Paris–Saint-Germain-en-Laye railway

The Paris–Saint-Lazare–Saint-Germain-en-Laye line is a 20.4 km (12.7 mi) long double-track suburban railway line in France, connecting Paris-Saint-Lazare station (8th arrondissement of Paris) to Saint-Germain-en-Laye station, in the Yvelines department. It is now designated as line no. 975 000 of the national rail network.

Inaugurated in 1837 between Paris and Le Pecq, it was the first railway line built from Paris, but also the first in France designed solely for passenger transport and operated using steam locomotives, five years after the opening between 1830 and 1832 of the Saint-Étienne–Lyon railway, built by the brothers Paul and Marc Seguin. Transport on this last line was intended for goods and passengers, and traction was entrusted to Seguin locomotives with tubular boilers. On the Saint-Étienne–Andrézieux railway, the first line built on the continent and opened in 1827, horse-drawn traction was initially used.

The Paris to Le Pecq line was modernised during the 1920s with third rail electrification and the introduction of Z 1300 ("Standard") trains. Its western half has been incorporated into RER line A since 1972 and is operated by the Régie autonome des transports parisiens (RATP). The rest of the line is operated by the Société nationale des chemins de fer français (SNCF) and forms a branch of Transilien Line L.