Seattle Deep-Bore Tunnel Facts

Referendum to stop tunnel: On the primary ballot - ballots must be postmarked by Aug 16th. Cost of project = $4.2 billion

Tunnel will have no downtown exits Tunnel will be unusable to many of the cars that currently use the viaduct making downtown traffic much worse than if the viaduct was simply torn down. With no exits, and a $4 toll each way, projected traffic volume through the tunnel will be surprisingly small (carrying less than the traffic flow across the Ballard Bridge). (1)

Amount of cost over-run that the City of Seattle will be stuck with WA State legislature was convinced to pass partial funding for the project with the stipulation that ALL cost overruns would fall on the taxpayers of Seattle: see state law .(2) Supposing a very possible 35% cost overrun, Seattle taxpayers would thus be hit with a $1.5 billion tax bill (more than one-third of the city's annual budget) at a time when fundamental, core city services are being eliminated (police, transit, parks, libraries, schools, health care)

Diameter of tunnel = At 54 feet it will be the widest deep-bore tunnel of any kind ever attempted anywhere on Earth (3) (it will be twice the diameter of the English Chunnel)

A risky project, likely to go way over budget: Megaprojects of this scale typically have massive cost overruns. Of 258 recent massive transportation projects, 9 out of 10 ran over their estimates, with actual costs averaging 34% higher than estimated costs. (4)

This project's tunnel-boring machine (TBM) will confront soft soil which tends to cave in behind the machine. As the machine grinds forward, it must simultaneously create a concrete tunnel lining behind it to hold up the earth. Those concrete slabs narrow the diameter of the hole, preventing the TBM from backing up. Tunneling machines thus can't travel in reverse. And if the TBM's blades break, the machine can't move forward. It's stuck. (5) Not only is this the most expensive thing that could go wrong, it's also a fairly common thing that goes wrong. Two TBMs recently got stuck underground in King County. One was immobilized for nine months, and the other hasn't budged in over a year.

If a TBM gets stuck under one of the 390 downtown buildings it will pass under, then a five-story-wide chasm would have to be opened one block away, in the middle of a downtown street, down to the depth of the stalled machine. Another tunnel would then have to be dug sideways to reach the stalled machine, to lift it out so that a new TBM coould be lowered into the hole. This is a cost and time delay that would stretch on for an additional 1-2 years.

Date of referendum: It is on the primary ballot which must be postmarked by August 16. A NO vote will place a new serious obstacle to proceeding with the tunnel. No construction has begun yet.

Best option if tunnel is rejected: a surface option (6) with causeways to open the waterfront, using part of the billions of dollars saved towards improving mass transit and widening I-5 (the tunnel plan provides no funds for mass transit)

Supporting links:

(1) http://www.thestranger.com/seattle/compare-the-tunnel-to-the-ballard-bridge/Content?oid=5788974

(2) http://apps.leg.wa.gov/rcw/default.aspx?cite=47.01.402

(3) http://concurinc.com/wp/2010/12/23/two-major-concur-projects-move-toward-implementation-alaskan-way-viaduct-replacement-and-southern-california-mpas/

(4) http://tinyurl.com/3nl5feo

(5) http://www.thestranger.com/seattle/what-could-possibly-go-wrong/Content?oid=4399657

(6) http://www.peopleswaterfront.org/index.html