Railway instrumentation, temporary retaining walls and frames

Instrumentation and monitoring of the construction site during the works

December 17th 2020

Project : Chartres and Gallardon’s grade seperation replacement

Client : Demathieu&Bard

Location: Massy

Type of monitoring: Railway instrumentation, temporary retaining walls and frames.

The project objectives:

Real-time displacement monitoring of all structures during the works for the replacement of the two grade separators.


Guaranteeing a precise monitoring to ensure the safety of the RER C, B and TGV users.

instrumentation and monitoring works construction site Cementys

Our solutions:

Cementys is working in close collaboration with Demathieu&Bard, to carry out the instrumentation and monitoring of the construction site during the works.

We will be installing Robotic Total Stations, In-place inclinometers and TiltLOGs (tiltmeter) spanning on a 24 months period.  


The goal of an automatic monitoring is to possess in real-time the following data:

  • Railways alignments and levelling
  • Catenary posts displacements
  • Displacements of diaphragm walls, masonry supports of railway bridges and sound screens in x,y,z.
  • Temporary retaining walls tilt
  • Neighboring buildings tilt


The mechanisms will be installed on:

  • The railways and catenary posts of the C, B and TGV lines.
  • Lagging and retaining walls
  • Sound screens, gantries and masonry supports.

Because the project includes multiple steps, our engineering team will have to work closely with Demathieu&Bard and make available their know-how and expertise, depending on the works progress.

All the different installations, removals and reinstallations are set. The first installations for the monitoring of the lines B and C railways began in November.

The data is added to our visualization platform THM Insight, and the different alarm thresholds are set.

Cementys auscultation ferroviaire monitoring