This guest Slog post is by Cary Moon, director of the People's Waterfront Coalition, which advocates a surface/transit alternative to the Alaskan Way Viaduct instead of a tunnel.

OK, Seattle! Listen up. Now is the time to do your second most important civic duty, after voting: Tell the Washington State Department of Transportation what you think of the proposed deep-bore tunnel project. Because for a brief moment, until December 13, they are listening because state law requires them to.

The Supplemental Draft Environmental Impact Statement (SDEIS) is available here, and most the facts of this project are finally visible. It’s a bit grueling to read, yes—but if you care about Seattle, you should try diving in. Certain politicians have been shilling for this project for years: "It’s going to be MAGIC when the cars disappear! We won’t even notice it’s being built!” But 30 minutes with this SDEIS will separate reality from fantasy (for example, see chapter 9 on tolling and its diversion to downtown streets that shows nearly two-thirds of the viaduct traffic won't use the tunnel). You will be furious/deeply cynical/depressed at how the tunnel has been misrepresented.

Here are some of the state's bleak findings:

• Boring a cavernous hole under buildings might cause two historic buildings to fail or collapse, and cause significant damage to twelve historic buildings. Including some of our loveliest buildings along First Avenue.

• Pioneer Square buildings are at risk in general—ground settlement might damage foundations, or altered ground water flows might submerge sub-surface structures or flood basements. Not just during construction, but anytime. (That would make the Underground Tour super fun.)

• The tunnel alternative doesn’t even try to replace access into downtown. This is crazy, considering this is the primary function of the viaduct, and downtown is our state’s core economic engine, and a huge job center.

• There are currently seven on and off ramps from the stadiums to Belltown with the viaduct, but the tunnel condenses them into one highway interchange next to Pioneer Square. Attracting 50,000 vehicles per day on narrow, calm streets. Without telling us what they will do to "improve" these streets.

• With $4 tolls, WSDOT admits half of the daily trips on the existing viaduct will divert to surface streets.

• There is NO transit included in this project at all, despite the governor's promises in 2009.

• The whole project is justified by WSDOT’s predictions that demand for car travel is growing, which ignores some basic facts. Most notable: Use of the viaduct has been flat for 12 years; lots of analysis predicts people will continue to drive less, not more; and the city and state policies directing agencies to reduce vehicle miles traveled, not increase it. And bonus: During the entire 4.5 years of construction, portions of the viaduct will operate at two-thirds capacity and 25 to 40 mph speeds; THAT volume of traffic will be the new normal. Advocates of the tunnel act as though we can't live with that reduced capacity, but we're going to adjust to that condition throughout construction. It's further evidence—provided by this document—that the tunnel isn't the boon we've been promised.

So you have till December 13 to write WSDOT a letter. You can also attend one of the public meetings held tonight, tomorrow, and Thursday (where you can leave your comments with a court reporter). Point out the flaws in their preferred alternative as the EIS describes it, demand the project include access to downtown, and demand solutions to the havoc this designs would create around Pioneer Square. Point out that it would be prudent to have a viable back-up plan in the EIS that keeps the same four-lane street on the waterfront, in case the tunnel proves infeasible.

Make clear to WSDOT that if they want to build their tunnel, they have to (a) do it without destroying Pioneer Square, (b) provide good access into Seattle (hint: transit would be mighty helpful), and (c) show how they can fully pay for all the protection against and mitigation for the messes their project creates for Seattle.

In fact, you can click here to send your email to WSDOT and the mayor, SDOT, and the City Council members, too.