Two floating bridges across Lake Washington connect Seattle with its eastern suburbs. The roadbeds rest on huge pontoons and sway a bit as you drive across them on a windy day. One is the last gasp of Interstate 90 as it finishes its journey from Boston to the Puget Sound. The other is State Route 520, or “the 520,” as it’s known.

Which bridge to take where, at what time, using which entrances and exits has long been a major preoccupation of Seattleites, and a frequent icebreaker with strangers. Making the wrong choice about which bridge to take can cost you an hour or more sitting in traffic. Everyone has a pet strategy. (“What I like to do is get off at Montlake and then dismantle the car and carry the pieces up to U-Village, where I reassemble it and proceed up 15th Street…. But you’ve gotta be on the road by 3 a.m. or you’re going to get trapped.”)

All of this changed, though, the week after Christmas, when the state began collecting tolls on the 520 bridge. And it’s not cheap: between $3.50 and $5 each way, depending on the time of day and your method of payment. There’s already a price increase in the works for this summer, from $3.50 to $4.35, one way. The I-90 bridge remains free.

Technologically, the system is a marvel. There are no tollbooths. Indeed, there is no sign at all that this is a toll road except for actual signs that say so. The toll is collected in myriad ways. You can sign up for an account and get a little coded sticker for your windshield. Or you can wait until they bill you, using your license plate to track you down. Apparently, it works. Unless your commute is between 11 p.m. and 5 a.m., in which case it’s free, you can’t escape.

Except, of course by taking I-90. And that — no surprise — is what many people are doing. Now the I-90 bridge is more jammed than ever, but if you’ve got $7 to $10 a day to pay for the privilege, you can sail on the 520 at any time of day.

Economists love this kind of “congestion pricing.” The money raised will be used to rebuild the bridge. Thus this cost will be paid by those who actually use the bridge, in direct proportion to how much they use it. The market will sort out those for whom time is more important than money from those for whom it is not — and give both drivers what they prefer. And of course it’s good for the environment: Some people will reject both the toll and the increased congestion on the free bridge and use public transit or work from home.

Governments around the world are trying variations on this approach. In London, there’s a daily fee on every car driven into the center of town. In Barcelona, there’s a tunnel that speeds you past the worst congestion — if you’re willing to pay.

It’s not a terrible idea. Unlike taxes, these fees are tied to a particular benefit, which makes them easier to swallow. So does the fact that they are voluntary.

Since the toll was imposed, traffic on the toll bridge has dropped about 40%, while traffic on the free bridge has risen 10%. Overall traffic to and from the east side has dropped about 6%.

Does this constitute success? That depends on how you define it. As with the cigarette tax, the more effective a fee is in changing undesired behavior, the less money it brings in. Toll revenue from the 520 bridge is supposed to raise about $1 billion of the $4 billion-plus cost of the new bridge.

But the big problem with the new toll is that it is another small chipping away at our shared life as citizens, and another area where money makes the difference. It used to be that no matter how rich you were, there were some things you couldn’t buy your way out of. Rush-hour congestion was one of them. The law, in its majesty, decreed that rich and poor alike would be stuck in traffic. I once heard Steve Ballmer, chief executive of Microsoft and worth many billions of dollars, talking about his strategy for outfoxing the dreaded 520. I tried it. It didn’t work.

As explained by philosopher Michael Walzer, and somewhat more entertainingly by my friend Mickey Kaus (in his book “The End of Equality”), there are two ways to deal with financial inequality (if it bothers you, that is). One is to reduce it, through the tax system. The other is to make money less important. Create national parks, open to everybody. Restore universal military service. And so on.

By this way of thinking, the two bridges side by side, one costly to use and one free, constitute a small step backward, toward making money more important. You might say, wait a minute. What if there already was a toll on both bridges, and it was lifted on one so that people willing to put up with crowds could go across for free? That wouldn’t seem iniquitous, would it? But it’s the same thing, really.

And I would say, great point! Let’s continue this discussion over a drink downtown. And you would look at your watch and say, it’s too late. We’ll never make it across the bridge before dinner time.

Michael Kinsley, a former editorial page editor of The Times, is a Bloomberg View columnist.