Grand Paris Express Project

The Grand Paris Express project

The Société du Grand Paris, a public company set up by the government, is in charge of the Grand Paris Express project. With the first works launched in 2011, this project aims to transform the Paris conurbation into a major world metropolis. In addition to a transformation of the urban landscape, the project will also transform the Ile-de-France transport network. From 2020, new links will be put into service and by 2030 these will be ::

200 km of automated network
4 new metro lines (lines 15, 16, 17 and 18)
2 metro line extensions (lines 11 and 14)
71 stations

polygonale_grand_paris — To carry out the polygonals, GEOFIT will have set up or checked nearly 500 vertices on lines 15, 16, and 17.

Preliminary to the construction phase

Since the start of work in 2011, GEOFIT has been awarded several public procurement contracts on behalf of Société du Grand Paris. In this capacity, GEOFIT has been involved in the various key phases of the project, both in the preparatory phase and during the works.

In the preliminary phase of the project, it is essential to define the routes and their impact on the territory. GEOFIT therefore carried out certain topographical surveys to facilitate the studies of these routes and the land management of the project. To do so, our technicians used different acquisition methods: MMS, Lidar, aerial photogrammetry, or GPS. The combination of these techniques allowed the editing of plans from 1/1000 to 1/200.

During the construction work: the northern extension of line 14

The Grand Paris Express project involves the extension of two existing metro lines. Line 14 is thus extended to the north as far as Saint-Denis-Pleyel.

GEOFIT’s teams have been involved in the work on the new Clichy/St Ouen station to carry out

precision implementation
Convergence measures
auscultation of the works
reconciliations

fondation_grand_paris — Overview of the invert of the RER C station and the foundation bars before their removal

The extension of line 14 also involves the construction of a framework structure under the RER C suburban train. The work teams had to deal with several technical constraints:

Digging in very friable sand requiring the ground to be frozen with nitroge
Digging in 6 galleries
Passing under an RER C station without interrupting traffic
Removal of the foundation piles of the RER station
Installation of metal hangers every meter to support the station

The station in a few figures:

4 years of work
160 m long and 16 m wide
25 m below the ground surface
5,000 m² of floor space
70,000 m3 of evacuated soil

tunnelier_cachan — Tunnel boring machine entrance shaft at Cachan

Monitoring: example of external automatic monitoring of a section of line 15 (south)

GEOFIT is supporting the Vinci Group on the works for the new metro line, on the Villejuif <> Clamart section. This section includes 7.9 km of tunnel and the creation of 5 stations.

The very urban environment of the Greater Paris projects requires very strict surveillance measures to prevent possible disorders caused to existing buildings by the digging of tunnels.

Depending on the structures and their close environment, several monitoring methods can be used:

Monitoring : automatic continuous measurements with transmission of alerts (8000 points monitored)
Punctual auscultations, especially at the bottom of wells or galleries
Direct levelling of constructed works and neighbouring buildings

Thanks to its expertise in monitoring and auscultation, GEOFIT is in charge of the topographical surveillance of certain structures and the external control of monitoring operations. The objective of this mission :

Detect X,Y,Z displacements with millimetre precision
Analyzing the causes
Alert the project’s stakeholders
Adapting the works