In an effort to complete roadwork before more cold and wet weather arrives, the Washington State Department of Transportation said it plans to close several lanes and ramps on southbound I-5 between downtown Seattle and Spokane Street to replace the right side of four expansion joints as part of its Revive I-5 work. Here are the details:

8 p.m. Friday, Sept. 24 to 5 a.m. Monday, Sept. 27

• Two left lanes of mainline I-5 will remain open.
• People will be able to use the collector/distributor to reach off-ramps at Dearborn, I-90, Fourth Avenue South/Edgar Martinez Drive and Airport Way. All C/D traffic will have to exit before or at Airport Way.
• The following on-ramps to southbound I-5 will be closed:
  • Spring Street
  • The collector/distributor
  • Both directions of I-90
• Off-ramps to Forest Street and Columbia Way/Spokane Street will be closed.

You’ll be able to go into the collector/distributor Sept. 25-26, but you’ll need to use an exit to SODO or I-90. The off-ramps to Forest Street, Columbia Way and Spokane Street also will be closed.

WSDOT also plans lane reductions Friday night, Oct. 1, to early Monday morning, Oct. 4. With that closure, they’ll again funnel all traffic through the collector/distributor so that crews can replace the left side of several expansion joints. While the I-90 ramps to southbound I-5 will be closed most of the weekend, they will be open for a couple hours after the Sounders and Mariners games to give many people their usual route out of the stadium district.

Why weather matters
Last weekend, WSDOT contractor C.A. Carey postponed Revive I-5 work southbound between I-90 and Spokane Street because of rain in the forecast. This project includes polyester concrete, which uses a polyester resin binder with sand and aggregate rock to create a more durable driving surface.

The contractor has already paved 1¼ miles of southbound I-5, but when they install each of the 40 new expansion joints on this section of I-5 they will use the polyester concrete to hold the new joints in place.

When crews worked during the June heatwave, they had to wait for the existing road surface to cool before paving with the new polyester concrete.

While polyester concrete is more durable, it’s also more weather-sensitive than regular concrete, which can handle cooler temperatures and even a little rain. With polyester concrete, if there is any moisture – even from dew – the concrete may not cure properly. Also, temperatures need to be between 50 and 100 degrees. That was a factor when crews paved during the June heat wave. The contractor had to wait until late into the evening for the surface to cool before they could pave.

About those bumps on southbound I-5 …
Anyone who has driven southbound I-5 between I-90 and Spokane Street in the last couple months knows there are bumps at each expansion joint where WSDOT repaved the freeway. The old joints are typically an inch or so below the new road surface. As crews replace the joints, they are making the new ones more level with the new roadway.

Looking across I-5 from ground level, a 4:1 grading at each expansion joint will lessen the bump.

WSDOT did the paving first because it’s easier to match the new joint height to the new pavement than vice versa. Piecemealing this process – doing a little paving here and replacing a few joints there – would have greatly increased costs and the time needed to complete this work.

Contractor C.A. Carey is now working to lessen these bumps, WSDOT said. They are grinding a 4:1 bevel on both sides of each joint. That means for each inch of drop, they shave the surrounding concrete at an angle back four inches, creating a little ramp. There still may be a bump, but it won’t be as sudden.

It’s going to take until fall 2022 to complete all of this work, but in the end you’ll have a smoother ride through this section of I-5. This is just one of many projects WSDOT is doing in the next decade to Revive I-5.