Wednesday, December 15, 2021

Preservation work on I-5 Stillaguamish River bridge completed

By Meggan Carrigg Davidson

If you traveled on southbound Interstate 5 over the Stillaguamish River bridge in Arlington this past summer you probably noticed a lot of activity. Our contractor, Southern Road & Bridge, LLC, began repainting the bridge and replacing some of the worn 88-year-old original steel that helps support the structure. The bridge's trusses were stripped to bare metal and received a new coat of paint to protect the aging structure for years to come.

While we kept two lanes open in both directions along I-5 during the peak of summer traffic, we know there were some delays and we appreciate everyone's patience while we got this work done!

Work on the southbound I-5 Stillaguamish River bridge was done under a full
containment system to protect the waterway below.

Preservation work was needed

Existing paint on the southbound Stillaguamish bridge was weathered and damaged, allowing corrosion to occur. This project removed old, chipped paint and corrosion, taking the entire bridge back to bare metal for the first time since 1933.

The contractor cleaned exposed metal and applied a total of 2,476 gallons of paint under a full containment system to protect the waterway below. They also replaced two minor steel members and 1,414 rivets and bolts.

Much more than just a matter of appearance, new paint helps prolong the life of the bridge by preventing rust and other corrosion.

Crews used 2,476 gallons of paint and replaced two minor steel members and 1,414 rivets and bolts on the bridge.
Here’s a look at before and after the work.

Where did traffic go during this closure?

From June through October, all southbound I-5 traffic was diverted onto the existing median bypass on the adjacent northbound lanes. This kept both directions of I-5 moving during the preservation work.

For drivers who have been around awhile, you may remember that in 2014 we used the same crossover when the southbound bridge deck was replaced after 81 years of service. It took about four months to complete that work and the bridge reopened in November 2014. During this most recent work, crews were able to utilize the existing median bypass on either side of the bridges to again accommodate this necessary work.

All southbound I-5 traffic was diverted onto the existing median bypass
on the adjacent northbound lanes.

A bit more to do

This coming spring be prepared for some lane closures over a few weeks as crews complete permanent erosion control in the median. This work will include final stabilization and sediment control of the excavated areas.

Stillaguamish River bridge's history

The southbound Stillaguamish River bridge was built in 1933 to carry US 99. When I-5 opened in the 1960s, the bridge became part of the interstate, carrying two lanes in each direction. A new northbound bridge opened in 1971 and traffic was separated, resulting in three lanes on each bridge. The southbound steel truss bridge comprises three spans over the river and spans 607 feet.

Each bridge carries an average of 39,000 vehicles per day, but that can rise to 50,000 per day during the summer.

A look at before (left) and after of the preservation work on the I-5 Stillaguamish River bridge

The rest is history!

This bridge has seen its fair share of normal wear and tear over the years. Again, we thank you for your patience and care during the completion of the restoration work. We are excited to see the bridge back in action for its crucial role in transporting goods and services along the I-5 corridor.

You can check out photos of all the stages of work in our Stillaguamish River bridge Flickr album.