This isn't easy to admit, so let me just plunge right in: I was wrong about the monorail.

Not wrong that Seattle needs true rapid transit. Or that an elevated system is our best bet of getting it. Or that this is a solid route and a technically sound system of trains and stations.

No, what I was wrong about — and it's a doozy — is that this agency could dig its way out of a 30 percent revenue shortfall.

I derided as "naysayers" those who said the agency didn't have enough money to build a monorail. The naysayers were right.

There's no scandal here — yet. The agency is just getting less tax revenue than projected. Officials vowed to make up for it by trimming costs (they failed, as costs grew) and closing tax loopholes (they succeeded, but it didn't do as much as hoped).

This week, we learned how the agency now plans to forge ahead: Borrow lots of money and don't pay it back until much, much later.

It means we'll be on the hook for monorail car taxes for 50 years or more. Worse, it means the magic of compound interest will be working against us, to the staggering tune of $9 billion.

That's right: $9 billion in interest for a $2 billion project.

The monorail folks' defense is that everyone gets a shock when they first see the interest on their home loans. The analogy only demonstrates how bad the monorail deal really is.

Take a home loan of $300,000, at 5.875 percent interest for 30 years. Over its life you would pay about $338,000 in interest — roughly the same as the loan amount.

To get the same deal as the monorail — in which interest is 4 ½ times the loan amount — you would have to pay $1.35 million in interest. Your loan rate would have to be 18.25 percent. Or your loan's term would have to be ... 93 years.

Taking out such a loan would be "totally ludicrous" — as state Treasurer Mike Murphy dissed the monorail's fiscal plan. So far he hasn't found any project with interest costs near this stratospheric.

Some monorail board members insist that putting off payments is a form of "cross-generational sharing," in which multiple generations pay for a project and enjoy its benefits.

I see it as sticking it to the kids. It's like Congress racking up record deficits. Eventually they must be paid.

It's beginning to seem like passing along debt will be the legacy of my generation.

Look, I love the monorail. But this plan doesn't pencil. The only rational paths now are to shorten the line substantially and put it back out for bid, or keep all 14 miles and ask the voters for more money.

Or cancel it. Let's not forget there's another feature of the monorail that makes it superior to other projects — it can still be canceled.

Doing any of these requires the people most passionate about the monorail, on the board and the City Council, to swallow their pride and admit that this train's off track.

It's not easy. It's embarrassing. Just not as embarrassing as saddling your own kids with debt until they're 60.

Danny Westneat's column appears Wednesday and Friday. Reach him at 206-464-2086 or dwestneat@seattletimes.com.