Privileged transit traffic or corridor traffic is traffic of one country across the territory of another country without usual customs and passport checks. The corresponding line of communication is called the (privileged) traffic corridor and a train used in this kind of transit is called a corridor train. The reason for such arrangements is usually border changes or border creation which cut through an existing transport corridor.

The Transalpin is a EuroCity express train linking Zürich (Switzerland) with Graz (Austria) via Liechtenstein. Introduced in 2013, it is operated by the Austrian Federal Railways (ÖBB) and the Swiss Federal Railways (SBB-CFF-FFS). From 1958 to 2010 a train of the same name linked Basel or Zürich with Vienna.