By 2023, French railway operator SNCF expects to debut prototypes of driverless mainline trains for both freight and passengers, according to a recent announcement, subsequently including them in scheduled services.

"With autonomous trains, all the trains will run in a harmonized way and at the same speed," SNCF chairman Guillaume Pepy said. "The train system will become more fluid."

SNCF’s objective with this scheme is to run more trains on France’s busiest lines while also cutting energy consumption.

Although driverless trains are nothing new to cities like Paris with driverless metro trains traversing that city, driverless long-distance trains will present an entirely new set of challenges.

"Railways are an open system, and the unexpected is the rule," Pepy said.

The shift, according to Pierre Izard, who runs SNCF's rail technologies division, is expected to happen in stages "up to the most extreme of automatisation, when there is no human presence onboard."