Almost half of the European Union's busiest international flight routes are difficult or impossible to book by train, according to a new report by the Transport & Environment (T&E) thinktank, which warns that an outdated ticketing system is undermining efforts to shift travellers away from polluting short-haul flights. Popular corridors such as Lisbon–Madrid and Barcelona–Milan cannot be booked through any rail operator's website, while dominant national carriers — such as Deutsche Bahn in Germany or SNCF in France — fail to sell competitors' tickets on 86% of routes where alternatives exist. The European Commission is expected to release a single ticketing package on 13 May that could address the fragmentation, which T&E says is preventing even climate-conscious travellers from choosing the greener option.