We’ve always suspected some elected officials of having tunnel vision. How right we were.

The latest example is the “deal” to replace Seattle’s Alaskan Way Viaduct with a deep-bore tunnel. As trumpeted this week by Gov. Gregoire, King County Executive Ron Sims, Seattle Mayor Greg Nickels and Port of Seattle CEO Tay Yoshitani, the plan is to dig a 54-foot wide, two-mile tunnel along the Seattle waterfront.

Cost? $2.8 billion.

But wait, there’s more.

More money specifically – lots of it – and everyone here in the suburbs will have to pony up. That’s the problem.

Gregoire says the state has the $2.8 billion for the tunnel, but that’s not exactly true. Of the total, $400 million is being jerked back from the 520 bridge replacement project.

Also, only 1 percent of this project has been engineered. The state says it will pay for cost overruns, but you know what that means – taxpayers do.

It gets worse, and more expensive, too.

Because the tunnel only would provide two lanes in each direction, instead of the three lanes each way now on the elevated viaduct, Metro Transit wants more buses to haul passengers. Also, the tunnel won’t allow connections to some Seattle neighborhoods. That means more buses still.

To pay for this, Metro wants the county to impose 1 percent motor-vehicle excise tax on everybody in King County. You say you have a car worth $20,000? Get ready to be soaked $200 to let Seattlites drive underground. (Oh, by the way, you won’t get to vote on this, either.)

The Port of Seattle is looking to chip in $300 million for an interchange in Sodo that would benefit waterfront freight traffic. Since the Port collects taxes from everyone in King County, you’ll pay for this, too.

All of this assumes there won’t be glitches along the way. We wonder. Already Speaker of the House Frank Chopp – from Seattle, by the way – is comparing the tunnel to Boston’s Big Dig, where cost overruns push the final figure to $14 billion.

While Seattle’s project isn’t as big, cost overruns are a warning that should be considered.

Finally, the push for a tunnel is basically to make the Seattle waterfront pretty. That’s fine, but Seattle residents should pay the extra costs involved and leave suburban pocketbooks alone.