For those traveling between North Seattle and South Snohomish County at night, the concrete rehabilitation project taking place on Interstate 5 from from Northeast 117th Street to the State Route 104 exit “continues to make progress,” the Washington State Department of Transportation said in a update issued Friday.

“This work must be done at night to reduce traffic congestion. This section of I-5 carries more than 180,000 vehicles each day. Contractor crews need to close several lanes to provide room to work and keep the workers safe. Closing several lanes of I-5 during the day would create massive congestion and delays.”

The WSDOT update also said:

“Right now, they are working on the noisiest part of the rehab – grinding the concrete,” the update noted. “Concrete grinding is unavoidably loud, and it’s difficult to dampen the noise since it’s a moving operation. The grinding removes a thin top layer of concrete to reduce wheel ruts and reveal a new surface that provides better traction.

This section of I-5 is 50-years-old. It was only intended to last 25 years before replacement began. Since we don’t have the funding to replace it, grinding is the best technology we have to extend the interstate’s lifespan.”

The tentative schedule looks like this:

By March 27: Completion of the northbound section between Northeast 145th and Northeast 175th.
Late March/early April: Tentatively scheduled to be working northbound between 175th and the King-Snohomish County line.
Mid- to late April: Northbound lanes and ramps complete. Work then begins in the southbound lanes.
Late summer: Southbound lane grinding complete.

This is a general time frame that could be affected by weather and other factors, WSDOT notes.