The hard truth about tolling Lake Washington

Both Lake Washington floating bridges may have to be tolled in order to pay to rebuild the Highway 520 bridge, says state Treasurer Mike Murphy. That is not welcome news, but people need to know it.

When the 520 bridge was opened in 1963, the toll was 35 cents each way, the equivalent in today's dollars of $4.50 for a round trip. The tolls paid for the bridge in 15 years. But we now look to build a bigger and wider bridge with modern environmental requirements. There is talk of a toll of $10 or more, and for a longer time. Whatever the toll is, it will tend to be less if spread across both bridges. Another reason for tolling both bridges is traffic. A $10-plus toll on one bridge will tend to divert traffic to the other — especially when the toll is charged in only one direction. And that is the plan, which aims to minimize the cost and hassle of toll plazas.

Collecting tolls will not be done the old way, with employees making change — at least, not for most drivers. The idea is to do it with sensors and transponders, so that regular users hardly need to slow down. People will have accounts they can replenish at the bank or online.

None of this is Murphy's concern. His interest is in certifying that the state will have enough money to repay the bonds. And given the Highway 520 project's current scope — six lanes, which are the absolute minimum needed — and the current interest rates and funding sources, Murphy says the revenues are about one-third short. It's early in the process, and that could change. Unless it does, he says, the state will need to toll both bridges.

That may seem unfair to users of Interstate 90, but really it isn't. All who cross the lake will derive value from 520 being rebuilt.

There are other ideas. One is to vary the tolls by time of day, charging more at rush hour, and letting the tolls drop to almost nothing at night. That is demand management, which aims to prevent congestion. But that would require tolling in both directions.

Murphy broached the idea of collecting tolls before the new bridge is built. The state would have to pay less interest that way, meaning the total amount collected from the public could be less. The idea makes sense, though Murphy noted that charging tolls for a bridge that doesn't yet exist is "a radical idea."

Indeed it is. This is the time to get all the ideas out in the open.