In this article, Lonely Planet takes a look at the sustainability of five popular European routes, comparing cost, journey time and emissions, to help you choose your preferred mode of transport. Unsurprisingly perhaps, the train option comes out top from an environmental perspective for all journeys. In the wake of the recent ruling that Heathrow’s proposed third runway is in fact illegaldue to the lack of environmental considerations to date, rail is continuing to pull ahead as the suatainable travel mode of choice.