The world’s first driverless tram went for its first test ride in real traffic in Potsdam, Germany, the Guardian reports. The adapted Combino tram was developed by engineering firm Siemens.

All aboard: On Friday, the autonomous tram trundled along a six-kilometer bit of track around Potsdam, near Berlin. The tram traveled in real traffic but—just to make things a bit more exciting for the press, probably—here was a staged emergency halfway along the route, when a Siemens employee pushed a pram into its path. Luckily, the tram picked up on the obstacle and conducted an emergency stop.

How it works: Much like a driverless car, the train uses various radar, lidar, and camera sensors to detect its surroundings and react to trackside signals, bikes, cars—and runaway prams.

What next? It isn’t yet commercially viable, Siemens says, but is likely to contribute to the broader field of driverless technology.