Waymo, the Alphabet subsidiary developing self-driving vehicles and an autonomous ride-hailing service, has logged another milestone ahead of a critical launch later this year. The company's fleet of autonomous vehicles has now logged 10 million miles on public roads in real-world traffic.

"While we've made great strides thanks to these 10 million miles, the next 10 million will focus on turning our advanced technology into a service that people will use and love," Waymo CEO John Krafcik wrote in a blog posted Wednesday on the company's website.

By the end of the year, Waymo will have its self-driving minivans available for public use in the Phoenix area. This will be the first robotaxi service in the U.S. and will mark a major advance in the development of self-driving vehicles. Currently, about 400 preapproved early users are getting rides in self-driving Waymo minivans. Those rides are restricted to a small area in metropolitan Phoenix.

As Waymo prepares for the wider launch, Krafcik knows his company's autonomous vehicles need to provide a more comfortable and convenient ride, with even greater capability.

"Our engineers and scientists are applying advanced artificial intelligence and new in-house designed sensing systems to help us navigate complex weather conditions like heavy rain and snow, which are difficult even for human drivers," Krafcik said.

The public ride-hailing service will be watched closely. In recent weeks, some in the Phoenix area have complained about Waymo minivans stopping for too long at stop signs or struggling in certain traffic situations.

While Waymo is starting its robotaxi service with a small fleet of autonomous vehicles, the company an option to order another 62,000 modified Chrysler Pacifica Hybrid minivans and 20,000 Jaguar I-Pace electric SUVs to expand its fleet.

Correction: Waymo has an option to order 62,000 modified Chrysler Pacifica Hybrid minivans and 20,000 Jaguar I-Pace electric SUVs to expand its fleet. The company hopes to have its self-driving minivans available for public use in the Phoenix area by the end of this year. An earlier version, misstated the timing and incorrectly stated Waymo had ordered the vehicles.