Hi, I love your information, but I needed to know if possible the best simplest route to take travelling with children, please can I have your opinion. I was given this by the hotel below and I still have no idea?
- RER B in the direction of “SAINT REMY LES CHEVREUSES” and descend at Châtelet-Les-Halles ;
- RER A in the direction of either “POISSY” or “CERGY-LE-HAUT” and descend at Maisons-Laffitte;
- From the RER A station of Maisons-Laffitte it is approximately a 10 minute walk downhill.
The ride from the Airport to Chatelet can vary from 20 minutes to 50, depending on if you catch an express train or not. From Châtelet to Maisons-Laffitte is just under 30 minutes.
Those directions are correct and may seem a bit overwhelming at first, but it'll be fine.
When you're taking the RER B train from CDG Airport terminal 2 train station to Paris, you cannot take the wrong train since all trains are heading towards Paris and all will stop at Chatelet les Halles station. CDG Terminal 2 is the terminus end of RER B trains so it's impossible to catch it in the wrong direction from CDG T2. Thus, you can ignore the information about Saint Remy les Chevreuses. Any train from CDG T2 is fine/will take you to Chatelet les Halles.
Chatelet les Halles is a large interchange in the heart of Paris and changing trains here may seem daunting at first, but the colors of the RER lines will help ease the transfer.
When you arrive at Chatelet les Halles and step off the RER B line, you'll see that there are several train platforms at this level. The platform you'll alight onto is shared (if I remember correctly) with an RER A train which will stop on the opposite side of this platform you are standing on. My memory is fuzzy on this (or things may have changed), but I believe the RER A train on this platform is heading in the opposite direction to what you need (i.e. towards Marne la Vallée/Disneyland, not towards Poissy/Cergy-le-Haut).
Please check the overhead panels along this platform which will show all the stations served by the next train and will look like this. If you don't see Poissy as the last station on the panel this is the wrong platform & you'll need to transfer to the right RER A platform, which means you'll need to look for RER A signs overhead and near stairs/escalators (look for a Red circled "A" denoting the RER A train line) and climb some stairs / ride an escalator.
The RER A train line heading westbound has three branches & therefore three different terminus stations: Saint-Germain-en-Laye, Poissy, and Cergy-le-Haut. Maisons-Laffitte station is serviced by RER A trains heading towards either Poissy or Cergy-le-Haut, but not Saint-Germain-en-Laye. When you're on the correct (westbound) RER A platform, the overhead panel will show all stations along the line with a light lit beside the stations that the next train will stop at. You'll want to board a RER A train when the Maisons-Laffitte station is "lit" on this panel (unlike in the linked photo).
On board the RER train, above the doors will be a line map showing all stations along the line. The stations that will be served will be lit by a little light. You can double check you're on the right train by verifying Maisons-Laffitte station is "lit". Once a station has been served, the light is extinguished on the line map.
Make sure you hang onto your RER ticket you purchased at CDG Airport train station. You'll likely need to use that ticket in the fare gate at Maisons-Laffitte to open & exit the fare-paid area and make your way to the street.
I hope this gives you a better idea of the transfer you'll make at Chatelet les Halles. I believe you'll have no problems getting the Maisons-Laffitte. Feel free to post another question if you have further queries.