A small group of residents in Singapore can now hail self-driving taxis with their smartphones, in the world’s first public trial of autonomous driving technology.

While billed as a pioneering trial, the service covers a relatively small area and its riders will be hand-picked. Invited members of the public can summon a car from a fleet of six reconfigured Renault Zoes and Mitsubishi i-MiEVs to ferry them within a 500-acre research and high-tech business park. An engineer from the company will ride in vehicles to monitor performance and take the wheel if required, according to a release from Singapore-based start-up nuTonomy.

NuTonomy runs one of several autonomous driving projects in the island nation, which is promoting the technology as part of efforts to reduce a reliance on privately owned cars. Public transit operator SMRT Corp. set up a joint venture in April with a Netherlands-based company to operate “driverless pods.”

A center for testing and research of autonomous vehicles was set up this month by the land transport authority and one of its universities.

“The technology is maturing to a point where commercial services are becoming possible once you’re able to prove the reliability and safety,” said Doug Parker, chief operating officer of nuTonomy. “I would say it’ll happen sooner rather than later,” with fully autonomous cars that run without safety drivers possible in five years, he said.

Self-driving taxis came into focus after Uber Technologies Inc. said it will soon allow customers in downtown Pittsburgh to summon autonomous cars with their phones. Like nuTonomy’s trial, that fleet of specially modified Volvo XC90 SUVs will be supervised by humans in the driver’s seat.

nuTonomy, which has raised about $20 million from mostly U.S. investors, doesn’t have plans for an initial public offering for now, Parker said. The company plans to attract investors from other countries in future rounds of financing and expand the research and development team.

The company is in talks with three other countries in Asia, as well as some cities in the U.S. and the United Kingdom, about holding similar autonomous driving trials, Parker said. He declined to name the locations.