everett and Marysville are about to get a lot more complicated. Four months of construction is about to shut down half of State Route 529.

This is the “big one” Chokepoints has been warning drivers about since the start of the year — a of the 529 northbound span over the Snohomish River at the north end of Everett.

It will close Sunday night and will remain closed until October.

“The bridge is 97 years old, and we need to do some work on the mechanical parts that lift and lower the bridge,” the Washington Department of Transportation’s (WSDOT) Tom Pearce said.

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Both directions of the Snohomish River Bridge will be closed Sunday night so the final detours can be put into place. All northbound drivers will be detoured onto the southbound span starting Monday morning, and it will stay that way for the duration of the work. There will be one lane in each direction.

“We need to do a full closure because we will be removing the pieces that lift the bridge,” Pearce said. “But to allow for maritime traffic, we need to keep the bridge open so we have to leave it in the raised position.”

That will also impact people who walk or bike across the bridge. The walkway on that northbound span will not be available. A 24-hour-a-day shuttle will be available to ferry those people onto the southbound span.

“You’ll be able to go either direction, pick up or drop off either way,” Pearce said. “The service will be in place 24 hours a day. There’ll be a number for you to call to request it. It could be up to a half hour before the shuttle arrives, but there will be a shuttle to take you across.”

There will be cross-overs on either side of the bridge to get drivers into the southbound lane. That will restrict some access for people who use Marine View Drive.

“If you’re headed north, you are going to be able to exit to Marine View Drive,” Pearce said. “However, you’re not going to be able to get on to northbound 529 directly from Marine View Drive.”

Let’s say you’re playing 18 holes at Legion Memorial Golf Course or you’re working at the Amazon Center at the north end of Everett and you want to take northbound 529. You’re going to have to head south on SR-529 from Marine View Drive and use the U-turn detour a few blocks away.

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This work will have a major impact on traffic throughout the area.

“People really ought to stay on northbound or southbound I-5,” Pearce said. “We’re going to see heavier traffic on the freeway. We’re gonna see delays no matter what, but the freeway has a lot more capacity for handling it.”

There is a chance this closure could be pushed for a few days if the weather doesn’t cooperate this weekend. The contractor needs dry weather to put in the final lane striping.

But the weather looks great for the weekend right now.

Check out more of Chris’ Chokepoints here. You can also follow Chris on .Ìý to follow ³ÉÈËXÕ¾ Newsradio Traffic’s profile .