Tuesday, September 22, 2020

Opening the new Thorne Lane interchange – Part 1

Update: September 29, 2020
The contractor has updated their schedule for the opening of the new Thorne Lane "high" bridge. The new schedule shows the bridge will open the week of Oct. 14. WSDOT will provide more information once it is available.

By Cara Mitchell

It's going to take several weeks. You'll need to take some detours. But there's light at the end of the tunnel. The I-5/Thorne Lane interchange in Lakewood is oh so close to opening!

We'll do what we can to minimize closures and detours as much as we can and we ask for just a bit more patience as we reach this big milestone.

Setting the scene and what to expect

Travelers who use I-5 near Thorne Lane and Murray Road currently drive under three bridges – two new ones and an old one. You can take a look at this overhead photo below to familiarize yourself with each new part of this interchange.
An overhead look of what to expect at the new Thorne Lane interchange.

Over the next four weeks, a series of changes will occur as crews open up different sections of the intersection. Note that dates can change due to weather.
  • Week of Sept. 28 
    • Open new Thorne Lane "high" bridge that connects Tillicum and Woodbrook neighborhoods
  • Oct. 9-12 
    • Weekend full closure of Thorne Lane overpass and I-5 ramps
  • Oct. 12
    • Thorne Lane "low" bridge connecting southbound I-5 to Murray Road opens
  • Oct. 16 & 17
    • Demolish and remove old Thorne Lane overpass
To start, we're going to focus on the first phase of work – opening the Thorne Lane "high" bridge.

Opening Thorne Lane "high" bridge

As early as Tuesday, Sept. 29, crews will open the new 344-foot-long bridge that spans both I-5 and the railroad tracks. To keep things simple, we are calling this new bridge the Thorne Lane "high" bridge. It will connect local streets using new roundabouts at Murray Road and Union Avenue.
Here's what travelers can expect when the Thorne Lane high bridge opens late this month.

When the new "high" bridge opens, southbound I-5 travelers exiting to Thorne Lane will continue to use the old overpass to turn right to Thorne Lane, or left to Murray Road. Travelers headed to Tillicum can either continue to follow the existing detour on Thorne Lane to Union Avenue, or use the roundabout at Murray Road and cross the new "high" bridge to Union Avenue. This temporary traffic pattern will remain in place until the weekend of Oct. 9, when crews begin work to open the Thorne Lane "low" bridge. That will be covered in a future blog.

Why roundabouts?

There is a good reason why we used roundabouts on the Thorne Lane high bridge – they move traffic through an intersection faster than a traffic signal. Traffic signals on the existing interchange were a necessary component to coordinate the movements of travelers going to and from I-5, railroad activity, and pedestrian/bicyclist traffic. The complexity of the network of streets with the railroad required signal timing that created substantial delays and backups. 

The new interchange design helps relieve congestion by separating where and how traffic flows. The new high bridge is designed to keep bikes, pedestrians and vehicles moving without the need for traffic signals between Lakewood's Tillicum and Woodbrook neighborhoods. This helps reduce congestion.

Is this part of the SR 704 Cross Base Highway project?

We receive this question a lot. The answer is, No. The SR 704 Cross Base Highway project is on indefinite hold. There is no current funding for the project and because so much time has passed since the first phase was constructed, in 2008, a lengthy environmental review process would need to play out again. 

Moving into fall

Here is a list of work coming up in October both at Thorne Lane and on southbound I-5: 
  • The new Thorne Lane "low" bridge will open, bringing with it several detours.
  • The old Thorne Lane overpass will be demolished, and that will require overnight closures of I-5. 
  • Last but not least, a second traffic switch for southbound I-5 lanes will occur near Berkeley Street as part of raising the elevation of the highway 14 feet. 
Putting hard dates to all this while scheduling around weather is at times like herding cats. We will do our best to provide updates as work progresses on what to expect for travelers in the coming weeks. 

As always, we ask you help keep our crews safe by driving the posted speed limit and be mindful of work zones.