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Novel Subsurface Inspection Radar to Inspect Tunnels and Tunnels Linings for improved maintenance.

Periodic Reporting for period 1 - TUNNEL VISION (Novel Subsurface Inspection Radar to Inspect Tunnels and Tunnels Linings for improved maintenance.)

Reporting period: 2019-01-01 to 2019-06-30

Currently non-destructive inspection of tunnels relies on acoustics involving an inspection engineer hitting the tunnel wall with a hammer and recording the reflected sound. This is obviously simple to use and any loose concrete can be removed using the hammer. Disadvantages include the long inspection time in total, the need for many engineers and the elevated working conditions, but the major difficulty is the interpretation of the acoustic data. These failures can develop into serious hazards that threaten transport safety and efficiency due to catastrophic unpredicted tunnel damage. The clear challenge is to use innovation for advanced subsurface infrastructure inspection to avoid expensive, inaccurate and time consuming acoustic testing. The TUNNEL VISION project will build and demonstrate radar equipment capable of forming 3D images of the subsurface using rotating antennae. TUNNEL VISION produce high-resolution images that can be easily interpreted by end-users improving safety and efficiency of tunnels while reducing delays, maintenance costs and the potential for catastrophic damage. The creation of clear 3D augmented reality images will allow civil engineers to accurately determine the tunnel infrastructure failures which will improve: whole life performance, resilience, reduce risk and effects of failure as well as reducing costs, plan maintenance and enable a predictable timescale for works and examine and repair fault(s). All tunnel infrastructure owners, operators and maintainers will benefit from the commercialised Subsurface Tunnel Infrastructure Inspection Radar system. The overall result is that TUNNEL VISION will be able to examine and evaluate the entire tunnel, subsurface regions as well as the tunnel utilities. This will maintain and improve levels of safety on rail and road networks, whilst reducing maintenance time and costs. Early detection and evaluation of anomalies that current technology cannot, allows potential hazards to be eliminated through specifically targeted maintenance, thereby increasing safety and decreasing costs, these are unique selling points for the European and global markets.
The TUNNEL VISION feasibility study began with desk research on the current state-of-the-art of tunnel maintenance and construction in the Europe. This was to create a deeper understanding of why failures occur and to what extent they impact tunnel structure which can in turn lead to disruption of services and commercial penalty and an increased risk to the health and safety or passengers and maintenance teams. With the results of this research in mind a questionnaire was designed, with 10 questions and put onto the Survey Monkey software package to allow respondents to complete them on-line and also use them as the basis when interviewing face-to-face. Respondents were taken from experts in geotechnics, tunnel engineering and tunnel construction management, with special expertise in transportation and infrastructure projects. The questions covered the organisations current inspection methods and the type of tunnels maintained, e.g. brick lined and the age of the tunnel; the level of crew required for maintenance; the type of defects identified and the costs of repair; potential risks to the health and safety of passengers, freight users and the maintenance crew. The results of these questionnaires and face-to-face interviews was that there is a clear need for a better system of identifying the exact type of fault in tunnels and reducing the costs associated with it whilst at the same time increasing the health and safety of passengers; freight users and crew working on maintenance. It is clear that TUNNEL VISION has commercial exploitation opportunities and can be exploited with end-users such as infrastructure owners/managers/operators. TUNNEL VISION has been disseminated to tunnel infrastructure owners, operators and maintainers who will benefit from the commercialised Subsurface Tunnel Infrastructure Inspection Radar system and will examine and evaluate the entire tunnel subsurface regions as well as utilities. The feasibility study is also disseminated through the Euromobilita website and directly with tunnel infrastructure end-users. TUNNEL VISION will remain on the internet and developments in TUNNEL VISION will be updated as progress in made.
There are two main foci of innovation in the TUNNEL VISION project. The first is the novel rotational kinematics of the antennae, which allows data to be collected continuously from a three-hundred sixty-degree swath about the longitudinal axis of the vehicle. This offers a significant competitive advantage over current state-of-the-art systems, which consist of several vertically fixed antennae uniformly positioned along the vehicle’s lateral axis, and are therefore limited to acquiring discrete data transects within the lateral extent of the vehicle. In contrast, TUNNEL VISION can provide comprehensive, three-dimensional images of subsurface regions at extended lateral distances from the road or rail centreline, enabling it to map unknown subsurface structures, and to detect and localise hazards such as voids, collapses and pooled water. It has the capability to evaluate the condition of tunnel infrastructure, ranging from near surface cracks to larger air and water filled voids that could threaten structural integrity. The second focus is on fundamental processing software to transform the raw radar data into subsurface images, which will be developed in parallel with the prototype. The algorithm will utilise tunnel surface topography and impedance (which can be determined by laser reflectometry and the amplitude of radar backscatter from the ground-air interface, respectively) to compensate for radar beam refraction at the ground-air interface. The feasibility study was used to prepare for commercialisation and demonstration of this novel, portable radar system that provides a simple non-invasive mechanism for inspecting tunnel infrastructure. At present current Ground Penetrating Radar techniques are not reliable and therefore invasive techniques are required to inspect tunnel structures. The TUNNEL VISION system is innovative, unique and rail infrastructure managers believe it has a large market potential. The overall effect of this for wider society is that there will be increased confidence in the ability to detect faults and anomalies in tunnels and thereby increase the safety of maintenance crews; users of freight vehicles and passengers.
Rail vehicle mounted TUNNEL VISION to determine subsurface tunnel defects down to the excavation
Vehicle mounted TUNNEL VISION system