Kinematic GPR-TPS Model for Infrastructure Asset Identification with High 3D Georeference Accuracy Developed in a Real Urban Test Field

Abstract

This paper describes in detail the development of a ground-penetrating radar (GPR) model for the acquisition, processing and visualisation of underground utility infrastructure (UUI) in a controlled environment. The initiative was to simulate a subsurface urban environment through the construction of regional road, local road and pedestrian pavement in real urban field/testing pools (RUTPs). The RUTPs represented a controlled environment in which the most commonly used utilities were installed. The accuracy of the proposed kinematic GPR-TPS (terrestrial positioning system) model was analysed using all the available data about the materials, whilst taking into account the thickness of the pavement as well as the materials, dimensions and 3D position of the UUI as given reference values. To determine the reference 3D position of the UUI, a terrestrial geodetic surveying method based on the established positional and height geodetic network was used. In the first phase of the model, the geodetic network was used as a starting point for determining the 3D position of the GPR antenna with the efficient kinematic GPR surveying setup using a GPR and self-tracking (robotic) TPS. In the second phase, GPR-TPS system latency was quantified by matching radargram pairs with a set of fidelity measures based on a correlation coefficient and mean squared error. This was followed by the most important phase, where, by combining sets of “standard” processing routines of GPR signals with the support of advanced algorithms for signal processing, UUI were interpreted and visualised semi-automatically. As demonstrated by the results, the proposed GPR model with a kinematic GPR-TPS surveying setup for data acquisition is capable of achieving an accuracy of less than ten centimetres.

Application of Kinematic GPR-TPS Model with High 3D Georeference Accuracy for Underground Utility Infrastructure Mapping: A Case Study from Urban Sites in Celje, Slovenia

“…The unseen network of UUI is very complex in any urban environment [4]. Their importance and utility infrastructure cadastre would not be obvious until hazards and problems arise, such as a gas explosion, road collapse due to subsurface wash-out, water leakage and seepage to the road surface, etc [4][5][6][7].…”

“…The consolidated cadastre of utility infrastructure (CCUI) in the Republic of Slovenia was designed in 2004 as a centralised point of the utility infrastructures (UI) owners, who supply the system with data, and data users. Its purpose is to register all the UI, especially for local and state spatial planning, to prepare the database for the registration of legal rights (ownership) on UI, and to establish a system for the prevention of damage [5]. The following types of UI are registered: energy supply infrastructure (electric energy, natural gas, heating, oil transport), water-distribution system, stormwater drainage, sewer system, street lighting and traffic lighting cables and electronic communications networks [8,9].…”

“…The key motivation for the research was to demonstrate the usefulness of the kinematic GPR model for the acquisition, processing and visualisation of UUI in a real urban environment at least with QL-B. As demonstrated by the results in Šarlah et al [5], the developed GPR model with a kinematic GPR and self-tracking (robotic) terrestrial positioning system (TPS) surveying setup (GPR-TPS model) for data acquisition is capable of achieving an accuracy of less than 10 centimetres in real urban testing pools. The GPR-TPS model was created for high-accuracy underground utilities Three-dimensional (3D) mapping in real-time and only minor adaptations would be necessary for the transfer to fields of GPR investigation in real urban environments.…”

“…A 3D scan was undertaken conventionally by traversing a GPR antenna in an X-Y orthogonal grid on the ground [6,8,15,16]. To eliminate the use of rectangular grids for positioning of a GPR antenna, a global navigation satellite system (GNSS) and TPS can be used by mounting a GNSS receiver or a 360 • reflector (prism) on the centre top of the GPR antenna [5,[17][18][19][20][21][22]. Hence, accurate GNSS positioning is not always available in urban GPR surveys and an alternative method is required.…”

“…As is seen from Table 2 some studies were focused on determining the positional and height accuracy of UUI in a test environment [5,18,19,27] and a few in a real urban site [23][24][25][26]. None of them, other than Šarlah et al [5] and Gabryś et al [27], use TPS to determine the position of the GPR antenna in kinematic mode.…”