Cary Moon is director of the People's Waterfront Coalition.

Still on the fence about the tunnel referendum because you (a) hate arguing, (b) aren’t sure other options are viable, or (c) feel like it’s too late to turn back now?

This is for you.

Why the Washington State Department of Transportation is so wrong: The Alaskan Way Viaduct viaduct may be a highway, but drivers mainly use it for short and local trips. In fact, 85 percent of trips on the viaduct start and end on Seattle city streets—in thousands of various locations.

This makes the viaduct a different animal than the highway trips WSDOT typically deals with (on I-5, I-90, etc.). And unfortunately, the forecasting WSDOT relies on to predict travel demand is a joke.

Much has been written about the inaccuracies, optimism bias, and persistent myths of traffic forecasting. If WSDOT were to look at real data instead of relying on forecasts, some interesting things would pop out.

1. Car travel in our region has been decreasing for a decade, and we now drive 14 percent less per capita than we did in 2000.

2. Gas prices are rising; more people are choosing low-mileage lifestyles, and young people are about 25 percent less likely to have a drivers license than their parents.

3. When highway capacity is reduced in an urban system, extensive research shows people adjust and life goes on. In “Disappearing Traffic: The Story So Far,” a study of more than 100 capacity reductions, researchers discovered a quarter of trips don’t reappear in the system after a highway facility is downsized or removed. From the study:

”The findings suggest that predictions of traffic problems are often unnecessarily alarmist, and that, given appropriate local circumstances, significant reductions in overall traffic levels can occur, with people making a far wider range of behavioural responses than has traditionally been assumed.”

WSDOT doesn’t seem to understand any of this. Instead, their models that dumb everything down to a few coarse assumptions, like these:

· Car travel in Seattle will increase by 20 percent from 2005 to 2015. Serving these pretend trips is essential.

· No human will ever—ever—decide to choose an alternative to driving. Instead, they will sit in traffic jams day after day, never using their brains to make a more efficient, time-saving, or lower-cost choice.

· Only streets and highways exist as travel options. Bikes? Buses? Vanpools? Scooters? Sidewalks? These are mythical creatures, like unicorns.

· Greenhouse gas emissions and the state mandated reduction of vehicle miles traveled are not WSDOT’s responsibility. (“Hey, we just build the roads — it’s up to you to decide not to use ’em!”)

Why the I-5/Streets/Transit solution will work:

Ignore the scare-mongering about crippling gridlock. Seattle Department of Transportation and its consultants from Nelson\Nygaard have done a ton of work to identify what mix of projects would let us get by without the viaduct.

In 2008, Nelson\Nygaard used some modeling to test ideas, but the bulk of its findings came via professional knowledge, experience, and most importantly, digging through actual data about viaduct usage. From the Seattle DOT and Nelson\Nygaard research, the main categories of investment are:

· A four-lane, connected urban street on the waterfront that will be the same size—and handle the same traffic volumes—as the street accompanying the deep-bore tunnel.

· Enhanced street grid to increase connectivity — especially around Mercer and Spokane streets — to allow some trips to distribute to other streets with unused capacity.

· Coordinated signal timing and improved flow at downtown intersections.

· Transit priority at key bottlenecks, including the addition of more priority lanes and increased transit service on prime routes.

· Additional high-speed transit service from Aurora to downtown, Ballard to downtown, and West Seattle to downtown.

· Demand management strategies like increased transit pass incentives, parking pricing, parking information systems, and rideshares.

· I-5 improvements such as optimized downtown ramps, restriping to add a northbound lane, and additional Intelligent Traffic Management to improve flow. (New capacity for 30,000 trips a day!)

· Freight-mobility investment to increase east-west access between the rail yards, I-5, I-90, and the Port of Seattle.

· Expanded bike facilities and improved pedestrian connections at arterials.

What will all this mean to traffic in Seattle? Well, about 25 percent of current viaduct trips will use the new Alaskan Way. 20 percent would shift to other north/south routes with new capacity (a barely noticeable increase, like two cars a minute during peak periods). About 20 percent would shift to transit, another 20 percent of trips would disappear altogether, and roughly 15 percent would go to I-5.

In other words, the city of Seattle will survive.

Why I-5/Streets/Transit is a better for Seattle’s future.

Set aside the fact that many cities are already transforming their transportation networks into better streets, compact growth, more connectivity, and faster transit. The I-5/S/T approach is just flat out cheaper.

How much cheaper? Try $700 million less than the deep bored tunnel — if, magically, the tunnel comes in on budget. Which it won’t. And I-5/S/T is also simpler to engineer (no boring machines, which have a tendency to break down), faster to implement, and better for the environment.

But it’s not just me who believes I-5/S/T would be good for Seattle. From the “I-5/Surface/Transit Hybrid Scenario” fact sheet currently found on WSDOT’s own website: The city, county, and state highway officials united in recommending a variation of I-5/S/T at the conclusion of the 2008 stakeholder analysis because “it offers a lower-cost SR-99 option that maintains the economic vitality of the city and region while reconnecting the city's historic waterfront with downtown."

Why you should care.

What matters most in all of this— and every public investment decision—is vision. What is Seattle trying to accomplish? What does the future demand of us?

Like other cities, Seattle’s goals include increasing access to urban centers for freight and people, decreasing emissions from vehicles, making streets friendlier for bikes and pedestrians, reducing traffic fatalities, offering people affordable alternatives to driving, creating a kick-ass new civic waterfront, and attracting the employers that will sustain the next economy.

That’s a lot of goals, and after two years (and untold millions in public money) WSDOT has failed to make the deep-bore tunnel scheme workable for our city’s future. In that time, the idea of replacing the viaduct with a massive hole went from dubious to outright preposterous. Dig this:

As many of you know, the tunnel will have no exits downtown (even though a majority of current viaduct traffic currently ends on Seattle streets). Two-thirds of current viaduct travelers won’t even use it. A few narrow, fragile streets in Pioneer Square will be flooded with over 50,000 cars a day. The promise of new transit services was already broken, and existing transit will get worse. There’s no plan to connect downtown to the highway interchange. And just taking the tunnel will cost drivers nearly $8 in tolls for a round trip.

WSDOT has known about these fatal flaws for over a year, but they still don’t have plans or funding—or even intentions—to fix them.

If you care about the future of Seattle, this is the fight you face. Yes, it’s dismaying to admit the tunnel plan isn't working out. Yes, it’s frustrating to be the city that can’t stick to a decision. But we need to cut our losses now and get on with a solution that is pragmatic, responsible, and constructive.

The citizens of Seattle deserve to vote.