Analysis using surface wave methods to detect shallow manmade tunnels

Multi-method seismic surface wave approach was used to locate and estimate the dimensions of shallow horizontally-oriented cylindrical voids or manmade tunnels. The primary analytical methods employed were Attenuation Analysis of Rayleigh Waves (AARW), Surface Wave Common Offset (SWCO), and Spiking Filter (SF). Surface wave data were acquired at six study sites using a towed 24-channel land streamer and elastic-band accelerated weight-drop seismic source. Each site was underlain by one tunnel, nominally 1 meter in diameter and depth. The acquired surface wave data were analyzed automatically. Then interpretations compared to the field measurements to ascertain the degree of accuracy. The purpose of this research is to analyze the field response of Rayleigh waves to the presence of shallow tunnels. The SF technique used the variation of seismic signal response along a geophone array to determine void presence in the subsurface. The AARW technique was expanded for practical application, as suggested by Nasseri (2006), in order to indirectly estimate void location using a Normalized Energy Distance (NED) parameter for vertical tunnel dimension measurements and normalized Cumulative Logarithmic Decrement (CALD) values for horizontal tunnel dimension measurements. Confidence in tunnel detects is presented as a measure of NED signal strength. Conversely, false positives are reduced by AARW through analysis of sub-array data. The development of such estimations is a promising tool for engineers that require quantitative measurements of manmade tunnels in the shallow subsurface --Abstract, page iii

Evaluation of new technologies to support asset management of metro systems

Since 1930, London Underground Limited (LUL) has performed visual inspections to understand the condition of the physical assets such as tunnels, bridges and structures. The major problem with this kind of inspection is the lack in quality of the data, as it depends on the ability of the inspector to assess and interpret the condition of the asset both accurately and with repeatability. In addition, data collection is time-consuming and, therefore, costly when the whole of the metro network needs to be regularly inspected and there are limited periods when access is available. The problems associated with access to the infrastructure have increased significantly with the implementation of the night tube and will increase further as the night tube is extended over the next 5 to 10 years. To determine the condition of metro assets and to predict the need for intervention, monitoring the changes in the assets’ condition is key to any further evaluation and maintenance planning. This thesis presents the outcomes of using new technologies such as Thermography, Kinematic and Static Laser Scanning, Close-Range Photogrammetry and Total Station to measure defects, such as water seepage, mortar loss in joints, lining face loss (in brick tunnels), cracks, corrosion, voids, cavities and spalls. Each technique is explored through three case studies that evaluate the performance and limitation in the determination of the asset condition. The first case study was performed to compare and contrast the use of Euroconsult’s high definition laser survey against a Principal Inspection Report to determine the level of consistency in predicting the asset condition. During this case study, reports from laser surveys and principal inspections of brick tunnels and covered ways were compared. This analysis showed that a direct comparison between the two inspections is not appropriate because the laser inspection does not capture all the defects mentioned in the Engineering Standard S1060. It also showed that to close the gap between the laser survey and visual inspection, laser surveys would have to be performed every year in brick tunnels and then compare any changes in asset condition with that from the previous scan. The second case study was performed using Infrared Thermography (IRT) to identify water seepage in the brick tunnels as well as test the system in a configuration that would allow the survey to be done from an engineering train. A set of calibration tests were performed in the lab and later the technique was trialled on an engineering train. The results showed that it is possible to measure the level of moisture on specific parts of the lining and that the comparison of surveys performed at different times can allow asset managers to react before a seepage is established, potentially reducing the risk of system disruption caused by water ingress in tunnels. The data also revealed that this technique could be used for other purposes, such as examining the condition of other assets such as brackets, cable supports and broken light bulbs. The third case study was performed using a Terrestrial Laser Scanner, Close-Range Photogrammetry and Total Station Survey to identify defects in structures. In order to test these technologies, a wing wall, located on the north-east wing of the HC3 underbridge at Ladbroke Grove Station, was chosen. This case study demonstrated that LUL can easily implement this type of technology to inspect rapidly their buildings and structures, being able to identify defects and monitor their assets for translation, rotation and changes in shape during changes in loading or the decay of the structure (insidious decline) and the construction of nearby assets. In this research, a large volume of data was captured, and further work is needed in order to manage the data using ‘big data’ concepts. Although it may not be possible to fully understand the insidious decline of an asset, the use of these techniques allows us to better understand how a civil asset behaves, potentially reducing the amount of reactive maintenance to a minimum, consequently reducing service costs and falls in revenue due to disruptions in the system. To successfully analyse the data from new technologies a combination of skills is required and different or retrained personal will be needed

Water leakage mapping in concrete railway tunnels using LiDAR generated point clouds

Dissertation (MEng (Transportation Engineering)) University of Pretoria, 2021.Light detection and ranging (LiDAR) is a key non-destructive testing (NDT) method used in modern civil engineering inspections and commonly known for its ability to generate high-density coordinated point clouds of scanned environments. In addition to the coordinates of each point an intensity value, highly dependent on the backscattered energy of the laser beam, is recorded. This value has proven to vary largely for different material properties and surfaces. In this study properties such as surface colour, roughness and state of saturation are reviewed. Different coloured and concrete planar targets were scanned using a mobile LiDAR scanning system to investigate the effect distance, incidence angle and ambient lighting have on targets of differing properties. The study comprised controlled laboratory scans and field surveying of operational concrete railway tunnels. The aim of field tests was to automatically extract water leakage areas, visible on tunnel walls, based on the intensity information of points. Laboratory results showed that darker coloured targets resulted in a lower recorded intensity value and larger standard deviation of range. Black targets recorded the lowest intensities (0 - 4 units) with 50% higher standard deviations of range, on average, compared to all other coloured targets which recorded standard deviations of around 12 mm. The roughness of each coloured target showed to largely influence the recorded intensity, with smooth surfaces recording higher standard deviations of measurements. Concrete targets proved that a difference in roughness and saturation was detectable from intensity data. The biggest change was seen with saturated targets where a 70 to 80 % lower intensity value was recorded, on average, when compared to the same targets in their dry state. The difference in target roughness showed to have no effect on intensity when saturated. The laboratory data provided an important reference for the interpretation and filtering of field point clouds. Ambient lighting had no significant effect on all measurements for both the coloured and concrete targets. Field tests conducted on an operational concrete railway tunnel confirmed and demonstrated the ability to rapidly identify, extract and record areas of water leakage based on the intensity and spatial information of point cloud data. This is particularly useful as water ingress is known to degrade concrete, resulting in the earlier onset of corrosion, spalling and loss of strength. The mobile LiDAR scanning system used here proved capable of reducing survey time, which would allow for shorter interval revisits, while providing more quantitative information of the leakage areas. Long-term continuous monitoring of the internal structure of a tunnel will reduce the life cycle costs by removing the need for personnel to enter the tunnels for visual assessments and enable remedial work to be better planned by analysing a virtual 3D point cloud of the tunnel before stepping foot onto site.Transnet Freight RailChair in Railway EngineeringCivil EngineeringMEng (Transportation Engineering)Unrestricte

GPS usage and infrastructure needs for machine guidance and control in the construction projects associated with QDMR

[Abstract]: This dissertation analyzed the GPS usage and infrastructure needs for machine guidance and control, in the construction projects associated with QDMR, in order to provide recommendations for future infrastructure needs. Research studies have confirmed that, GPS usage on machine guidance and control in the construction industry, within a VRS CORS environment increase the productivity of the projects. Investigation about the GPS usage on machine guidance and control, for construction projects, associated with QDMR was selected, as the limit of this study, in order to make recommendations for future infrastructure needs, with respect to a possible VRS expansion. Three main research approaches were designed in the project, and the results were further investigated. Geographical locations, spread and density, budget allocations and the durations of the projects were analyzed, to find out a clear suite of evidence, to prove the argument. The business case and the associated cost /benefit analysis, confirmed that, it is beneficial to expand VRS coverage to allow QDMR, to use machine guidance and control on construction projects in south east Queensland. Results not only demonstrated that, the VRS expansion is possible in the south east region, but also, suggested that multiple strategies should be adopted, when establishing GPS infrastructure in Queensland, as a whole. VRS expansion is suitable for the locations, with high density of construction projects, while other districts may provide with either, independent GPS networks or should still use, stand alone systems. Recommendations on future GPS infrastructure developments in Queensland based on the above findings and further possible research avenues were also included in this dissertation. Recommendations on future GPS infrastructure developments have been prepared for the first time in Queensland, from a research study, considering a situation applied to a major government organization in Queensland. These recommendations may be used by DNRW, QDMR and other potential GPS users, to develop strategies, for designing future GPS infrastructure in Queensland, at government level

Desenvolvemento de modelos de información de infraestructuras segundo estándares abertos e parametrización automática a partir de datos xeomáticos.

It seeks to develop procedures that allow generating information models of these structures, created from the relevant information of the point clouds obtained with these systems. For this purpose, the BIM standards for civil engineering structures, both currently available and those that will be published for the duration of the thesis, will be exploited and adopted. Information modeling techniques will be used in these standards, with the aim of obtaining a system that allows modeling the structures automatically. The models will also be made compatible with other methodologies designed for BIM, whose purpose is to take full advantage of the information available for management and maintenance tasks. Meeting these objectives, an automatic modeling system will be developed according to the BIM standards for transport infrastructures, suitable for automatic feeding from geomatic data and remote sensing, which is in turn integrable into management and maintenance systems for these types of structures of civil engineering.Esta tesis busca el desarrollo de metodologías para la exportación de la información geomática de infraestructuras de transporte, particularmente estructuras ferroviarias y carreteras, obtenida mediante tecnologías de mapeado móvil. Se busca desarrollar procedimientos que permitan generar modelos de información de estas estructuras, creados a partir de la información relevante de las nubes de puntos obtenidas con estos sistemas. Con este propósito, se explotarán y adoptarán los estándares BIM para estructuras de ingeniería civil, tanto los actualmente disponibles como aquellos que serán publicados durante la duración de la tesis. Se utilizarán técnicas de modelado de información en estos estándares, con objetivo de obtener un sistema que permita realizar un modelado de las estructuras de manera automática. Se llevará a cabo también la compatibilización los modelos con otras metodologías diseñadas para BIM, cuyo propósito es el aprovechamiento total de la información disponible para tareas de gestión y mantenimiento. Cumpliendo estos objetivos se desarrollará un sistema automático de modelado según los estándares BIM para infraestructuras de transporte, apto para su alimentación automática a partir de datos geomáticos y teledetección, el cual es a su vez integrable en sistemas de gestión y mantenimiento para este tipo de estructuras de ingeniería civil.Esta tese busca o desenvolvemento de metodoloxías para a exportación da información xeomática de infraestruturas de transporte, particularmente estruturas ferroviarias e estradas, obtida mediante tecnoloxías de mapeado móbil. A tese busca o desenvolvemento de procedementos que permitan xerar modelos de información destas estruturas, creados a partir da información relevante das nubes de puntos obtidas con estes sistemas. Con este propósito, se explotarán e adoptarán os estándares BIM para estruturas de enxeñería civil, tanto os actualmente dispoñibles como aqueles que serán publicados durante a duración da tese. Utilizaranse técnicas de modelado de información nestes estándares, con obxectivo de obter un sistema que permita realizar un modelado das estruturas de maneira automática. Levarase a cabo tamén a compatibilización dos modelos con outras metodoloxías diseñadas para BIM, cuxo propósito é o aproveitamento total da información dispoñible para tarefas de xestión e mantemento. Cumplindo estes obxectivos se desenvolverá un sistema automático de modelado segundo os estándares BIM para infraestruturas de transporte, apto para a súa alimentación automática a partir de datos xeomáticos e teledetección, o cal é a súa vez integrable en sistemas de xestión e mantemento para este tipo de estruturas de enxeñería civil

Making space: The natural, cultural, cognitive and social niches of human activity

This paper is in two parts. Part 1 examines the phenomenon of making space as a process involving one or other kind of legal decision-making, for example when a state authority authorizes the creation of a new highway along a certain route or the creation of a new park in a certain location. In cases such as this a new abstract spatial entity comes into existence – the route, the area set aside for the park – followed only later by concordant changes in physical reality. In Part 2 we show that features identified in studying this phenomenon of legal spacemaking can be detected in other spheres of human activity, for example in planning (where spacemaking is projected into the future), and in reasoning about history (where spacemaking is projected back through time). We shall see that these features display themselves in especially complex ways in our everyday use of language, and we conclude by examining the implications of this complexity for attempts to create an artificial intelligence that would enjoy a mastery of language that would be equivalent to that of human beings

Application of optical techniques to surveying

This thesis addresses the problem of acquiring spatial data concerning points on the surface of structures such as underground tunnels and sewers. These data can usefully provide knowledge of deformation, shape, area, volume, and position of structures. Such data can be further analysed to give insight into clearances, deterioration, flow rates and in-fill volumes or can be used to give knowledge of the present state of structures and their position. Few systems address the problem of reliably acquiring this data in a manner that is fast and accurate while remaining flexible, adaptable and robust. This thesis considers a solution to the problem of fast and accurate spatial data acquisition concerning commonly found structures using the technique of optical triangulation with a linear array camera and diode laser light source. Optical triangulation is a technique that has not fully matured for medium range measurement with few systems having been developed and little research material produced. However, the research carried out for this thesis shows that providing all the factors that contribute errors of measurement are understood, then a fast, robust and high accuracy system can be developed. The development of the optical triangulation technique for use in surveying was addressed through a programme of prototype development, testing, and refinement. Three prototypes were built that demonstrated the reliability, accuracy, speed and robustness of this technique. The errors associated with the a triangulation measuring system when applied to surveying application is considered from the intrinsic errors which are the same for any triangulation system and the extrinsic errors which are particular to the use of this system in surveying situations. A calibration bench was constructed for consideration of the triangulation system which was automatic and used an interferometer to provide high accuracy measurement of the performance of the triangulation system. Calibration and interpolation trials were conducted and the results analysed. An analysis of the subpixel accuracy achieved with the discrete pixel CCD imagers has been performed and an analysis made. One of the main disadvantages of optical triangulation when applied to the range 0-5 metres is that of non-linearity. A method of correction has been developed and analysed which is believed to be novel and makes a significant improvement to the measuring system. The conclusion of this research is that an improved system of measurement has been produced which has a number of novel features. Trials show that the measuring system could be developed commercially to provide a solution to measurements of structures within the range of the device and with greater accuracy than comparable equipment designed for the same purpose

The Chorography of the Modern City

Until the nineteenth century, space was represented and produced through mathematically constructed drawings: plans and sections captured buildings and the scientific map recorded the territory. The development of technologies of transport brought crisis into this static and balanced world as speed and displacement radically reconfigured the subject’s orientation. This thesis examines the maps, plans, guides and signs produced in Britain in the nineteenth and twentieth century to accompany railway travelling, motoring, underground commuting and walking in the city, arguing that they indeed became chorographies of the modern metropolis. These modern chorographies not only exploited the possibilities of the graphein in order to deal with the complexities of space, time and movement, but they also prescribed a very specific knowledge, one that dictated a new way of being in space. In fact, they created a new set of spaces altogether