The train runs 7.3 kilometers from Keleti to Kelenföld train stations, with stops at II. János Pál papa tér, Rákóczi tér, Kálvin tér, Fővám tér, Szent Gellért tér, Móricz Zsigmond körtér (a stop this longtime resident of Budapest can say has been needed for some time), Újbuda-központ and Bikás Park.

After plans were put on hold in the early 2000s, financing was approved for the project in 2004. By 2010, all tunnel work (undertaken by a joint venture of Austria-based Strabag and France-based Vinci Construction) had been completed. Government statistics had put total costs of the project at HUF 452.5 billion as of mid-2012.