The world's first self-driving taxis will be picking up passengers in Singapore starting Thursday.

Select members of the public will be able to hail a free ride through their smartphones in taxis operated by nuTonomy, a US-based autonomous vehicle software startup that has been conducting trials of self-driving vehicles in Singapore since April.

The company says it will be the first to offer rides to the public. It will beat ride-hailing service Uber, which plans to offer rides in autonomous cars in Pittsburgh, by a few weeks.

nuTonomy's service will start small - six cars now, growing to a dozen by the end of the year. The ultimate goal, say nuTonomy officials, is to have a fully self-driving taxi fleet in Singapore by 2018, which will help to sharply cut the number of cars on Singapore's congested roads.

For now, the taxis will only run in a 2.5-square-mile business and residential district called "one-north," and pick-ups and drop-offs will be limited to specified locations. The trials will take place under normal traffic conditions and include both light and heavy traffic routes. And riders must have an invitation from nuTonomy to use the service.

The company says dozens have signed up for the launch, and it plans to expand that list to thousands of people within a few months.

nuTonomy is using specially configured Renault Zoe and Mitsubishi i-MiEV electric vehicles for the trials, and they will have a driver in front who is prepared to take control of the vehicle if necessary and a researcher in the back to watch the car's computers.

Not alone

The testing time-frame is open-ended, said nuTonomy CEO Karl Iagnemma. Eventually, riders may start paying for the service, and more pick-up and drop-off points will be added.

NuTonomy also is working on testing similar taxi services in other Asian cities as well as in the US and Europe, but he wouldn't say when. "I don't expect there to be a time where we say, 'We've learned enough,'" Iagnemma said.

However, it's not the only firm that is looking at ways to promote autonomous driving. Companies like Tesla and Google have been pouring massive investments into autonomous-vehicle technology and striving to come up with a viable self-driving car.

But a large number of safety and legal issues have dogged their efforts. Google's self-driving cars, for instance, have been involved in nearly a dozen collisions in or around Mountain View since starting to test on city streets in the spring of 2014.

Tesla also received a lot of attention worldwide this year when one of its self-driving automobiles was involved in a fatal accident.

It also remains unclear what kind of legal changes have to be made for autonomous driving to become more commonplace.

sri/hg (AP)