Work stopped in late 2020 after the Montreuil Administrative Court annulled part of the environmental authorisation for the project.
The French government is appealing against this decision but has since identified that approximately 80% of the project is unaffected by the ruling and has restarted work on these sections.
The CDG Express project involves construction of a new terminal at Paris Gare de l’Est, a tunnel from there to the existing Gare du Nord - Laon line, the modernisation of this line as far as Mitry, and a new section of line from Mitry to the airport.
The total cost of the project is €2bn, including €500m for the modernisation of the parallel RER Line B. The new line is expected to carry seven million passengers a year and is due to open on December 1 2025.