Online travel provider Expedia Inc. (EXPE) is looking to build up its rail booking services in the United States, Chief Executive Dara Khosrowshahi said in an interview with Reuters on Tuesday.

The Bellevue, Washington-based company, which offers online bookings of hotels, flights and cars for travelers, is working to expand those capabilities to passenger train service on a global basis, Khosrowshahi said, looking to key markets like Europe, where it has already started offering rail bookings in the United Kingdom and Germany.

“Rail in Europe is incredibly important as far as a transportation medium,” Khosrowshahi said in an interview. “It’s becoming increasingly important in the Asia-Pacific markets. And I think in the U.S., rail isn’t quite as strong, but we are certainly building up infrastructure on the back end to be able to expand our rail offering on a global basis.”

Plans for expanding its U.S. rail booking options are in the early stages, Khosrowshahi said, declining to provide further details.

In June, the company acquired a majority stake in SilverRail Technologies Inc, an unlisted retailing and distribution platform for rail, at an undisclosed price.

Although SilverRail is based in London, Expedia actually began partnering with the firm in 2010 for its corporate travel brand, Egencia, to provide rail options in the United States, where nearly all long-distance passenger train service is provided by U.S. government-owned Amtrak.

“With all the talk about being environmentally friendly, you know we do think it is a good way for people to get around, it’s a good transport mechanism and it’s one that we want to promote,” Khosrowshahi said.

Expedia shares, which are up over 29 percent over the past year, were trading at $147.61 after the market close on Tuesday.