Uber started tracking its drivers in China through GPS coordinates around six months ago. At the time it was designed to track whether any drivers were attending protests in the city of Hangzhou, located in Eastern China. While that appeared to be an isolated incident, Uber has recently quietly started monitoring some of its drivers as part of a new pilot program.

It's designed to respond to customer complaints about speeding or drivers braking too hard. "Gyrometers in phones can measure small movements, while GPS and accelerometers show how often a vehicle starts and stops, as well as its overall speed," explains Joe Sullivan, Uber's chief security officer. "If a rider complains that a driver accelerated too fast and broke too hard, we can review that trip using data."

Uber will also use the data to improve passenger safety

Uber is also planning to use its data captures to "improve safety proactively." The company cites an example of drivers moving their phones around too often, noting that Uber "can offer them mounts to fix the problem." If drivers are speeding regularly then Uber can "ask them to curb their enthusiasm," according to Sullivan.

The safety implications for passengers are encouraging, but Uber's monitoring of drivers will undoubtedly generate complaints from the drivers themselves. A class action lawsuit challenging the way Uber classifies its drivers as independent contractors is due to start in June, and the case could change how much control Uber has over its drivers' working conditions.