Air travelers in Canada, France, Germany and Spain may increasingly find that they are doing part of their journey on the ground, as airlines work with rail companies to sell tickets for combined trips.

William Agius, a lecturer at the Zurich University of Applied Sciences and a frequent traveler, said he had booked tickets on Air France, Lufthansa and Swiss that included legs by rail.

“During the booking process, you notice no difference, and at the end of the process you have a message alerting you to the fact that that particular service is operated by train and not by plane,” he said.

A combination of faster trains and slower progress through crowded airports makes rail travel competitive with air on routes that are three and a half to four and a half hours long, said Andrew Sharp, director general of the International Air Rail Organization, based in London. This is especially the case in Europe, where many railway stations are in or near international airports.