Brightwater Tunnel from Point Wells to Ballinger Way nearing completion

The tunnel boring machine (TBM) that was launched in the fall of 2008 from Point Wells in Woodway is scheduled to complete its one-year, four-mile drive this February when it reaches the receiving portal at Ballinger Way and NE 200th Street in Shoreline.

The tunnel is now more 93% complete and has less than 1,500 feet to go.

In the coming weeks, when the TBM approaches the Ballinger shaft, it will be 210 feet below ground. When it reaches the shaft, it will first push through a stabilized column ground that has been frozen before it comes up against the concrete receiving shaft. The ground surrounding the shaft is frozen due to the high water content in the soils.

Crews load concrete segments onto a small tunnel train.  The segments are transported to the head of the tunnel where they are used to complete the tunnel lining.


When the drive is complete, the TBM, its equipment and more than 300 feet of trailing gear will then be lifted in segments to the surface. It will be shipped from the site by truck. The shaft will then be used to receive another TBM now on its way from Kenmore.

Construction hours on the Point Wells to Ballinger tunnel will continue Monday through Saturday from 7 am to 12:30 am until the tunnel drive is completed. Occasionally, underground construction will run longer depending on conditions and necessary maintenance stops.

For more information about Brightwater, visit the website.

If you have questions, please call the Brightwater construction hotline at 206-205-5989 or email.