The Langenthal–Melchnau railway line is a metre-gauge line between Langenthal and St. Urban in Switzerland; it originally ran to Melchnau. It was built by the former Langenthal–Melchnau-Bahn. The line runs through the cantons of Bern and Lucerne and is now owned and operated by Aare Seeland mobil.

The Aare Seeland mobil AG based in Langenthal is a transport company in Switzerland. It was created in 1999 from the merger of Oberaargau Regional Transport, the Solothurn-Niederbipp Railway, the Biel-Täuffelen-Ins Railway and the Oberaargauische Automobilkurse.