Hitachi says there will be no need to remove the phone from pockets and bags, and the app will calculate the correct fare for the journey.

The technology will initially be tested with Trentino Transport in Trento, Italy.

“We are now beginning to test this technology and looking at the possibility of one app working across large stretches of a country,” says Hitachi Rail managing director, Ms Karen Boswell. “For example, a passenger could use the app to take a bus in their local town and a train elsewhere in the country all in one day.”

Hitachi says results from the proof-of-concept tests in Italy will help inform the best ways to apply the technology in future.