We have been informed by SNCF that the RER line A which takes you to Cergy from Paris will be closed this summer from: 

August 5th to August 20th 2023. 

It can therefore be complicated to come to Cergy by the RER train during this period and it would be best to avoid completely the Paris area. Therefore we strongly recommend you to take the bus directly from the Charles de Gaulle airport. You can take bus line 95-18 for 2.5€ (please bring the exact amount since the driver cannot give you the change) and approximately 1 hour later, you are in Cergy-Préfecture which is about a 5-minute walk from the campus. The bus runs regularly from 5:20 am to 11:00 pm during the week and from 6:21 am to 9:21 pm during the weekend.  You can find the full schedule in the pdf attached which is valid from July 10th to September 3rd 2023.  

How to find the bus station and the bus at the airport?  Please go to Terminal 3 and to the Roissypôle bus station, Platform G1: