Grand Paris Express : railway inspection by chains inclinometer system

Railway inspection by Cementys for a construction site of Le Grand Paris Express project, using the chains inclinometer system.
Context and Objectives

As part of “Le Grand Paris Express line 15, section T2C” project, Cementys undertook an inspection mission of the SNCF railways by chains inclinometer system.

The aim of this inspection system is to guarantee the durability of the site for a short and long period. And check the impact of the work for the whole structure, while staying alert in case of the development of an anomaly and/or a risk for the security.

To avoid any problems link to parked trains, climate hazards, measurements frequencies… we suggest an inspection methodology of the SNCF railways at the same time, while doing the OA808 constructions by chains inclinometer..

It’s an alternative method to the topographic approach, that has been implented in our system since the last two years. This new inspection system is not affected by the weather, when tracking trains. And also needs less maintenance than the other “Classic” system, by theodolites.

Railway inspection chains inclinometer Cementys

Chains inclinometer system

Task description

The OA808P is located at Villiers Sur Marne, near the SNCF railways.

Nature of work : Molded Walls and Tunnel Branch Works

Cementys aucultation ferroviaire inclinomètres chaînés plan

Work Plan

System Presentation

The system is a bi-axes inclinometer TiltLog made to observe the railways.

Type of sensor : 3D-MEMS bi-axial inclinometer with a 3D positioning MEMS correction, supplied by a Japanese company.

Sensors were placed on concrete ties by gluing system and wooden ties by riveting. They are link to a wire system and connected to a data acquisition. A wireless system is also available for comming installations. 


Sensor : bi-axial Tiltlog 


The bi-axial TiltLog sensors allow to measure both crosswise and longitudinal angle. The measurement frequencies are less than 5 minutes. 

The angular displacements measurements of each sensor are used for railway calculation.

  • Failing deviation
  • Left
  • Longitudinal leveling
Cementys aucultation ferroviaire mesures angulaires

Pattern of angular measures

Track Geometry

Data Processing and Visualization

A real-time data processing system has been developed by the Data team of Cementys.

However, a thermal correction must be applied to make up the reversible effect of the temperature.

And the aberrant measures of rain crossings must be eliminated.


Cementys aucultation ferroviaire mesures

Measures to take thermal corrections into account


The Data quality is proved to be consistent.

The chains inclinometer system has the advantage to measure easily high frequency, during railway inspection. It can also prevent by warning us if there is any problem on the railway, and if necessary stop the traffic earlier thanks to this system.