My wife is travelling to Strasbourg on August 28 and has to get from CDG to the Gare de l'Est.
I've looked at three different travel guides and found that the RATP Bus # 350 does this direct route, but it can take over an hour, plus she is arriving during rush hour and has to make the TGV departure I hae to book as well.
The Lonely Planet guide is the best, but all it says is that the RER B 3 line runs "to the city."
What I still can't figure out yet is how close it run to the Gare de l'Est.
If it doesn;t go to the Gare de l'Est, where would she take the RER B 3 train to in order to transfer to another train or Metro to get to the gare de l'Est.


Take the RER B to Gare du Nord. Walk to Gare de l'Est (about ten minutes). Or transfer to either Metro line 4 (direction Porte d'Orleans) or Metro line 5 (direction Place d'Italie) and take it one stop to Gare de l'Est. Follow the "correspondance" (transfer) signs to find your way through the tunnels from the RER B line to either Metro line 4 or 5. The fare is €8.20.
Go to www.ratp.fr and click on the British flag in the lower left-hand corner. Download and print a Metro/RER map for central Paris and a RER map that show service to outlying zones, including CDG.

I forgot to give you the travel time. Whether your wife transfers or walks from Gare du Nord to Gare de l'Est, the whole trip will take about 45 minutes.
Gare de l'Est is just 400 meters from Gare du Nord. The last section is a flight of old steps that are seen in just about every French WW2 movie.

Thank you very much Timothy, from myself and my wife. She specifically asked me to say thank you.
Now onemore dumb quesiton.
In the Lonely Planet guide it says the same RATP tockets are valdi onthe metro, the RER, buses and tram lines.
I'm still uncertain however if she would have to buy a metro ticket to go that one stop or if that RER ticket is valid on the metro.

hublocker, tell your wife that she is most welcome!
The ticket she will buy for the RER from CDG to central Paris (€8.20) is good for unlimited transfers to other RER lines and/or Metro lines so long as she doesn't exit the system.

Just to add to Timothy's comments: The time from boarding the RER train at CDG to arriving by Métro at the Gare de l'Est may be as little as 45 minutes, but you'd want to allow extra time for confusion while transferring from the RER to the Métro. Also, I'd want to arrive at the Gare de l'Est at least 30 minutes before the TGV's departure, to allow plenty of time to find the right platform, coach and seat. And this may go without saying, but it could be an hour from the time she steps off the aircraft to the time she walks out of the customs area with her luggage (my average has been 45 minutes).
I wouldn't be comfortable unless I allowed three hours between the plane's scheduled landing and the TGV's scheduled departure. Finally, I'd think twice before buying a highly discounted train ticket such as the "Prem's" fare. If she misses her intended train, she can take a later tain with a full-fare ticket, but a "Prem's" ticket is useless and non-refundable.
-- Steve

Yeah,
We had planned on about that, 3 hours Steve.
What is the difference between full fare and the "Prem" ticket?

>> What is the difference between full fare and the "Prem" ticket? <<
For a second-class ticket from Paris to Strasbourg on August 28, the full fare is € 63, and the Prem's fare is € 35 - and the first-class Prem's fare is € 45. Quite a big discount. But you really need to be sure of catching the particular train. Schedules and fares are at sncf.com.