RER C
The RER C line is the second-longest in the network, with over of route. RER C was created from an amalgamation and renovation of several old SNCF commuter lines unlike RER A and B which had newer sections owned and constructed by RATP. Each day, over 531 trains run on the RER C alone, and carries over 540,000 passengers daily, 150,000 passengers more than the entirety of the TGV network.