WSDOT said Wednesday the State Route 99 tunnel replacing the Alaskan Way Viaduct could open as soon as this fall. The previous projection was spring 2019.

In a blog post, WSDOT said it was still not able to give a precise date because of all the work that still needs to be done.

"Crews must complete construction of the roadway within the tunnel, and finish installing many interconnected systems that will be required to operate the tunnel. They also must complete a series of thorough tests and certification by the Seattle Fire Department to ensure the systems are working properly. This includes testing approximately 5,000 individual components and nearly 90 tunnel systems," WSDOT wrote.

Although the new date is earlier than the most recent projection, it would still be nearly four years behind the initial schedule. Two years of that delay was due to a breakdown of the tunnel boring machine Bertha while it was already underground. A hole had to be dug down to the cutter head to remove it and conduct repairs.

Once the tunnel is open, the Alaskan Way Viaduct it is replacing will be torn down.