In order for train travel to be safe the rails the trains ride on need to be of a certain quality. You don’t want the equivalent of a pot hole on rails. In order to maintain good tracks workers need to shut down the rail line and physically go out to the rails. This delays trains, and therefore travelers. Nordic Unmanned, a Norwegian company, has created the BG-300 drone which is designed to monitor rail quality without having to alter train schedules.
As it does so, it inspects the tracks utilizing cameras and “other sensors,” plus it can lubricate rail switches if required. Importantly, though, if it encounters any other rail traffic, it will autonomously fly up off the tracks in order to get out of the way until that traffic passes. It can also use this functionality to move from one track to another.
As a result, stretches of rail lines do not have to be closed to trains while inspections are being performed. Such is not the case with traditionally used inspection vehicles, such as trolleys or rail-wheel-equipped trucks.