Paris is served by a network of commuter express trains, running on five different routes within the city and its suburbs. The Reseau Express Regional (RER) connects the city's underground metro system with its suburban commuter raili links. The RER offers a number of interchanges with the metro system and major stations, but offers a service with fewer stops, thereby acting as more of an express system.
In total, the RER network includes 246 stations, with nearly 600km of track. Its five lines are simply named Line A to Line E.
If you are travelling on the RER within Paris' Zone 1 area, you can use a standard metro ticket for your journey. Beyond this area, passengers require a Billet Ile de France. Ticket prices vary depending on the distance travelled (for journeys outside Zone 1), and tickets can be bought from any RER or metro station. Longer length passes are also available, for travel over the day, number of days or week.
There is only Standard Class accommodation on RER services. Some trains are single deck, whilst most are double-deck. Seats are well-worn, but perfectly comfortable.
RER trains can be very busy during rush hour. When getting on or off the train, you will probably need to open the train doors manually using the button by the door handle.
Luggage & Facilities
There are no limits on the amount of luggage passengers can take on-board RER services, but during rush hour when services are busy, you might not be too popular if you have a lot of items with you.
RER services are generally better equipped than Paris' metro system for disabled passengers. The gap between trains and platforms tends to be quite large however, and there tends to be a step up/down between them. RER Line E is the only RER line with roll-on/off access for wheelchairs. Most stations are wheelchair accessible however.
Travelling with Pets
Small dogs can be taken on RER services free of charge. Larger dogs can be taken provided they are on a lead and muzzled, although you should buy a ticket for them (half price - known as "demi tarif").