Don’t expect self-driving cars to become ubiquitous for a long time, a key Uber executive has said.

The ride-sharing company is getting ready to go public. Rival Lyft recently beat it to an IPO.

Raquel Urtasun, the chief scientist at Uber Advanced Technologies Group (ATG) who also runs the group’s unit in Toronto, told Reuters: “Self-driving cars are going to be in our lives.

“The question of when is not clear yet.

“To have it at scale is going to take a long time.”

The tone was more cautious and suggested a less aggressive approach since an Uber autonomous SUV killed a pedestrian in Tempe, Arizona, in March 2018.

Reuters noted the self-driving industry had tempered expectations and pushed out timelines for deployment. The extreme technical challenges of building cars that could predict human behaviour and respond appropriately had proved greater than anticipated.

Uber, whose losses before taxes, depreciation and other expenses were US$1.8bn last year, has at times spent close to $200m in a single quarter on its self-driving unit, sources told Reuters.

Uber, last valued at $76bn in the private market, is seeking a valuation as high as $120bn in its IPO and may kick off its investor roadshow before the end of April, Reuters has reported.

“It is true that when you go to an IPO, there is much more of a look into your finances,” Urtasun told the news agency.

“That being said, again because Uber understands that self-driving cars at scale is not something that’s going to happen tomorrow, they understand the need for the science.”

Urtasun declined to offer Reuters any guidance on what mix of human-driven cars and autonomous cars Uber would have in the next decade, citing too many uncertainties in the industry.

“What is clear is that in a 10-year timeframe there will be a mix of both (self-driving and human-controlled cars),” she said.