Washington State Department of Transportation bridge engineers have scheduled an additional in-depth inspection of the State Route 99 Alaskan Way Viaduct on Saturday, March 22.
During the viaduct’s most recent inspection on March 1, engineers observed new cracks, as well as movement and widening of existing cracks along girders and supports near Spring and Seneca streets. While the viaduct remains safe for travel, engineers need a second inspection to gather more information about the cracks before they can make repairs. The inspection requires a one-day closure that will take place Saturday, March 22. Details of the closure will be available soon.
During the March 22 inspection, engineers will conduct an in-depth evaluation of the area, perform tests to determine how the cracks respond to heavy loads on the viaduct, and look for other issues. They will also install monitoring devices on the columns to track the movement and growth of the cracks over time. They will use this data to help identify potential repairs. If additional work is needed, such as filling the cracks with epoxy, further closures will be required.
This section of the viaduct is more than a half-mile north of the current location of the SR 99 tunneling machine. While the cause of these cracks is still to be determined, it is not related to tunneling activity.
No other significant changes to the viaduct were observed during the March 1 inspection.
The Alaskan Way Viaduct is a 60-year-old structure that requires constant maintenance and attention to stay in service, which is why we inspect it four times each year. It is also why we are building a tunnel so it can be taken out of service before the next significant earthquake. Safety is our top priority and we will continue to work to ensure the viaduct remains safe for drivers.