The CMN, in turn, was one of several companies that merged in 1999 to form the Transports Régionaux Neuchâtelois [de] (TRN).

[3] The railway was built by the Ponts–Sagne–Chaux-de-Fonds Railway (French legal name: Chemin de fer Régional La Chaux-de-Fonds - Les Ponts-de-Martel, PSC) as a metre-gauge line and is just over 16 kilometres long.

The line leaves La Chaux-de-Fonds station (at 994 metres above sea level) on a steep gradient of 4.0 percent and reaches its high point of 1120 metres after passing through a tunnel in Reymond.

The same transporter wagon system was also shared by the Chemins de fer des Montagnes Neuchâteloises from 1966, which began the transport of standard-gauge railway wagons on the line to Les Ponts-de-Martel.

On 17 December 1888, the Jura–Bern–Luzern (JBL) company opened the direct line from Biel to La Chaux-de-Fonds through the Crosettes tunnel and the Renan–Le Convers connection was closed in 1895.