By far the worse of these two bad choices is a new double-decker elevated viaduct, which would average 71 percent larger than the current viaduct and cast a 50 percent larger shadow. In Pioneer Square on the south end of downtown, the existing viaduct is 54 feet wide and about 55 feet high. At the same spot, the new elevated viaduct would be more than 120 feet wide, dwarfing the historic piers on one side of Alaskan Way and the historic buildings of Pioneer Square on the other.

Many people who support a new elevated viaduct say they enjoy the "jaw-dropping" views of downtown that are visible on the way in from West Seattle. Whether or not the views would remain is unclear; however, surely there are more inspired ways of experiencing our city than from a car driving past it.

Building a new elevated viaduct would defy the very principles enshrined in Seattle's commitment to meet or exceed Kyoto emissions standards. If we tear down our elevated waterfront freeway and replace it with an even taller, wider, more obstructive elevated freeway, Seattle will have abdicated the right to call itself an environmentalist, "world-class" city. No city in the world is building a new elevated freeway; in fact, 85 cities worldwide -- from Chattanooga, Tenn., to Sydney, Australia -- are tearing them down.

So can we.

Pro-freeway Seattle hardliners always claim that Seattle is somehow exceptional -- that our "pinched" geography necessitates two big north-south freeways through downtown; that people here won't ride transit because the weather sucks; or simply that because we've never tried doing things differently, like switching from cars to transit, it'll never happen.

Bullshit.

San Francisco is compact, too, and they have transit; Berlin has lousy weather, too, and they have transit; and no city has transit -- until it does. The decisions we make today will determine whether the transit improvements the city makes to accommodate viaduct demolition become a way of life in Seattle or if transit here will continue to consist of an inconvenient, unreliable system of buses that are only used by people who can't afford to drive.

Some local environmental groups have endorsed the mayor's moribund tunnel. But although the tunnel is (arguably) prettier than the viaduct, it's still just another freeway. It still preserves capacity for 130,000 cars, making it little better, from an environmental standpoint, than the elevated viaduct.

Moreover, there's a better way. Instead of spending our limited transportation tax dollars on more concrete for cars, we should be doing what cities across the country, from Milwaukee, Wisconsin, to San Francisco, to Portland, Oregon, to Chattanooga, Tennessee, are doing, with universally positive results: tear the viaduct down, implement all the improvements to transit and surface streets we're going to be doing anyway during the 9 to 12 years the viaduct will be closed for construction, and see if we can get by without it permanently.

Tearing down the viaduct would be more than just a symbolic gesture toward reducing auto dependency; it would give our city an incentive (and perhaps money) to come up with real alternatives to driving, alternatives that we might be able to afford if we weren't spending all our money building freeways. Building any kind of freeway on our waterfront, especially an elevated one, should be unthinkable at this time of rapid climate change and rapidly increasing congestion. There's nothing visionary about it.