Drivers attempting to cross Lake Washington this weekend should prepare themselves for delays.

All eastbound traffic on I-90 will be squeezed into the express lanes to get across the lake.

Travis Phelps, with the Washington State Department of Transportation, says drivers need to be prepared for heavy slowing between I-5 and the Mount Baker Tunnel.

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“Sometimes that catches folks off guard,” Phelps said.

It’s not just I-90 and I-5 drivers that will get caught up in this. Any time WSDOT makes this kind of closure, it impacts the entire system.

“We’ll see that ripple onto I-5,” Phelps said. “We’re going to see a lot of folks head to 520 and a lot of folks heading around the horn as well. So, just expect regional congestion.”

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Normally, these weekend closures begin on Friday night and last through Monday morning. However, there’s a late Seahawks game on Sunday. Phelps says they are going to try and finish work a little earlier to help fans get out of downtown Seattle without any extra delay.

“We’re going to try and finish our work and help that traffic move smoothly,” he said.

The closure begins at 11 p.m. Friday. The lanes will reopen before the Hawks game ends.

The WSDOT needs what will eventually total 30 directional closures to prepare the tunnels in Seattle and on Mercer Island for light rail service. They need to upgrade all the life safety and emergency systems in the tunnel. Phelps says you should be seeing the results of the work they have been doing.

“You can see we’ve upgraded some lights and initial holes in the ceiling, some that are pretty large,” he said. “Definitely starting to take shape in there.”

As part of this project, WSDOT is going to be adding HOV lanes on the outer roadways to make up for the loss of the express lanes. Sound Transit is going to start laying rail on that center roadway in 2017.

Trains are expected to start rolling to Bellevue in 2023.