The RER and Transilien networks are Paris’ suburban train systems. RER Line A is the busiest train line in all of Europe with a daily ridership of 1.2 millions riders on that line alone. The different RER lines travel straight across the center of Paris undeground making it convenient to travel inside Paris. What is the RER & Transilien (and what’s the difference)? The RER is a mix of both rapid transit and regional rail. It operates quite frequently, but still slightly less frequently than a regular métro system and often uses double decker trains. The RER also travels across the center of Paris underground making several stops in the city. Transilien is more a true commuter rail system where trains terminate in a major railway station often with trains operating every hour. How To Ride Get to a station: Look for the RER in a circle logo for an RER station, or the M in a circle for a métro station. A sign outside the station tells you the station name and what lines go there. P
Métro, RER, Buses, & Trams