Converting Commuters into Carpoolers

Lessons in carpooling incentives from a large field experiment with Waze

When a 30-minute commute extends to 40 or 50 minutes during rush hour, commuters often use a GPS app to get them home more quickly. Over 130 million drivers in the U.S. use Waze, a Google-owned app designed to reroute drivers when traffic has stalled, or when collisions and construction are blocking their route.

When driving to work alone, chances are that most—three quarters of the commuting population in the United States— will use the app. Meanwhile, in Canada, the number of solo drivers is an even higher 83%.

It's convenient and freeing to drive alone. It's also part of North American culture—just the way things are done. And it's why traffic completely freezes up on most major highways one third of the workday, effectively wasting people's time and keeping cars idling.

Congestion pricing policies, carpool lanes, and new light rail train or subway infrastructure are all expensive, long-term ways for governments to battle traffic. A simpler solution, focused on human behaviour more than infrastructure, is convincing people to carpool.

How to make this case to drivers is at the core of new research conducted by Maxime Cohen, Associate Professor of Retail Management and Operations Management at McGill University.

"Carpooling is a free option to reduce congestion," says Cohen. "It can save a lot of time for a lot of people, which has a huge impact on the economy, and it can have a reducing effect on greenhouse gas emissions."

Using a sample of 537,370 Waze users across four American states, his study is, to date, the largest field experiment designed to encourage commuters to carpool.

Co-authored with three Waze researchers, Michael-David Fiszer, Avia Ratzon, and Roy Sasson, the study compares which incentives work best to convince drivers to open their vehicles to other passengers.

In September 2019, Waze Carpool customers completed more than 550,000 rides globally and the company reports being on track to completing one million carpools globally by early 2020. The service is currently available in the United States, Brazil, Mexico, and Israel.

“Despite this uptake, further convincing people to carpool will depend on each case, and there will be multiple factors to take into consideration,” says Cohen.

Time is (more important than) money

Previous research into consumer behaviour failed to find a consensus on whether time or money serves as the best incentive for carpooling.

But Cohen and his co-authors have determined that time saved was the most attractive incentive to carpool for Waze users.

Drivers with longer distances to travel and those who began and ended their workdays later were more likely to take on carpoolers. In addition, explicitly mentioning the high-occupancy vehicle (HOV) lanes to these drivers made the case compelling enough for them to try out the app's carpooling function.

The researchers used Waze data to determine that close to two thirds of the 116 million American solo car drivers had similar commutes.

During most of June and a portion of July 2019, Waze users in regions of California, Washington, Massachusetts, and Georgia received a range of app notifications on Waze.

Money—in the form of a $10 first-time incentive—was not a deciding factor for a click. The researchers weren't surprised given that drivers are so used to freedom and privacy when driving their own cars.

"But saving time, on the other hand, was something people were actually very receptive to," Cohen says.

Carpoolers chose to take on other passengers for the sake of convenience, saving money, and saving time. But it appears that saving time was the most important factor for drivers who have access to HOV lanes.

Companies can encourage their employees to carpool

Carpooling has been around since the 1940s. It was a rationing tactic in America during times of need, such as World War II and the 1970s energy crisis. Since then, the number of carpooling commuters has declined and the potential benefits, like saving time and money, are often eclipsed by carpooling challenges, like riding with a stranger.

Waze Carpool is designed to work past those challenges and was conceived to allow partnerships with companies that encourage their workers to use its carpooling services.

Since Waze Carpool launched in the San Francisco Bay area in 2016 and began actively promoting its carpooling function there in 2018, it has partnered with companies including AMD, Santa Monica Proper Hotel, Old Navy, Samsung, and Amazon.

While an app can streamline the process of getting colleagues to commute together, companies have long been at the forefront of carpooling initiatives across North America. Company policies can emphasize the benefits of carpooling by providing incentives—especially if they want to foster a sense of community among their employees that extends beyond work.

"They can offer things like parking for carpoolers, gas reimbursements, paying the car insurance," says Cohen. "Or they can leave earlier than everyone else. There are so many ways."

Once a carpooler, always a carpooler

While it might take some creative encouragement to get there, carpooling behaviour remains constant once it takes hold. But just how much nudging needs to happen for the decision to be made and the behaviour to stick?

"Using Waze data, we see that retention is high in carpooling," says Cohen. "But it's hard to understand how we can trigger a user to try it. It's extremely important and critical to understand what the motivating factors are for people to try it."

While it depends on the country, the length of the commute, and if the person has more flexibility, the researchers determined that carpoolers choose to take on other passengers for several reasons: for the sake of convenience, saving money, and saving time. However, the number one motivator for drivers to carpool was saving time, for those who had access to HOV lanes.

Persuading someone to pick up a stranger in their car is one thing. Even harder is convincing that driver to leave their vehicle at home and to get into someone else's car.

That's just one of the next few steps in solving this transportation puzzle, explains Cohen. "How can we incentivize you? Can we pay a toll for you? Combine you with the right person to make it fun? It will depend on the situation and the people."

Maxime CohenMaxime Cohen

Associate Professor of Retail Management and Operations Management

More from Maxime

Based on the research: “Incentivizing Commuters to Carpool: A Large Field Experiment with Waze
Read in French: Le covoiturage, une option sous-utilisée
Article written by: Joseph Mathieu

Illustration by: John W. Tomac

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