Paris RER-B Train to CDG

When boarding the RER B, or the RER A, trains which can have differing destinations departing from the same platforms, there is signage displaying both endpoints and en route stops for the next departing train. Not all northbound RER B departures go to CDG, as you point out, some trains go to Mitry Claye. Even within a given destination, not all trains make all potential en route stops.

Signage will provide you with all pertinent information.

@Doogie

Like Tocard has pointed out, the signage/monitor at the station is your best friend. This article explains how to read the signage; the photo is the signage for RER B from CDG to Paris city center; but the idea is similar for the other direction. https://francetravelplanner.com/go/paris/trans/air/choose_train.html

Starting after around 9 a.m. or so; they start to run both the regular train and the express train; the express train has less stops so it's much faster and less crowded. So make sure to get on the express train if it's running; you can identify it by looking at the 4-letter route code.

The fastest trains from CDG to central Paris have route codes beginning with KA (KALE, KALI, KAPE, KARE, etc.) or JA (JAMI, JANO), or UL. Other trains make more stops. (For your return to CDG airport from central Paris, look for train route codes beginning with E, because all trains beginning with E go to CDG. The express trains are ERIC, EROC, ERUK, ERIO, ERSE, EDME OR EDDY.)

Note that the destination station can vary from train to train; some train go farther than others. You can refer to the RER-B route map to determine which direction the train is heading to. But like the article pointed out the initial two letters of the 4-letter route code will tell you which direction the train is heading (to CDG, or to Paris city center) and if it's express train.

Currently RER B is undergoing a multi-year modernisation and maintenance works until 2025. Some of these works will require partial line interruptions, particularly during evenings and weekends; so you will want to plan ahead. I recommend that you install 'Bonjour RATP' app; which you can use to find out the train arrival times, route code and service interruptions.

Just to clarify, the train that takes you to your destination the fastest is the next train, be it express or otherwise. Express trains do not pass non-express trains. If the next available train is not an express, and you decide to wait for an express, you simply arrive much later than need be.

Exactly. And there aren't that many express trains. If you get lucky and catch one, great. But I would say I catch one maybe one out of 10 times. Hardly ever.

@Tocard: Good point!

Google maps is also a good way to search for train schedule; and if you click 'Detail' of a train you can find out if it has just a few stops or a dozen stops.

According to Google Maps for the June schedule the express train is running about every 15 mins (after about 9 am); regular & express are running alternatively. The express train will save you maybe 3 to 5 mins only (so it's not that fast); the main benefit is probably a less crowded train since it stops in just a few stations.

this is one of those things that once you KNOW that the B goes to two place, you can easily identify which train you need given all the signage etc. We made the mistake probably 25 years ago the first time we took the B to CDG from Paris -- I noticed that almost no one had luggage and so asked someone 'CDG?' and she said 'NON'. and directed us to get off and take the next train. We noticed luckily before the split and were fine. Once you know it is trivial to get the right train.

@ janettravels44

I noticed that almost no one had luggage

Actually this is a great way to tell if the train is going to CDG! I have to keep this in mind :)