A Diadès innovation

Tunnel inspections require a long presence on site, which is less and less compatible with operating constraints, especially on motorways and other major roads and railways.

The system developed, perfected, and patented by Diadès ID-NT© makes it possible to overcome most of these constraints.

The photo quality acquisition guarantees not only the detection of cracks down to 0.2 mm openings, but also the validation of water and calcite entry areas.

The system optimizes the interest of infrared thermography and other techniques combined in the same cross-referenced acquisition in order to facilitate diagnosis, including the removal of doubt in real time by a confirmed inspector.

View our technical data sheet


Description of the device

The system developed and patented by Diadès is made up of different sensors combined together in a single box. It is placed on a mobile system, with manual or towable push. This mobile system includes the batteries necessary for the device to perform an acquisition over a maximum period of 8 hours without recharging.

Five elements make up the system:


• very high precision cameras in the visual field,

• Infrared cameras,

• distance meters,

• a profilometer,

• temperature / humidity sensors,

• an inertial unit,

• an odometer.


The simultaneous triggering of each acquisition is carried out autonomously, taking into account the distance to the wall, the cone of sight of each camera and the value of the system’s advance towards the walls.





Particular attention was paid to the lighting system. A continuous lighting system was chosen in order to minimize the potential inconvenience of “flash” type lighting for vehicles and operators in the vicinity of the system.

An interface has been developed to allow the control of data in real time during the acquisition. This interface also allows, thanks to the various sensors implemented, the detection on site of areas of disorders or doubts about the state of the structure. A list of reserves, which can be parameterized and identified directly on site, by probing the facing, is thus generated in parallel to the acquisition phase, in order to take advantage of the time slots in place for marking (or the time slots for closing the track) to limit the number of interventions. The system allows to optimize the interest of infrared thermography and other techniques combined in the same cross-referenced acquisition in order to facilitate in fine the diagnosis.


The system is developed with maximum modularity in mind.

For the current structure, the system allows, in addition to the acquisition in tunnels, the realization of inspection in tubes of minimum section of 3.5 m of diameter. It also allows services to be carried out in vertical tubes or shafts.

The system can be adapted for the realization of surface acquisition (roadway, large intrados…) or any other type of structure.

The lights integrated in the system are removable in order to adapt to the different types of lighting present in the inspected structures.




The system allows to optimize the interest of infrared thermography and other techniques combined in the same cross-referenced acquisition in order to facilitate the diagnosis. The development of a specific software allows the integration of all the data acquired in the field. 
These data are positioned in a three-dimensional reference frame, thus offering the possibility of visualizing the structure with integration of visual data (photography in the visual and infrared range) on a 3D viewer. This software, necessary for the data processing, also allows the realization of developed for export and control of the structural state of the inspected work.




The management and creation of the elements are done based on:

• a fluid panorama of the photographs, in the visual domain, straightened and repositioned,

• a fluid panorama of the photographs, in the infrared range, rectified and repositioned, with automatic extraction of the significant zones for superposition,

• the superposition of the two panoramas,

• direct entry of pathologies by the senior inspector,

• a secure export of the generated data,

• profiles,

• temperature and humidity.



How it works


The technology consists of scanning the underside of a structure in a single pass at a speed of between 1 and 3 km/h, thus limiting the number of night-time interruptions. The real-time reading combined with an alert system makes it possible to identify (with the help of thermography in particular) the zones that may represent a doubt about certain disorders.


The presence of an experienced inspector during the acquisition allows to arbitrate these alerts in real time but also to remove the doubts by accessing (by means of a cherry picker) directly to the contact of the facing and the concerned parts of the structure. The presence of the inspector also makes it possible to inspect the zones not accessible by the automated means (caps, inter-pipes, drainage network, zone of influence) which are an integral part of the findings in the detailed inspection report.


At the end of the intervention on site, the inspectors have therefore a set of photographic acquisition in the visual and infrared domains of the lower part of the structure and have cleared all the areas of doubt that they would have had to deal with after the event if they had only used the scanner acquisition method.


The quality of the photographic and thermographic supports will allow the inspector, once off site, to finalize the observations of the lower surface and to carry out the mapping of the disorders on a developed support.




The reports are those expected in fascicule 40 of the technical instruction with in particular the identification sheet of the structure, the findings, the IQOA rating, the follow-up, a photographic report, a map of the disorders as well as a photographic detailed report of the intrados of the structure.


The development of this method has led to a concrete application in the context of several detailed inspection campaigns under severe motorway operating constraints, notably for the Escota – Vinci Autoroutes network and the Aprr-Area network.



Thanks to its experience with the numerous services provided with the current version of the system, Diadès is continuously improving both the physical components (sensors, internal system management parameters) and the software developments.


An ID-NT V2© version will be operational during 2021. It will allow the improvement of the inputs and outputs in order to obtain better quality results and also to implement additional parameters.


These developments are mainly focused on the 360° acquisition coverage area (in the visual and infrared domains), the speed of acquisition in “stealth” mode, the optimization of acquisition quality, the optimization of acquisition management and the processing of output data.