Pont de Lagnieu vu depuis le Rhône

Lagnieu bridge: 1st experiment in the CEREMA "Connected bridges" call for projects

Top News01/13/2022

The information report on the situation of bridges in France, delivered in June 2019 by the Senate's enquiry committee, highlighted serious risks linked to a lack of monitoring and maintenance of bridges. Bridges in France represent nearly 250,000 structures, managed by local authorities or companies such as major transport companies or motorway networks, for example, and require, like all structures, regular maintenance. Operating conditions (number of lorries and weight carried) are primarily responsible for the ageing of engineering structures, followed by environmental conditions.


As part of CEREMA's call for projects, France Relance "Ponts connectés" (in partnership with the Isère Departmental Council and Sercel) is launching the first trial of the technological solution for dynamic analysis of structures, which took place at the end of November on the Lagnieu bridge and will last for three years.

A "Connected Bridges" mission

conducted for CEREMA  

Mechanical arm installing the sensors under the Lagnieu Bridge
Mechanical arm installing the sensors under the Lagnieu Bridge

For the deployment of this new solution, the Conseil Départemental de l'Isère (38) chose the Lagnieu bridge because of its original design (arch-shaped, made up of 6 adjoining arches), its age and its strategic position in road traffic (RD 1075). Crossing the Rhône between the communes of Saint-Sorlin-en-Bugey and Vertrieu, it was rebuilt in the 1950s after being destroyed during the Second World War. The monitoring of the structure will last three years and will allow the exploitation of all the data collected over a long cycle to improve the knowledge and monitoring of the bridges.


The requirements linked to the heritage management of structures and engineering works are numerous and make continuous monitoring and regular maintenance essential throughout the life of the structures. The Structural Health Monitoring (SHM) solution proposed by Apave is based on innovative instrumentation technology using ultra-sensitive sensors for engineering structures. Its objective is to obtain data and process them using Operational Modal Analysis (OMA). This analysis will enable the integrity, health and operational maintenance of the bridge to be assessed over time.


This solution uses sensors installed directly on the bridge structures. Developed by our partner Sercel and extremely sensitive, they allow the precise measurement of the behaviour of a structure thanks to natural ambient vibrations (such as wind, swell, road traffic, etc.) and thus recover precise data on the characteristics of the structures.

Predictive monitoring,

a solution for the future 

Apave experts in front of the monitoring screen, analysing the faults of the Lagnieux Bridge
Apave experts in front of the monitoring screen, analysing the faults of the Lagnieux Bridge

Intelligent sensors of the S-Lynks type, developed by Sercel, are extremely sensitive, completely autonomous in energy, and do not require a wire connection. Remotely controllable and automatically adjustable, they allow the real behaviour of a structure to be measured with extreme precision under natural ambient vibrations caused by external stresses such as wind, swell, microseisms or road traffic, and thus recover the precise dynamic characteristics of the structures.


Thanks to the continuous monitoring of the structure, the data collection will allow Apave experts to interpret the real behaviour of the structure and to monitor its evolution over time in order to detect as soon as possible the appearance of anomalies invisible to the naked eye.


See the mission in pictures


The SHM solution developed by

Apave and Sercel

Apave, a risk management specialist, and Sercel, a world leader in seismic equipment, have combined their skills to offer a unique and innovative SHM solution, using the latest and most sensitive accelerometer technology on the market and operational modal analysis.


"Apave and Sercel are entering into a strategic partnership that combines innovative technology with proven expertise in the field of infrastructure and buildings. This solution will enable real-time monitoring of the integrity of structures and thus extend their lifespan."

Jean-Luc Nectoux - Sector Line Director Infrastructure and Construction at Apave


The continuous monitoring of the structure is carried out via the unique S-lynks solution created by our partner Sercel. Completely autonomous and without any wired connection, the intelligent sensors can be quickly installed on all existing structures, even those with a steep incline. Extremely sensitive, they allow data to be recovered over a wide frequency range, but also at low frequencies (< 1 hz). These data provide precise information on the characteristics of structures such as resonance frequencies, modal deformations or damping.


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