Borne says the decision to delay the CDG line from Paris Gare de l’Est to CDG Terminal 2 was taken to minimise the impact on commuters.

Trains will use the existing line between Paris Est and Villeparisis, before continuing northwards on a new 8km branch which will follow the alignment of TGV Interconnexion to the airport. The line was scheduled to open on December 31 2023 and the decision means that the project will not be ready in time for the 2024 Paris Olympic and Paralympic Games.

The project has caused controversy with residents and elected officials of Ile-de-France, especially in northern Paris, who argue that with 15 other construction projects planned in the region in the coming years, work will cause significant disruption to existing commuter services, in particular RER Line B.

CDG Express is expected to cost €1.8bn and Borne says the delay will add “a few tens” of millions of euros and a hundred maximum” to the cost of the project. For RER Line B users the result is likely to be more weekend disruption to services between 2021 and 2023.

The Hello Paris consortium of Keolis and RATP Dev secured the contract to operate the service in November 2018.

The journey will take 20 minutes and a one-way fare will cost €24. Up to nine million passengers a year are expected to use the service.

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