The C-4 is a line and rail service of Cercanías Madrid commuter rail network, operated by Renfe Operadora. It runs from Parla to Alcobendas (Alcobendas – San Sebastián de los Reyes station) and Colmenar Viejo. It crosses a total distance of 62.2 kilometers.
References
C-4 (Cercanías Madrid) Wikipedia(Text) CC BY-SA