The RER lines, for Réseau Express Régional, are different from other train lines because they do not terminate in Paris, but cross the capital underground, allowing passengers to travel from one end of the region to the other with the same transport line. These 5 lines alone have more than 3 million users, they are either co-operated by the RATP and the SNCF (lines A and B) or operated by the SNCF alone (lines C, D and E).
A short history of the RER
The first RER line created in the 1970s is the current RER A. Crossing the Île-de-France from west to east over 109 km (including 26 underground), it is now the most important train line in Europe with regular peaks of more than 1.3 million passengers per day. At peak times, 640,000 passengers use it, which is more than the population of the city of Lyon! It should be noted that the second busiest line in Europe is also an RER line, since it is line B running between the North and South of Île-de-France, which regularly exceeds one million passengers per day.
The increase in attendance
The RER lines have to deal with a very strong growth in the number of passengers (+20% in the space of 10 years), which has led to a deterioration in service on many sections. To deal with this phenomenon, Île-de-France Mobilités, with the operators RATP, SNCF, SNCF Réseau, the State, the Île-de-France Region and local authorities, in permanent consultation with elected officials and passenger associations, has launched numerous investment programmes to offer Ile-de-France residents a quality of service that is up to standard.