The largest lottery jackpot in history inspired Americans to spend $1.5 billion for a slim chance at riches this year. Transportation experts are wagering that this fervor for small gambles can be put to use solving a big urban problem: traffic congestion.

Two experimental transportation projects under way this year in Singapore and Silicon Valley aim to improve commutes through gaming.

Thousands of commuters so far have decided it's worth the effort to change their routines for a shot at $50 or $100.

Traffic congestion wastes billions of hours of drivers' time each year, and adds to the global burden of carbon emissions as cars spew pollution without going anywhere. In the United States alone, the Texas Transportation Institute estimates the cost of gridlock, based on time and fuel wasted, will swell to $900 per commuter in 2015, from $750 in 2010. And the amount of fuel burned in U.S. traffic jams will reach 2.5 billion gallons in 2015, up from 1.9 billion gallons in 2010, the group predicts. With more than 1 billion cars on roads today around the world, a number expected by some to double by 2020, the search for answers is urgent.

Some urban areas, including London, Stockholm, and the capital of Singapore, have tried disincentives to discourage rush-hour driving. These congestion-pricing schemes have achieved some success, but problems persist. And implementing them is politically difficult; New York Mayor Michael Bloomberg abandoned his early effort to pare traffic in the Big Apple through commuter charges. But a growing number of transportation experts believe the same technology that enables cities to track cars and charge a fee when they enter designated congestion areas can be used to implement schemes that people will accept more readily. Rather than punishing old commuting habits, they reward new ones. For participants, opting to avoid rush-hour traffic means both saving time, and boosting their odds of winning a prize.

Credits Per Kilometer

Instead of buying lotto tickets, participants in the Singapore program shift their commutes to off-peak hours to earn credits, which can be traded for chances to win cash. Participants earn one credit per kilometer traveled by rail, and three credits per kilometer for rail trips made during the hour before or after morning rush hour (7:30 to 8:30 a.m.). They can pick one "boost day" per week, when each kilometer traveled by rail earns five credits.

At Stanford, where the project is supported by a $3 million U.S. Department of Transportation grant, drivers who live off-campus and shift their commutes up to one hour outside the morning and evening rush hours can earn 10 cents per off-peak trip. That's the boring, sure-fire option. Alternatively, they can use credits to play a simple online social game that randomly doles out cash prizes from $2 to $50. Cars are tracked using a small radio-frequency identification tag mounted to the windshield.

More than 17,500 Singapore commuters have enrolled in the pilot program, while just over 1,825 have enrolled in the Stanford project. And it seems these efforts to change travel behavior using games, or carrots, rather than sticks (such as congestion pricing) are paying off. Balaji Prabhakar, a Stanford engineering professor who developed both projects, said during a recent talk at the university's campus in Palo Alto, California, that 11-12 percent of users in Singapore have shifted off-peak. Men tend to shift later, he said, while women generally shift earlier.

As Prabhakar ran through slides showing the latest campus rewards data, one student in the audience whispered proudly to another, "One of those is mine." Apparently he had recently scored big in the online chutes-and-ladders game, using his smart commute credit. This kind of social sharing, online or in real life, is part of the dynamic of the program; it's meant to catch on as more and more people know someone who has bought a round of drinks, a tank of gas, or a pricey textbook using cash earned by simply sleeping in.

The 11 percent of participants changing their ways might not seem like much, but they're enough to make a difference in traffic flow. "It takes many people to create congestion," Prabhakar said, "but surprisingly few to get rid of it."

The idea for a rewards-based solution to congestion, he said, occurred to him while sitting in traffic in Bangalore, India. It was there, in 2008, that he first implemented a pilot based on lottery rewards for commuters who shift their travel off-peak. The Bangalore project was limited to employees of one company, the technology-consulting firm Infosys. But the Singapore project, launched in January, welcomed any adult with an EZ-Link transit card (researchers selected volunteers from this pool based on historical commuting data). So far, nearly 103,000 SGD (about $80,500, or 63,905 euros) in rewards have been given to commuters in the form of credits on their transit passes. The vast majority of those credits have been in amounts of just 1 SGD or 2 SGD, but 39 lucky participants have also pocketed rewards valued at 100 SGD (about $78, or 62 euros).

More than 35 years after Singapore introduced the world's first urban congestion pricing scheme—charging a fee to drive within the gridlocked city center-Prabhakar's projects on either side of the Pacific represent just two of the latest examples of a different approach.

Dutch Rewards

"Incentive is not a new technique in the field of travel demand management," said Chanyoung Lee, a senior research associate at the University of South Florida's Center for Urban Transportation Research.

For example, in the Netherlands, a rewards program called Spitsmijden (the Dutch word for avoiding peak traffic) traces its roots back to 2005, when a group of private companies, government agencies, and universities began organizing incentives for commuters to avoid the morning crunch time on Holland's heavily congested A12 highway between Zoetermeer and The Hague—a 15-kilometer (10-mile) stretch that can take less than 20 minutes without traffic.

Beginning in late 2006, Spitsmijden organizers used electronic devices installed in the cars of 340 recruits to log travel along the roadway. By riding a bike, taking public transport, shifting their morning drive before 7:30 a.m. or after 9:30 a.m., taking alternate routes to The Hague, or working from home, Spitsmijden commuters could earn cash or a Yeti smartphone.

Official results show that over a 10-week period, the number of rush-hour trips taken by this group of drivers along the A12 was cut in half, with most commuters still driving but shifting the trip earlier. For cash recipients, total earnings ranged from 27 euros to 290 euros (about $34 to $365), with individual rewards averaging 5 euros (about $6) per trip.

The Netherlands has implemented similar Spitsmijden experiments over the past four years. Commuters in the two most recent pilots, begun in September 2010 and 2011, can earn rewards through next month. After that, the cash incentives end and officials will analyze the results.

In a time of tight budgets for transport agencies, the raffle-like approach devised for Singapore and Stanford may deliver more bang for the buck than straightforward rewards programs like those in the Netherlands. The idea is that small amounts of money bundled into a few fat prizes can lure more people to change their behavior than guaranteed rewards of only a few dollars per trip ever could.

Yet precisely how people tend to react to different incentive schemes is not very well understood, Lee said. "People do care about incentive, but the increase in [reward] amount does not produce a linear increase of positive response." In other words, greater rewards do not necessarily translate to more people shifting their commutes. So the question of how to make financial incentives more cost-effective is the subject of Lee's latest study. She expects to deliver results next summer.

Already, it's clear that the technology available to traffic managers—notably, increasingly widespread mobile access to a social web—has come a long way since the first Spitsmijden trial. "Smartphones increase a participant's engagement with the program since there are more times for them to check the status of their friends and family," Prabhakar said. "We have found such social nudges to create a very positive feeling about change in participants, making them change their behavior more readily.

The six-month pilot project in Singapore is scheduled to end on July 9, and discussions are under way to expand the program island-wide. At Stanford, plans are in the works to add a parking component in the fall. Eventually, the school will start offering incentives for biking as well—possibly as early as next autumn, when a fresh cohort of commuters will arrive. who, with the right incentives, just might be game to change their travel habits.