Do cash incentives alter driving habits?

When he was given a new economic incentive to drive less this summer, Gregg Williams, of Woodway, didn't change his commute a bit.

Offered that same incentive, Bill Tan, of Burien, transformed his life. "I basically stopped driving," he says.

Tan and Williams are guinea pigs in a groundbreaking study that aims to find out how people's driving behavior would change if they had to pay a toll on almost every mile they drive.

Would such a radical move make a dent in traffic? That depends on how many drivers would respond like Williams and how many would respond like Tan.

The 400 volunteers in the Puget Sound Regional Council's "Traffic Choices" study have been paying virtual tolls since July. Devices mounted on their dashboards track where they travel and transmit the information to a central computer. Charges are deducted from prepaid "endowment accounts."

Those accounts are just play money. But if there's anything left in them when the experiment ends in February, participants get to keep it — in real dollars.

That's the carrot. They can save money by not driving as much, by choosing less-congested highways, or by staying off the road at rush hour.

Matthew Kitchen, the study's director, says meaningful results won't be available until late next year. Researchers will spend months crunching the data and adjusting them to account for changing gas prices and other variables, he says.

When they do present their findings, however, they're likely to attract attention around the globe.

Tolls have enjoyed a resurgence in recent years as a potential solution to two related problems: too much traffic, and too little money to build anything to help alleviate it. New technology that makes toll booths unnecessary has accelerated the trend.

Motorists will pay a $3 round-trip toll to cross the new Tacoma Narrows bridge when it opens in 2007. The state Department of Transportation plans to open the HOV (high-occupancy-vehicle) lanes on Highway 167 between Auburn and Renton to solo drivers willing to pay a toll. For nearly three years all cars entering central London have paid a stiff charge; congestion has dropped 30 percent.

The kind of tolling the Traffic Choices study is testing goes beyond any of those initiatives. Participants are paying to drive on every freeway and most arterials from Everett to Sammamish to SeaTac.

No one's talking about imposing a scheme like this for real here anytime soon. Politically, it's a non-starter, policy-makers agree.

But consultants are exploring regionwide tolling as part of a comprehensive study of tolls the Legislature ordered earlier this year. The British government has offered a sweeping plan to place tolls on every road in that country in another decade.

And the Federal Highway Administration was sufficiently intrigued by the Traffic Choices study to pick up 80 percent of its $2.35 million cost.

"There is potential for this kind of system to be implemented somewhere," Kitchen says.

"Endowment account"

Each Traffic Choices driver's "endowment account" is different. Study managers customized them after monitoring volunteers' driving patterns for several months before the tolls took effect.

The charges are designed to discourage driving on heavily traveled roads at peak times. They range from 50 cents a mile on freeways on weekdays between 3 and 6 p.m. to nothing at all between 10 p.m. and 6 a.m.

Tan was given $1,535 to "spend." The first morning he drove the 15 miles from his Burien apartment to his production job at a direct-mail marketing company near Seattle's Fishermen's Terminal, it cost him $3.76.

At that rate, he figured, he'd blow through the money pretty quickly. "I got very conscious about the cost of driving," Tan says.

So he began exploring alternatives.

First Tan, 54, and single, tried driving to work on different streets with lower charges than his usual route. It took 10 minutes longer, he says, but it also saved him about $1 a trip.

In August he began riding with a co-worker, who also lives in Burien, when their schedules coincided. That arrangement fell through this fall.

Now, Tan says, he takes the bus to work about four days a week. It involves a transfer downtown and takes an hour longer than driving, but he likes it. "It's like an adventure. I get to know the city better. ... It's less stressful."

As for the extra time it takes, he says, "I always spent all my time watching TV anyway."

Tan says he drives so little now that he actually got a call from a study manager, asking whether the monitoring device on his dashboard still was working. The last time he checked his account online, it still contained more than $1,300. He's looking forward to a nice check when the experiment ends.

Williams says the demands of his life didn't allow him to change his driving so dramatically. The fisheries researcher lives in Woodway and works on the University of Washington campus in Seattle.

Like other volunteers, he's guaranteed at least $150 at the study's conclusion just for participating. He doesn't expect to get much more.

Buses and car pools don't fit his life, Williams says: He drops his son off at school in Shoreline every morning on his way to work. He could take other streets with lower tolls, he admits but says, "I hate stoplights." Tolls appeal to him in principle, Williams says: "You pay for what you use." But the Traffic Choices tolls haven't altered his life one iota, he confesses. "I just don't have any real opportunity to make any real changes in my driving habits."

Kitchen understands. "If it doesn't make sense for you to make changes, it doesn't make sense," he told 25 participants at a kickoff meeting this summer.

Driving more, paying less

Kitchen says interim results indicate that, as a group, the study's 400 participants actually are driving a bit more than they did before the experiment started. But they're also paying a little less than they would have if the tolls had been in force when researchers first began monitoring their driving.

That could mean the volunteers are avoiding roads with the steepest tolls at times, even if it takes them out of their way, he says. "But we may find something very different when we do a more detailed analysis," he cautions.

The Traffic Choices study already is bringing to light some issues any regional tolling scheme would have to address before it debuts in the real world, Kitchen says.

Just installing the dashboard devices proved a major undertaking. "It was one thing for us to equip 400 vehicles," Kitchen says. "If we ever did it with 3 million vehicles, the logistical problems are clear."

Another problem: The cellular and global-positioning-system (GPS) technology that monitors and records each car's travels has limitations. Researchers decided not to toll any streets in downtown Seattle, for instance, because the "urban canyons" there interfered with reception.

Then there's the big concern that plagues all plans for high-tech tolling: privacy.

Kitchen says the 400 volunteers will be surveyed on their feelings about that before the study ends. Developing a system that is accurate and enforceable, but also politically acceptable, could be a challenge, he says.

Participant Meg Carpenter's car already has OnStar, a commercial, in-vehicle security system that uses similar tracking technology. "They already know where I am," she says.

But requiring such technology in all cars gives her pause: "It's part of the slippery slope."

Eric Pryne: 206-464-2231