SR 9 Pilchuck Creek bridge replacement project
The single-lane Pilchuck Creek bridge was built in 1916 just north of Arlington in Snohomish County. In 2013, WSDOT will build a wider, stronger bridge, on a new roadway alignment to the west, which will improve sight distance and safety for the 1,300 drivers that use this route daily.

Of the 3,600 state-owned bridges in Washington, this bridge is one of the oldest. At just 17 feet wide, the single-lane bridge is too narrow for modern safety and traffic standards. A yield sign on south end of the bridge helps drivers take turns crossing it.

This type of bridge is called a filled spandrel double-arch bridge, and is commonly referred to as a Luten bridge, after bridge engineer Daniel B. Luten. Often bridges of this type are called Luten bridges even when not designed by Mr. Luten himself. In this case, plans on file at WSDOT indicate that the Pilchuck Creek Bridge is indeed derived from a Daniel Luten design. He was a pioneer in the design of reinforced concrete structures.

The superstructure and substructure are rated in fair condition. All primary structural elements are sound but some deterioration, cracking, spalling, and footing scour can be seen. While the bridge itself remains safe for drivers, it’s time to replace it.

Engineers considered several options for replacing the bridge. They selected a bridge design that will improve sight distance and safety, reduce impacts to the environment and neighboring properties, and be the most cost effective.

The bridge also runs parallel to I-5 and serves as the only major north-south route available if a closure shuts down the interstate.

On April 13, 2011, WSDOT presented design plans and information to local residents at an open house at Snohomish County Fire Station 91.

For more information about the project, go to, call WSDOT at 360-757-5997 or email
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