Waymo is adding another four cities to its growing list of robotaxi rollouts. The company announced Wednesday it has begun testing its autonomous vehicles (with a safety monitor) in Philadelphia, and that it will start manual driving to collect data in Baltimore, St. Louis, and Pittsburgh.

Waymo did not offer a timeline for when it plans to launch commercial services in those locations, nor do we know whether the Alphabet-owned company will partner with other companies to operate robotaxis in each one. That has been the move in cities like Atlanta and Austin, for example, where Waymo has partnered with Uber to advance its robotaxi rollout.

But the new locations join a list of over 20 cities where the company is either offering rides, prepping a commercial launch, or testing. Waymo is also now offering rides on freeways in Los Angeles, Phoenix, and the San Francisco Bay Area. The company plans to be doing one million rides per week by the end of 2026.

Waymo has done all this while claiming to be operating at a level five times safer than humans, according to data the company recently released.

But the expansion has not come without its issues. The National Highway Traffic Safety Administration is investigating how the company’s vehicles operate near school buses, after a Waymo was filmed driving around a stopped bus in Atlanta in September.

This week, Austin news outlet KXAN published a report showing Waymo’s vehicles have driven past school buses that were in the process of unloading or loading children multiple times — including after Waymo claims to have shipped software updates to address the problem.