If you live in Gothenburg, Sweden, a city in the southwest of the country with a population of about 570,000, and drive to work or school, the regional transit agency wants to give you a two-week free pass to use on buses, ferries, and trams. It’s a program that the agency uses to tempt drivers out of cars—and it says that it’s working.

Since 2010, the agency, called Västtrafik, has launched nearly 30 of the “test ride” campaigns in western Sweden. Whenever someone moves to the area, they’re offered one of the temporary passes. Once or twice a year, the agency also runs large outreach campaigns, mailing letters to households in neighborhoods where car ownership is high, launching social media campaigns, and putting up ads on billboards and the backs of buses, inviting commuters to participate. Nearly half a million people have tried the passes, and that led to 100,000 new customers.

In an ad campaign this fall, the Sweden-based creative agency Forsman & Bodenfors assembled 30,000 toy cars to help residents visualize the impact of the campaign—which offered 30,000 free passes—on local traffic.

The free transit passes are only one part of the reason that people are willing to switch, says Joakim Gustafsson, a project manager at Västtrafik. “The number one decisive reason for the increase in travel is a conscious investment in more vehicles, more lines, and increased frequency,” he wrote in an email. In a country where the teenage climate activist Greta Thunberg helped spark the concept of “flight shame” to reduce greenhouse gas emissions, people are also increasingly willing to act for the environment. But the free passes can help commuters who might have already been considering a change take the next step.

“It’s always a challenge to make people break patterns,” says Gustafsson, noting that for people in certain parts of the region or with unusual hours, public transit may still not be convenient enough. “But as the public transport is expanded, we enable more and more people to evaluate public transport. And we think our ‘test ride’ concept fits perfectly as a constant reminder.” Other cities and countries have gone even further: Luxembourg, which has bad traffic, plans to make all public transit permanently free beginning next year.