Réseau Express Régional

Suburban commuter rail network in the Paris region

The Réseau Express Régional (French pronunciation: [ʁezo ɛkspʁɛs ʁeʒjɔnal]; English: Regional Express Network), commonly abbreviated RER (pronounced [ɛʁəɛʁ]), is a hybrid commuter rail and rapid transit system serving the city centre of Paris and its suburbs. It functions as a combined city centre underground rail system and suburbs-to-city-centre commuter rail network, in a similar manner to the S-Bahn systems in Germany, Austria and Switzerland, S-train in Copenhagen, the Pendeltåg in Sweden, the Overground, Thameslink and Elizabeth Line in London, the Merseyrail in Liverpool, the S Lines in Milan, BART in the San Francisco Bay Area, and many other urban rail networks around the world. It is part of the network of transport services managed by Île-de-France Mobilités.

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