Here’s the details on the costs of the various viaduct proposals (from the WSDOT website):
|A: Surface Boulevard||$800 million|
|B: Surface Boulevard||$800 million|
|C: Surface Couplet||$900 million|
|D: Independent Elevated||$1.6 billion|
|E: Integrated Elevated||$2.2 billion|
|F: Bored Tunnel||$3.5 billion|
|G: Cut & Cover Tunnel||$2.7 billion|
|H: Lidded Trench||$1.9 billion|
Not suprisingly, the surface options are cheapest. These don’t include $1.1 billion in so-called “Moving Forward” costs, which are the projects related to strengthing the most northern and southern pieces. Those projects have already started.
C was my favorite, and is only slightly more than the absolute cheapest. Dino Rossi’s bored tunnel was by far the most expensive.