Following the installation of a new permanent replacement span, contractor crews working for the Washington State Department of Transportation will begin upgrading and retrofitting the remaining sections of the Interstate 5 Skagit River Bridge.
A portion of the Skagit River Bridge on I-5 collapsed near Mount Vernon in May after a truck's oversized load struck critical steel supports. This corridor carries 71,000 vehicles daily.
Contractor crews will raise and reinforce the bridge’s overhead structural support system this fall. While this work is underway, crews will also perform maintenance activities, including replacing rivets below the deck and painting.
Currently, the support structure above the travel lanes is curved. This means the vertical clearance over the bridge’s left lanes is higher than vertical clearance over the right lanes. The bridge’s highest vertical clearance is located above the left lanes and measures 18 feet, while the vertical clearance above the right lanes measures 15 feet 6 inches at the fog line.
When crews finish raising and reinforcing the structure by November, the bridge will have an equal 18 foot vertical clearance across all lanes. Several bridge supports will also be retrofitted with reinforced steel components to add strength if the bridge is struck again.
“The truck that caused the Skagit River Bridge to collapse was too tall to be in the right lane, and it struck one of the lowest points on the bridge,” said Jay Drye, WSDOT acting assistant regional administrator. “By raising the vertical clearance above the right lane, we hope to reduce the chances of a similar bridge strike in the future.”
“We expect the volume of oversized loads to continue to grow into the future,” said Drye. “While it’s still the responsibility of the freight hauler to check the vertical clearance of bridges along their route prior to travel, this project will help freight to move through the I-5 corridor with less risk.”
Drivers can expect overnight lane and directional closures of I-5 to complete this work. WSDOT has a camera in place to view the work and will post pictures throughout the construction period.
Workers are building the $6.87 million permanent spans after crews completed work June 19 on a temporary replacement span and reopened I-5 to traffic.
NTSB Releases Report on I-5 Bridge Collapse
Blog: A Bridge Too Low