The RER E western extension will link the Haussmann Saint-Lazare station to Mantes-la-Jolie via La Défense and Poissy. The execution of this project is required for several reasons: reduce congestion on the RER A line, improve accessibility to Seine–Aval as well as access to the Gare du Nord, Gare de l’Est and Charles de Gaulle airport stations.



These new underground infrastructures were subject to preliminary studies carried out by setec tpi in 2010 and 2011.





The services provided by the consortium include the design studies and works project management (preliminary design, working design, client assistance, construction management and supervision, assistance during acceptance operations) for the structural works, non-structural trades, electromechanical equipment and low voltage equipment for the track and catenary between the rear of the Haussmann St Lazare station and the Nanterre-La Folie station.

Key information


Client : SNCF Réseau

Design Joint Venture : setec (lead contractor) – Egis Rail – Agence JM Duthilleul

Period  : 2012-2022

©Anne-Claude Barbier pour setec tpi

In a Nutshell

8km of tunnel
Considerable constraints of existing works


The project is characterised by the considerable extent of the interfaces with regards to third party project managers and clients as well as the proximity of existing works.

The CNIT station is located under the CNIT vault. Its structure comprises a thin shell recessed into three enormous abutments interconnected by ties. The construction lies within an equilateral triangle with 218m long sides.

Given its exceptional nature, 3D simulations were carried out to analyse the effects of any movements caused by the works.