Nearly two years after launching its ambitious self-driving chauffeur service in Pittsburgh, Uber is scaling back the operation due to concerns raised by a fatal crash earlier this year. The ride-sharing tech giant laid off dozens of autonomous vehicle monitors in the Steel City on Wednesday, Quartz reported.

Those affected by the layoffs were backup drivers whose job was to take the wheel in case the company’s autonomous vehicles were not up to the task at hand. Uber launched its self-driving fleet in Pittsburgh in September 2016 and expanded it to a few other markets afterward. According to Quartz’s report, Uber cut about 100 backup driver jobs in Pittsburgh during a company meeting on Wednesday.

The move came about four months after an autonomous Uber vehicle struck and killed a pedestrian in Tempe, Arizona. That was believed to be the first pedestrian death by a self-driving vehicle. The vehicle hit the woman as she was walking across a highway at night. There was a driver present in the car at the time, but a police investigation concluded they were distracted by streaming a television show on their phone when the collision occurred.

uber sefl Uber laid off its self-driving force in Pittsburgh. An Uber driverless Ford Fusion drives down Smallman Street on September, 22, 2016 in Pittsburgh, Pennsylvania. Photo: Jeff Swensen/Getty Images

Uber eventually shut down the self-driving fleet in Arizona, laying off around 300 people in the process, per Quartz. Autonomous vehicle operations were suspended in every other market in which Uber experimented with the idea, including Pittsburgh, Toronto, and San Francisco. Interestingly, Uber’s self-driving vehicle operators were hired as employees, rather than independent contractors like regular Uber drivers.

As Quartz pointed out, Uber launched its self-driving program in Pittsburgh and other cities with two operators per vehicle. Eventually, Uber scaled it back to just one operator per vehicle as a cost-cutting measure, with the eventual goal of getting humans out of the equation altogether.

The roughly 100 laid-off employees were given permission to apply to other positions within the company. Uber said it would replace them with a force of “mission specialists,” who will test self-driving vehicles and give technical feedback to developers. There will be 55 of these specialists, per Quartz’s report.

It has been a year of scandals for Uber. At the end of April, CNN found that there were more than 100 accusations of sexual misconduct against Uber drivers since 2014. On Tuesday, it was reported that Uber’s HR chief left the company following accusations that she had regularly waved off racist incidents within the company.