Réseau Express Régional

French transit system in the Paris region

The Réseau Express Régional, commonly abbreviated RER, is a hybrid commuter rail and rapid transit system, similar to the S-Bahns of German-speaking countries and the S Lines of Milan, serving Paris and its suburbs. It acts as a combined city-center underground rail system and suburbs-to-city-center commuter rail. In the city center, it acts as a faster counterpart of the Paris Métro, having fewer stops.

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