TRANSPORTATION / SCOOTING UNDERGROUND : Ultra-Tech Buses in Seattle Set to Roll--in Tunnel : Opening of downtown subway is intended to reduce aboveground congestion and speed the trip for commuters.

After this week, buses will begin disappearing from downtown Seattle. They’re going underground.

While other West Coast cities--San Diego, Los Angeles, San Francisco, Portland--may see their transit future in rail systems, Seattle has cast its lot with the bus. And Saturday’s scheduled opening of a glittering new downtown bus subway is building up to a hearty round of civic back-patting about the visionaries who kept faith with the utilitarian rubber-tire motor coach when so many others were hellbent to catch the train.

Not that you would recognize Seattle’s fleet of new buses as anything resembling old-fashioned, however.

They are ultra-tech Italian design, 60 feet long, articulated to bend in the center and have both a diesel engine and a 275-horsepower electric motor. The diesel carries them through outlying areas, then electric trolley poles rise and connect automatically to the high-wire power grid in the downtown area. They seat 65, have room for two wheelchairs and cost a dizzying half-million dollars apiece.

The trouble is that buses, even sleek twin-engine ones from the land of Ferrari, take more than 20 minutes to traverse the stop-and-go downtown area. But, beginning Saturday, that is supposed to change.

At a cost of $459 million, a 1.3-mile downtown bus tunnel is opening this weekend in a grand effort to reduce aboveground congestion and speed up the trip for commuters. A bus ride across town next week is supposed to take only a third of the time, eight minutes, instead of a half-hour, and it’s free in the downtown core, too.

Eventually, 40% of the buses that now choke downtown streets will be diverted into the underground tunnel, which has modern high-tech stations rivaling the most glamorous of the modern urban rail subways.

The opening of the bus tunnel promises to bring traffic relief in more ways than one. Construction has knotted up downtown for four years, just at a time when high-rise growth here was exploding. The result has been a severe test of Seattle’s vaunted reputation for “livability.”

“Nice town, why are they tearing it down?” a visiting wag was supposed to have asked.

Seattle’s love affair with the bus has not always been part of the civic dream.

Twice before in modern times, in 1968 and 1970, residents in the metropolitan area refused to approve bonds for rail transit. Some predicted disaster as a result. And, today, some motorists who squeeze onto freeways and bridges for each day’s colossal Seattle traffic jams believe the predictions were correct.

Certainly, people to the south in Portland feel that way.

Always competing with Seattle (metro pop. 2.4 million) to offer a more “livable” city, Portland (metro pop. 1.4 million) opted for light-rail transit to try to ease congestion, reduce pollution and channel growth. That was back in the early 1980s after the public voted down more freeways.

Now, Portland also is facing a watershed event in the history of Northwest transit.

In the November election, residents will be asked to increase property taxes and approve a $125-million bond issue to begin work on a second leg of their MAX, Metropolitan Area Express.

The existing line runs 15 miles to the east. Just as planners predicted, it has directed growth and vitality to that area and came at a time when Portland was renewing its downtown core. Now, however, planners say a new line to the west is essential to further Portland’s rail-not-road growth ethic.

The prospects are uncertain. Oregon voters sounded a warning in May. They said “no” to a constitutional amendment that would have allowed transit funding from motor vehicle fees. That means there is no choice but to seek money from the property tax, and, as everyone knows, that is difficult to sell to voters.

Supporters appeal to pride as well as practicality.

“This is the single most important project in the state,” Oregon Transportation Commission Chairman Michael Hollern told reporters.

Times researcher Doug Conner contributed to this story.