Why do we clean the SR 305 Agate Pass Bridge?

By Doug Adamson

Updated: January 27th, 2023

There's a lot of work that needs to be done to keep bridges in good working order. This includes regular cleaning of the span that carries State Route 305 over Agate Pass, connecting Bainbridge Island to the Kitsap Peninsula.

It might be difficult to picture, but a lot of dirt can accumulate on the bridge. Plants and grasses can take root.  All can obscure key elements of the bridge which need to be clearly visible to our inspectors. Bridge cleaning also is an opportunity to make repairs before they become a problem.

What should travelers expect?

2023 Update

It is that time of year. Beginning Monday, Feb. 13, Washington State Department of Transportation crews will return for daytime work on SR 305 Agate Pass Bridge. As our crews care for this key bridge, we once again ask for your continued help to keep people moving.

This year, 7 consecutive days of cleaning and maintenance will begin Monday, Feb. 13. It will be followed by a week break in work. Then, 4 consecutive days of inspections are scheduled start Monday, Feb. 27. Work is planned 8:45 a.m. to 2 p.m. each weekday and 7:15 a.m. to 2 p.m. Saturday and Sunday.

We work to keep traffic moving as much as possible but for the crew's safety it will be one-way alternating traffic across the bridge. That's a challenge with thousands of vehicles a day using the bridge. If you're among them, expect delays of at least 30 minutes. Law enforcement will provide traffic control at the intersection of SR 305 and Suquamish Way Northeast so please stay alert for them and follow their directions to keep everyone safe. They may temporarily let one direction through for longer periods of time to help mitigate major backups.

We need your help. Please consider cancelling discretionary travel over the bridge during the work. Otherwise plan for a least 30-minute delays. If you're catching a ferry, plan plenty of time to get to the terminal.

Crews use an Under Bridge Inspection Truck for bridge cleaning. It's delicate, precise work and
needs to be done during daylight for the workers' safety.

How will the bridge be cleaned?

A lot of people work at once on the bridge. Crews use specialized trucks called Under Bridge Inspection Trucks (UBIT) that reach areas under the bridge. An operator skillfully navigates a crew carrier through the elevated steel truss bridge. The crew then uses an articulated arm to move beside and under the bridge. For safety, it's work that can only be performed during daylight hours.

Once in position, the dirty work begins. They use hand tools to scrape away dirt, debris, and animal droppings. It is a labor-intensive process at dizzying heights. To protect water quality, crews scoop up the debris and haul it away. After hand-cleaning is complete, the bridge gets a rinse of water.

After the hand cleaning of the bridge is done, the bridge gets carefully washed down.

Is there other work?

The bridge cleaning is a chance for maintenance crews to do a lot of other work. During the yearly cleaning, workers also make needed repairs and patch the roadway. They may also seal bridge expansion joints, replace rivets, and remove rust. Every other year, the bridge undergoes an in-depth inspection.

While the bridge is being cleaned, our maintenance crews take the opportunity to do
other work like cleaning out drains.

Why doesn't work take place at night?

We do a lot of work at night. If we could do it here, we would, but it's not possible. Our crews need to thread an articulated boom through steel truss members of a bridge. After that, crews maneuver that boom under the bridge deck in very tight quarters. For their safety, we need to do it in daylight.

Why is the work being done in February?

This is a great question! A couple reasons. First, we need to get this done before the busy summer travel season. Also, peregrine falcons have nested on the bridge and doing it now avoids their nesting season.