Uber’s self-driving cars today resumed testing in autonomous mode on the streets of San Francisco. This comes two years after Uber’s self-driving cars were taken off the roads due to an accident that killed a pedestrian in Tempe, Arizona.

Two Uber self-driving cars, which are retrofitted Volvo XC90s, will roam San Francisco’s roads for the next few weeks. Uber said it will only test during daylight, and a safety driver and co-pilot will be present in each vehicle. The cars will operate in self-driving mode only in the Richmond District, which is on San Francisco’s less-crowded West Side. Uber’s human drivers will drive the vehicles in other parts of the city and on San Francisco highways.

“We are excited to resume autonomous testing in Uber’s home city this week,” said an Uber spokesperson in a statement. “Our testing area will be limited in scope to start, but we look forward to scaling up our efforts in the months ahead and learning from the difficult but informative road conditions that the Bay Area has to offer.”

Uber’s self-driving cars were granted permission to test in California last month. Uber’s self-driving cars are also being tested in autonomous mode in Pittsburgh. Uber is also testing in Dallas, Toronto and Washington DC, but human drivers operate the vehicles at all times.

Uber has been quite cautious since the fatal crash in 2018. The vehicle’s lone safety driver wasn’t watching the road when the car hit and killed 49-year-old Elaine Herzberg, who was walking her bike across the street. Police later discovered the safety driver was streaming the TV show The Voice on her phone at the time of the crash.

In November 2019, the National Transportation Safety Board issued a scathing indictment to Uber, citing its “inadequate safety culture.” Uber’s automated driving system detected Herzberg 5.6 seconds before impact, but it “never accurately identified the object crossing the road as a pedestrian,” according to the NTSB.

The NTSB blamed the incident on all parties invovled – Uber, the safety driver, Herzberg, and the state of Arizona. Uber was eventually cleared of any criminal wrongdoing. It settled a lawsuit with Herzberg’s family for an undisclosed sum.

Since the fatal accident, Uber added additional safety features and a real-time driver monitoring system that sends an alert if it detects a safety driver isn’t paying full attention.

The disengagement reports from California’s Department of Motor Vehicles (DMV) might not be the best way to analyze the performance of self-driving cars. However, it is worth noting that in 2018 Uber had the worst-performing self-driving cars in California. It experienced a disengagement every 0.4 miles, according to the California DMV. Apple wasn’t much better with a disengagement every 1.1 miles. Since Uber pulled its self-driving cars off the road in March 2018, it was excluded from the 2019 disengagement reports.