DETROIT (AP) — General Motors’ Cruise autonomous vehicle unit is backing off plans to start a self-driving ride service by the end of this year, with its CEO saying more time is needed to make sure it runs safely.

Cruise CEO Dan Ammann, in a blog post on Wednesday, said the company still plans to deploy the service in the city of San Francisco. Asked for more specific timing, he said through a spokesman: “As soon as possible.”

In November of 2017, GM revealed at an investor event that it planned to start carrying passengers and delivering goods without human backup drivers by the end of 2019. Executives didn’t say how many vehicles would be deployed, but said that it was important to be ahead of other automakers and tech companies.

But the company has hinted of late that it wouldn’t hit the 2019 timeframe, saying deployment would be “gated by safety.”

“In order to reach the level of performance and safety validation required to deploy a fully driverless service in San Francisco, we will be significantly increasing our testing and validation miles over the balance of the year,” Ammann wrote in the blog. “Which has the effect of carrying the timing of fully driverless deployment beyond the end of the year.”

The delay comes just over a year after a self-driving Uber test SUV ran down and killed a woman in March of 2018 in the Phoenix suburb of Tempe, Arizona. Until the crash, autonomous vehicle development was rushing headlong toward deployment on public roads, but it forced companies to slow down and evaluate the safety of their systems. The crash also eroded public trust in the systems, which tech and auto companies are trying to rebuild.

Ammann said in the blog that Cruise will work with the San Francisco community to demonstrate its cars’ capabilities and make sure people trust the company’s technology.

“There is clearly a reckoning happening today around ‘Big Tech’ and Silicon Valley,” Ammann wrote. “We’ve seen what happens when transformative technologies are deployed without deep engagement with and consideration for the community.”

Google autonomous vehicle spinoff Waymo had once pledged to run a self-driving ride service without human backups in the Phoenix area by the end of 2018, but the company also has delayed its debut. Although Waymo has tested full self-driving vans on public roads, it delayed a large-scale service indefinitely.

Electric car maker Tesla is still giving a date for deployment of vehicles that can fully drive themselves without human intervention. In April, CEO Elon Musk said he expects to start converting the company’s electric cars into fully self-driving vehicles next year as part of an audacious plan to create a network of robotic taxis. But critics are skeptical that he has the technology to pull it off safely.

Musk touted Tesla’s superior computer power and data-gathering as a better way of making self-driving cars than virtually every other of the more than 60 companies in the U.S. working toward the same goal.

Ammann wrote that Cruise is well on its way toward having the building blocks needed to send out the self-driving cars. The company, which has attracted more than $7 billion in investment from Japan’s SoftBank, Honda, T. Rowe Price and others, has grown during the past four years from 40 employees to about 1,500 as it tests fully autonomous Chevrolet Bolt electric cars.

Shares of GM rose slightly in morning trading Wednesday to $40.80.

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