Objectives of the service
The service offered is a Ground Penetrating Radar (GPR) survey with automated terrain compensation to reduce the time required to conduct surveys and process data used to locate subsurface assets. The assets targeted are largely Utilities. GPR technology is currently available for surveys conducted over flat ground, however, most site terrain where utilities and infrastructure exist is undulating and can be difficult to access due to features such as trees and buildings – see fig.1 below. Over undulating terrain, variations in the angular position of the GPR antenna occur resulting in inaccurate GPR data. TruewaveGPR is a modular system consisting of a GNSS, an inertial measurement unit (IMU) and a data collection system that can be attached to currently available commercial GPR systems using standard interfaces (e.g. USB) to enhance the positioning and imaging capability. The IMU is comprised of 3-axis accelerometers and gyroscopes whose output, when combined with GNSS data, is used to specify the precise angular position of the GPR unit. The TruewaveGPR software automates the merging of IMU with GNSS and GPR data to produce accurate three-dimensional images of the subsurface that are fully compensated for terrain variations. The system removes the requirement of integrating topographical data from a separate survey in post processing thereby reducing overall survey time by up to 50% while improving accuracy over undulating terrain, thus encouraging the use of GPR surveys over terrain which would previously have been deemed too costly or time consuming. The automatic data processing performed by the TruewaveGPR software allows for further time savings by providing clients with same-day results.
Users and their needs
PBU(UK) Ltd., will work alongside various critical infrastructure clients to help endorse and future proof their assets, to enable them to continue to deliver a service to their customers – all utility domains.
TruewaveGPR Technology will provide vital information for preventative maintenance plans, deliver asset renewal programs and increase the level of SHEQ in the construction industry, as well as delivering substantial costs savings in the world of unforeseen circumstances.
TruewaveGPR Technology will have the ability to provide a ‘One Stop Shop’ process for surveys – topographical, undulating terrain and local surveys: UK Infrastructure Market and available for use in a timely manner and accessible via the web page.
Infrastructure: is the underlying structure of a country and its economy, the fixed installations that it needs in order to function – roads, bridges, dams, utility networks – keeping the lights, the power and the water flowing.
Rail Infrastructure: is the multi-disciplinary engineering system from earthworks, tunnels and track systems on which the railways run. Truewave will provide knowledge to the industry that has never had in the uk.
Service/ system concept
Subsurface imaging to locate existing assets and determine routes for information and planning (i.e., Balfour Beatty VINCI, AMCOGIFFEN or Excalon) requiring utilities to be diverted for the installation of new infrastructure. Route planning is improved by detecting and identifying subsurface features that may impede diversion (e.g., buried debris, archaeological features). Subsurface imaging to locate existing assets in areas where direction drilling, excavation or construction work will be carried out. Site planning is improved by detection and identification of the subsurface features that may impede work (e.g., utilities, buried debris, archaeological features). Scheduled ancient monument sites are locations of historical significance which are often situated in remote areas of undulating terrain. Historic England does not allow invasive subsurface investigation as best conservation practice so Ground Penetrating Radar is the preferred method of site investigation. Buckinghamshire county council estimates that some 7,000 designated heritage assets will be affected by the London to Birmingham phase of HS2 alone, many of which are remote scheduled monument sites. • Locating subsurface assets for infrastructure work (i.e., Balfour Beatty laying new HS2 rail tracks along new route). Planning is improved by detecting and identifying subsurface features that may impede progress (e.g., buried debris, archaeological features). Two service types will be available ‘Off-Road’ and ‘Local’ surveys:
‘Off-Road’ surveys – TruewaveGPR attached to the thirty-four antenna IDS system mounted on a vehicle. This configuration will cover large survey areas where square kilometres of undulating terrain can be surveyed per day.
“Local” surveys – TruewaveGPR attached to the manually moved two antenna Cobra system. This configuration is used to survey small areas where a vehicle deployed system is not required, or in areas where obstacles would severely impede the manoeuvrability of a vehicle. It is likely that most surveys will have areas of flat terrain and undulating terrain, and some will require the use of both service types shown above. The benefit of our surveys is that a much larger areas of the site can be surveyed with automated results delivered promptly compared to existing GPR services.
The customers identified are:
Balfour Beatty VINCI
Space Added Value
The GNSS receiver will utilise GPS and Galileo to determine the position of the radar unit. To fulfil our requirements for sub-decimetre accuracy we would select RTK (real-time kinematic). This level of accuracy is required to determine the trajectory of the radar unit to a level of precision such that it can be used in combination with IMU data to find the angular position of the antenna as a function of time in post processing, without requiring an external reference such as the Earth’s magnetic field (which can exhibit significant spatial variation). Although real-time GNSS data for this demonstration project is not essential and would incur costs over PPP it would allow for a reduction in post-processing time so would be beneficial for TruewaveGPR surveys. We feel this is cost effective for the time savings and for projects proposed in the first two years of commercialisation we anticipate RTK networks will be accessible. However, as we progress into the commercialisation of TruewaveGPR there will likely be environments where network RTK is not feasible or is not as accessible. In this case we would choose to use PPP or PPP-RTK if appropriate. Accuracy levels and feasibility for PPP, RTK and PPP-RTK used with TruewaveGPR will be assessed in the first three months of the demonstration project and defined prior to the Baseline Design Review. The GNSS receiver allows the translational position of the GNSS signal to be determined which will be merged with the data from the IMU and the GPR signal to provide a 3D data set used to create a visual representation of the subsurface. Alternatives to GNSS are map grids which are time consuming and would not allow the automated integration of the data with the IMU and GPR data.
The Demonstration Project started in October 2022 and the Baseline Design review (BDR) took place successfully in February 2023. PBU continue to work with Quantum and MEV moving towards the Critical Design Review (CDR) Meeting in March 2023.