Eole project at the CNIT La Défense train station

As part of Eole, the project to extend line E of the RER rail network to the west, VINCI Construction Grands Projets, a member of the consortium led by VINCI Construction France, is taking part in the construction of a new train station under the CNIT dome, along with tunnels measuring a kilometre long, a shaft 40 metres deep and 15 metres in diameter, and several underground walkways connecting line E to line A of the RER, to lines L and U of the Île-de-France suburban rail network, and line T2 of the Tramway system.


Extending line E of the RER rail network, which was recognised as a project of public utility on January 31, 2013, is designed to strengthen east-west connections in the Île-de-France region through better-quality service. The project will have an impact on 620,000 passengers. Line E will be extended by 55 kilometres to the west, including 8 kilometres in a tunnel, from Haussmann Saint-Lazare to Mantes-la-Jolie train stations. A total of 47 kilometres of existing rail lines will be redeveloped and three new stations will be built at Porte Maillot, La Défense-CNIT, and Nanterre-la-Folie. Entry into service will occur in stages, including Nanterre in 2022 and Mantes-la-Jolie in 2024.

Technical overview

On this project our challenge was to build an 18,000-square-metre train station 20 metres underground that provides quick and easy interconnections in what is France’s busiest multimodal rail hub (including connections to other transport systems) as well as convenient access to the esplanade at La Défense. The project calls for the redevelopment of CNIT (the centre for new industries and technologies), including adding 7,000 square metres of retail space.
To meet a key project objective, our teams will have to deploy solutions that minimise noise pollution at the site and on the floors above the worksite. That is why an “acoustic sarcophagus” (including the floor, walls, and ceiling) encloses the worksite below CNIT.
The project comprises several operations: strengthening the foundations at CNIT, which will be placed “in suspension” while its 124 piles are reinforced; building the main structure of the train station; developing connections to public transport networks and CNIT; creating various exits for line E of the RER; ensuring access to users with reduced mobility (lifts, platforms, ramps, slip-resistant passageways, and tactile bands).
In late 2015, initial construction operations in the train station began with the re-routing of utility networks servicing CNIT. Later, an opening was created several levels below CNIT to facilitate project logistics. Subsequently, this space will accommodate escalators, staircases, and lifts, linking the station to CNIT. Later still, the foundations of the car park under CNIT will be reinforced, and a foundation slab under which the train station will be built will be implemented.
The last stage of the project consists in excavation and the creation of the various structures of the train station through works to be carried out during day and night shifts in 2018. Final development tasks will get under way in 2019.

This major project must overcome a technical challenge, namely, to build a new underground train station without disrupting activities in the busiest business district in France with 500,000 users a day.


The project to extend line E of the RER is part of an ambitious undertaking to develop and modernise transport infrastructure in the Île-de-France region – this major initiative is known as “Nouveau Grand Paris.” It will facilitate access to employment hubs, improve connections between current centres of economic activity, and foster the development of residential districts. As a result, the regions of La Défense and Seine Aval will be better served.
The project also aims to improve service quality on public transport networks in the Île-de-France region, including relieving congestion on line A of the RER (the busiest urban rail line in Europe), easing overall transport connections, reducing travel time on many sections, and renovating existing infrastructure. Consequently, the business district at La Défense will see its power of attraction increase.

Project participants

SNCF Réseau

Project management

Key figures

Implementation dates
July 2016 to August 2021

18,000 square-metre train station

Depth of the shaft
40 metres

7,000 square metres of new retail space

More information


(Vidéo : “Les dessous du prolongement du RER E sous le CNIT à La Défense”)