Grand Paris Express
A case history from TRE ALTAMIRA

200 km of new metro lines in Paris with satellite InSAR surveillance

Gran Paris map

The Grand Paris Express (GPE), with 200 km of underground metro lines, is the largest tunneling project worldwide to use satellite InSAR for monitoring the surface impact of this extraordinary urban development project in Paris.

  • 68 new stations
  • 200 km of underground metro lines

The Société du Grand Paris has chosen TRE ALTAMIRA to monitor the impact of tunneling operations on existing buildings and surface structures along the track and adjacent areas - 1km-buffer zone centred on the network route - using InSAR.

Construction began in mid-June 2016 and will last until 2030. Most of the work is being carried out in dense urban areas and based on the use of complex underground drilling techniques. Risk management and mitigation play a key role and are enhanced by the regular provision of cost-effective InSAR displacement measurements over a vast area.

Historical InSAR Study

to complement existing geotechnical information and to settle subsidence claims.

Historical InSAR study
Before any construction work, InSAR was applied to map historical ground motion and provided an extensive inventory of soil surface behaviour from April 1992 to March 2015, including the identification of vulnerable structures.

InSAR Monitoring

during construction to assess the magnitude of surface motion and its real distribution.

InSAR Monitoring
By providing a density up to 10.000 points of measurements/km², InSAR is also used to complement and calibrate real-time in-situ surveillance (leveling, inclinometres, etc.).

Post-construction

InSAR monitoring to scale back in-situ measurements.

Post-construction
After work completion, InSAR monitoring will be employed to detect any residual subsidence or soil compaction, which might affect surface structures.

Grand Paris Express
Eastern section of Line 15 of the Grand Paris Express: baseline InSAR analysis back to 1992 before work began in mid-June 2016.

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