The above assertion was made by Mayor Mike McGinn at last night's packed tunnel forum at Town Hall. He just causally dropped it into a long answer to some question or another, maybe not even knowing what he'd found: The perfect sound bite for this moment.

I'm told that the line—"It costs $2.8 billion, but will move fewer cars than the Ballard Bridge"—has been used before, perhaps during the mayoral campaign, but never quite took off. Well, that was then.

Back in 2009, no one knew exactly how many cars the tunnel might move, so no one really believed anyone who claimed to know. Today, we have an answer, based on the state's own studies: The two-mile-long, $2.8 billion downtown tunnel, because of its tolls and its lack of downtown exits, is expected to move fewer cars than the tiny old Ballard Bridge.

That's a fact that cuts right through all the complication in this endless debate, and says, in plain Seattle language, what the mayor has long been trying (and failing) to communicate: This project just doesn't make sense.

If I were advising him, I would tell him to repeat that line every chance he gets.

This tunnel will cost $2.8 billion—maybe more—but when it's all done, based on the state's own estimates, it will move fewer cars than the Ballard Bridge. How does that make sense?

Hey, you're in favor of the tunnel because you think it will solve our transportation problems, right? Well, consider what we know for sure already: It will cost about $2.8 billion—maybe more—and when it's all done it will move fewer cars than the Ballard Bridge. Sounds like a bad deal to me.

If I told you that for $2.8 billion, I could build you a two-mile-long tunnel under downtown Seattle that wouldn't move any more cars than a 93-year-old, 2,845-foot bridge to Ballard—would you say that was a tunnel you would want to buy?

And so on.