21 January 2025
Automated Topographic Monitoring of the A86 Highway Retaining Wall: A Precision and Trustworthy Project
As part of the redevelopment works on Avenue de la Commune de Paris in Nanterre, a project to instrument the retaining wall of the A86 highway was entrusted to our team. This operation aims to monitor any potential movements and deformations of the wall, which could be caused by the works carried out in the ZAC des Papeteries.
A Partnership Based on Trust
This project follows a successful first collaboration in 2023 with the same client, SPLNA/SEMNA, for the inspection and integrity check of the wall's tendons. Under the supervision of CEREMA, this previous mission demonstrated our expertise and helped reinforce the client’s trust, assisted by the engineering firm Bérim. Building on this success, we were asked to carry out this new project, which has crucial strategic and technical stakes.
Specifics of the Topographic Monitoring Project
The Interdepartmental Directorate of Roads of Île-de-France (DIRIF) requested precise instrumentation of the retaining wall over a 300-meter stretch, between the mosque and the B3/B4 ramp (Nanterre tunnel). Our intervention focused on setting up an automated monitoring system capable of providing real-time data and detecting even the smallest movements.
Key steps of the project include:
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Preparation and installation :
- – Removal of asbestos cement panels from the face of the wall.
- – Installation of more than 60 monitoring prisms and 5 reference prisms, with one point every 2 to 3 panels of the wall.
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Setting up the automated system :
- – Installation of an automated LEICA TS15 1’’ R1000 theodolite on a wall mount, powered by 220V and equipped with a modem and battery.
- – Configuration of an acquisition center to collect continuous data.
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Creating a monitoring platform :
- – Online access for the client, DIRIF, and project managers.
- – Implementation of an SMS and email alert system in case of threshold exceedance.
The system, now installed and operational, measures real-time three-dimensional variations with a measurement frequency of once per hour. The dedicated web platform ensures optimal transparency and responsiveness.
A Sustainable Project for Continuous Monitoring
The estimated duration of this system is 8 months, starting from the end of January 2025. During this period, we will continue to monitor and analyze the collected data, in collaboration with the stakeholders. This project perfectly illustrates our commitment to topographic monitoring: combining technology, human expertise, and rigor to ensure the safety of infrastructures and users.
For any questions or specific requests regarding our topographic monitoring services, feel free to contact us!
