Every once in a while, an election comes along that decides not just the next four years but the next 20. When it comes to transportation, 2008 will be one of those years.

For a dozen years voters have grown impatient as their taxes grow higher and their commutes grow longer. This year they will make a decision that takes them in one direction or the other for the next generation.

Last week’s column covered Dino Rossi’s transportation plan, which was released in mid-April. He would embark on the first real expansion of road building since the 1960’s, adding lanes on heavily traveled roads, bridges and highways. Decisions would be driven by one clear principle: reducing traffic congestion.

The $15 billion plan would be paid by existing gas taxes, stopping the imposition of the sales tax on transportation projects, and using just under half the sales tax collected from the purchase of new and used vehicles to road projects. That would give the state General Fund 2 percent to 3 percent less revenue than it would otherwise receive over a 10-year period.

A few days ago we got to see the progressive alternative to the Rossi Plan.

Tolls. Not just on new roads but virtually everywhere (Rossi would toll an expanded 520 bridge at about $1.50, upon completion).

The Puget Sound Regional Council released a study suggesting that congestion could be substantially reduced by tolling just about every road with a yellow line down the middle. People’s vehicular movements would be tracked by GPS and cellular technology. A toll account would require car owners to pre-pay into the account and have the tolls deducted from it.

The report, “Traffic Choices,” arranged for people in 275 households throughout the Puget Sound area pay tolls over an eight-month period. The people in the household were given between $600 and $3,000 in their tolling account, and were allowed to keep what they didn’t use over an eight-month period. Tolls ranged from zero in the middle of the night to 50 cents a mile on the freeway during rush hour. Sure enough, people changed their driving habits, and most made some money.

The study’s main author, Matthew Kitchen, says that if this concept were extended to all households, the commute from downtown Bellevue to Tacoma would be cut from one hour and eighteen minutes to just 46 minutes. But the one-way toll to get there would be $13.41. It would be a powerful inducement for people to get out of their cars. It would also cost the average commuter thousands of dollars per year beyond the gas taxes they already are paying.

“I have no doubt we’re going to go down this road,” says Aubrey Davis, former Chairman of the State Transportation Commission and a former mayor of Mercer Island. “I just don’t know how far or how fast.”

No elected officials have called for the tolling plan yet, especially during an election, but Ron Sims is an enthusiastic booster of widespread tolls on existing roads, and we see the idea slowly taking shape in the so called “HOT Lane” on Highway 167, which will charge a toll for single occupant drivers to take the HOV lane back and forth to work.

For liberal Democrats, the concept is a two-fer: a new tax on something people pay for already (through the gas tax), plus fewer people in cars, hence no need to expand 405, 167, Highway 18 or any other highway.

So there are your choices to reduce congestion. One way or the other, a very clear choice.