No description available.

Prestressed Concrete Cylinder Pipe (PCCP) is a large-diameter and high-pressure conduit for drinking water and wastewater transmission. Due to its large diameter, high pressure, and mode of breakdown, PCCP failures usually have catastrophic consequences. To mitigate failures, it is very important to assess the condition of the pipe and take proactive measures, such as repair, rehabilitation, or replacement. There are many challenges in assessing the condition of PCCP. PCCP has a complex structure with several layers of materials (e.g. mortar coating, prestressing wire, steel cylinder, and concrete core) working together under loading. This means that there are many factors that can cause pipe failure, and that failure mechanisms are complicated. Data collection could be difficult, and existing data are often unavailable or unreliable. Considerable research has been conducted by scholars and engineers in developing models to evaluate the condition of PCCP. There are mainly two types of models: statistical models, and numerical models using finite element method. Statistical models consider only a few factors, such as pipe age and failure rate, to predict the failure of PCCP. However, the failure of PCCP can be caused by many other factors including pipe material, and loading conditions. Models only considering a few factors are not robust enough for reliable results. The current numerical models assume that all broken wires are centrally distributed in the same location and broken wires have no prestress, thus all broken wires are completely removed from the model. These assumptions could be overly conservative when actual broken wires are distributed in different locations along the pipeline and broken wires have remaining prestress due to the bond between the wire and mortar coating. Therefore, a more comprehensive numerical model is needed to have a better understanding of the condition of PCCP. In this research, an extensive literature and practice review was conducted on PCCP failures to understand the critical factors that affect pipe condition. The available technologies commonly used to detect pipe defects were reviewed in order to better understand the accuracy and uncertainties of the collected data. Existing models were reviewed to better understand their limitations and to advance the research on condition analysis of PCCP using numerical models. Based on these comprehensive reviews, this dissertation proposed a numerical model to analyze the condition of PCCP for its long-term performance management. Detailed structural components such as concrete cores, prestressing wires, steel cylinder, and mortar coating were modelled. The interactions between different layers of pipe components were considered. An algorithm was proposed to account for the bond between the prestressing wire and mortar coating, which is a critical factor for the condition of PCCP with broken wires. A FORTRAN program was developed to assign linear stress distribution between the broken point and the full-prestress resuming point. The proposed numerical model was verified utilizing data from lab tests and forensic study. Lab test data helped to understand the functionality of the model and to verify the model parameters used in analyzing pipe components and the simulation of interactions between different layers. The forensic data helped to verify the model under actual field working conditions of the pipe. Validation of the proposed numerical model was conducted using a 66-inch Embedded Cylinder Pipe and two Lined Cylinder Pipes (42-inch and 48-inch, respectively) from a water utility. In the validation, field data were collected for model development. The simulation results were consistent with the field observation, which proved the validity and applicability of the proposed numerical model in practice. A series of sensitivity studies were conducted to investigate the impact of longitudinal and circumferential location on the structural integrity of the pipe. These investigations showed that considering the actual longitudinal and circumferential location of broken wires is very important to get accurate analysis of pipe condition, while assuming that all broken wires fail in one longitudinal location (assumptions by current numerical models for PCCP) will overestimate the actual damage to the pipe caused by broken wires. To consider the bedding condition, a critical factor for PCCP, the four most common bedding types found in practice were analyzed. Results show that poor bedding could lead to cracks in PCCP, which could cause corrosion in prestressing wires. Therefore, it is very important to account for bedding conditions in the PCCP analysis. The model presented in this dissertation is more comprehensive and robust compared with existing numerical models, and could provide a better understanding of the condition of PCCP. This is because the proposed model considers the contribution of remaining prestress in broken wires due to the bond between the wire and mortar coating. This model can consider the actual longitudinal and circumferential location of broken wires rather than centrally distribute them, and it can consider the actual bedding locations, and the interaction between different layers of materials. This model was calibrated using lab test data and forensic data, and was further validated using field data which showed consistence between simulation results and field observations. The proposed model does have limitations due to limited availability of data and assumptions. Material tests were not conducted to verify the material properties used in the model, which could cause accuracy issues in the results. A full-scale simulation of the interaction between prestressing wire and mortar coating was not considered because it could significantly increase the computation time. Lab tests were not conducted to verify the parameters used for the simulation of interaction between concrete core and steel cylinder which could lead to accuracy problems. Finally, it is acknowledged that the model was only validated in one water utility and validations in more geographically distributed utilities might further test the model's validity and robustness. Nonetheless, the comprehensiveness and robustness of this proposed model improved the analysis of the condition of PCCP. The findings and results of this research will provide guidance for better management of PCCP pipelines for water utilities, and provide reference for future research on numerical modeling of PCCP as well. / Ph. D.

Aging and deteriorating drinking water and wastewater pipelines have become a major problem in the United States, warranting significant federal attention and regulation. Many utilities have begun or improved programs to manage the renewal of their water and wastewater pipes and are proactively managing their pipeline assets rather than reactively fixing them. However, the extensive size of drinking water and wastewater systems and the severity of the deterioration problem are such that it is important to prioritize renewal, by assessing the condition of the pipelines and resolving the most severe situations first. There is a variety of condition assessment technologies and methodologies available and in current use. This research incorporates an extensive literature review on actual cases of use of these various condition assessment technologies and techniques. This research also compiles information gathered through interviews and data mining work with utilities across the United States. The combination of case studies collected through literature review and case studies collected directly from utility sources about actual application of drinking water and wastewater pipeline condition assessment practices used have made it possible to synthesize the current practices and trends regarding pipeline condition assessment in the United States. The synthesis also allows for the identification of key lessons learned that should be considered by utilities when implementing condition assessment of pipelines. Recommendations have also been made for research priorities for filling utility needs. / Master of Science

Inom järnvägsunderhåll är tillståndsbedömning en viktig del för att kunna få ett mer effektivt förebyggande underhåll, samt uppfylla krav på säkerhet och tillgänglighet. Förvaltning av järnvägsinfrastrukturen är en del av Trafikverkets kärnverksamhet inom järnväg, ny och innovativ teknik är ett sätt att effektivisera förvaltningen där drönare är ett intressant exempel. Drönare är en ny tekniktillämpning som stöttar en digitaliserad anläggningsövervakning. Genom att använda sig av drönare vid inspektioner kan trafiken på järnvägarna gå som vanligt samtidigt som inspektioner utförs på ett snabbt och smidigt sätt. Syftet med arbetet är att skapa en kartläggning som visar möjligheter för att tillämpa drönare vid inspektion av järnväg och järnvägsinfrastruktur, samt utgöra en grund för drönartillämpningar inom Trafikverkets verksamhet inom tillståndsbedömning av järnvägsterräng. Målet är att göra en plan för hur Trafikverkets verksamhet kan använda drönare för att stötta tillståndsbedömning av järnvägsterräng. Delar av FMECA har använts för att se vilka möjligheter det finns vid tillämpning av drönare på järnväg samt att en SWOT-analys har utförts där det redogörs för vilka styrkor, svagheter, möjligheter och risker/hot det finns när drönare tillämpas vid inspektioner avjärnvägsterräng. Drönare har en stor begränsning då de enligt regler måste flygas inom synhåll för piloten. Om Trafikverket skulle få tillstånd att flyga drönaren utom synhåll skulle möjligheten att inspektera längre sträckor finnas. Om drönare implementeras i Trafikverkets verksamhet kan det innebära en stöttning till de nuvarande metoderna för tillståndsbedömning av järnvägsterräng. Genom analys av intervjuer, litteraturstudier och en fältstudie har resultatet blivit att drönare kan tillämpas för att utföra tillståndsbedömningar av järnvägsterräng och att möjligheter finns för inspektion av järnväg och järnvägsinfrastruktur. Implementering av drönare skulle möjliggöra en effektivisering av tillståndsbedömning av järnvägsterräng. Det kan även effektivisera förvaltningen samt stötta traditionella övervakningsmetoder och stötta uppfyllandet av leveranskvaliteter och författningsefterlevnad. / In railway maintenance, condition assessment is an important part of getting more effective preventive maintenance, as well as meeting safety and accessibility requirements. The management of railway infrastructure is a part of the Swedish Transport Administration’s core in railway operations. New and innovative technology is a way to improve management efficiency, a way to do this is with the help of drones. Drones is a new technology application that supports digitized facility monitoring. By using drones during inspections, railway traffic run as usual while inspections are carried out quickly and smoothly. In railway maintenance, condition assessment is an important part of being able to get a more effective preventive maintenance, as well as meet the requirements for safety and accessibility. The purpose of the work is to create an initial survey which shows what possibilities there are today for applying drones when inspecting railway and railway infrastructure, as well as provide a basis for drone applications inside the Swedish Transport Administration’s operations within condition assessment of railway terrain. The aim is to create a plan for how the Swedish Transport Administration’s operation can use drones to support railway terrain assessment. A part of a FMECA has been used to see what opportunities there are when using drones on railway. A SWOT-analysis have been carried out explaining the strengths, weaknesses, opportunities and risks/threats that exist when drones are applied for inspection of railway terrain. Drones have a big limitation because, according to rules, they must be aired within the sight of the pilot. If the Swedish Transport Administration gets permission to fly drones out of eyesight, the possibilities of inspecting longer distances could occur. If drones are implemented in the Swedish Transport Administration’s operations, it may support the current methods for railway terrain condition assessment. Through analysis of interviews, literature studies and a field study, the results have been that drones can be applied to carry out condition assessment of railway terrain and that there are possibilities to do inspections of railway and railway infrastructure. Implementation of drones would allow for the streamlining of railway terrain condition assessment. It can also streamline administration and support traditional monitoring methods, it will also be able to support the fulfillment of delivery qualities and constitutional compliance.

The topic of the thesis is multi objective condition assessment of water supply systems. The state of the art of condition assessment of water supply systems and the state of the art of multi objective optimization methods are presented within the thesis. Based on these recherches, the uniform methodology of condition assessment of water supply systems and its 7 modules was designed. The thesis deals with the selected modules to condition assessment of water pumping stations, water networks and pipe sections. The output of the methodology is the assignment of a category of the technical condition to the rated object. The proposed methodology was tested on real water facilities and proves the ability of a fair presentation of the technical condition of the object.

No description available.

This research introduces and applies the concept of digital state models for civil infrastructure condition assessment and structural testing. Digital state models are defined herein as any transient or permanent 3D model of an object (e.g. textured meshes and point clouds) combined with any electromagnetic radiation (e.g., visible light, infrared, X-ray) or other two-dimensional image-like representation. In this study, digital state models are built using visible light and used to document the transient state of a wide variety of structures (ranging from concrete elements to cold-formed steel columns and hot-rolled steel shear-walls) and civil infrastructures (bridges). The accuracy of digital state models was validated in comparison to traditional sensors (e.g., digital caliper, crack microscope, wire potentiometer). Overall, features measured from the 3D point clouds data presented a maximum error of ±0.10 in. (±2.5 mm); and surface features (i.e., crack widths) measured from the texture information in textured polygon meshes had a maximum error of ±0.010 in. (±0.25 mm). Results showed that digital state models have a similar performance between all specimen surface types and between laboratory and field experiments. Also, it is shown that digital state models have great potential for structural assessment by significantly improving data collection, automation, change detection, visualization, and augmented reality, with significant opportunities for commercial development. Algorithms to analyze and extract information from digital state models such as cracks, displacement, and buckling deformation are developed and tested. Finally, the extensive data sets collected in this effort are shared for research development in computer vision-based infrastructure condition assessment, eliminating the major obstacle for advancing in this field, the absence of publicly available data sets. / Ph. D.

Highway roughness is a concern for both the motoring public and highway authorities. Roughness may even increase the risk of crashes. Rail-highway grade crossings are particularly problematic. Roughness may be due to deterioration or simply due to the way the crossing was built to accommodate grade change, local utilities, or rail elevation. With over 216,000 crossings in the US, maintenance is a vast undertaking. While methods are available to quantify highway roughness, no method exists to quantitatively assess the condition of rail crossings. Conventional inspection relies on a labor-intensive process of qualitative judgment. A quantifiable, objective and extensible procedure for rating and prioritizing improvement of crossings is thus desired. In this dissertation, a 3D infrastructure condition assessment model is developed for evaluating the condition and performance of rail highway grade crossings. Various scanning techniques and devices are developed or used to obtain the 3D “point cloud” or surface as the first step towards quantifying crossing roughness. Next, a technique for repeatable field measurement of acceleration is presented and tested to provide a condition index. Acceleration-based metrics are developed, and these can be used to rate and compare crossings for improvement programs to mitigate potential vehicle damage and provide passenger comfort. A vehicle dynamic model is next customized to use surface models to estimate vertical accelerations eliminating the need for field data collection. Following, crossing roughness and rideability is estimated directly from 3D point clouds. This allows isolation of acceleration components derived from the surface condition and original design profile. Finally, a practice ready application of the 3D point cloud is developed and presented to address hump crossing safety. In conclusion, the dissertation presents several methods to assess the condition and performance of rail crossings. It provides quantitative metrics that can be used to evaluate designs and construction methods, and efficiently implement cost effective improvement programs. The metrics provide a technique to measure and monitor system assets over time, and can be extended to other infrastructure components such as pavements and bridges.

Increasing cycling as a means of personal travel couldgenerate environmental benefits if associated with acorresponding decrease in car-based transport. In seeking topromote cycling in wintertime, it is desirable to understandhow important the road surface condition is compared to otherfactors in people's decision to cycle or not. In this thesis,the possibility of increasing the number of cyclists byimproving the winter maintenance servicelevel on cycleways isexamined. The attitudes towards cycling during winter ingeneral, and in relation to winter maintenance of cycleways inparticular, is studied through questionnaire surveys. Bicyclemeasurements are related to weather data from Road WeatherInformation System, in order to know the influence on cycleflow during winter from different weather factors. Fieldstudies are performed testing unconventional winter maintenancemethods, in order to see if a higher service level could beachieved on cycleways and if that would lead to an increase inwinter cycling frequency. The field studies are evaluatedthrough road condition observations, measurements of friction,bicycle counts, a questionnaire survey and interviews. A visualmethod to assess winter road conditions on cycleways isdeveloped, in order to compare the service levels achievedusing different winter maintenance methods. There is a clear difference in mode choice between seasons.With improved winter maintenance service level it could bepossible to increase the number of bicycle trips to work duringwinter with, at the most, 18 %, and decrease the number of cartrips with 6 %. However, it could not be concluded with bicyclemeasurements, that an enhanced service level in fact, generateda higher winter cycling frequency. To increase cycling during winter, snow clearance is themost important maintenance measure. Skid control is not assignificant for the choice of mode but is important to attendto for safety reasons. Winter road condition propertiesimportant both with regard to safety and accessibility ofcyclists, are icy tracks formed when wet snow freezes, snowdepths greater than about 3 cm of loose snow or slush,unevenness in a snow covered surface, loose grit on a baresurface. Weather factors with negative influence on winter cyclingfrequency, are temperatures below +5 ° C,precipitationand strong winds. Only the occurrence of precipitation, not theamount of rain or snow, is significant for the cycle flow. Lowtemperatures are more important in reducing the cycle flow thanprecipitation. Temperatures around 0 ° C seem to be extracritical for cyclists, probably due to the larger influence ofprecipitation and slippery road conditions at thesetemperatures. An unconventional method using a power broom for snowclearance and brine or pre-wetted salt for de-icing, provides ahigher service level than winter maintenance methodstraditionally used, but it is about 2 to 3 times moreexpensive. The method has great potential in regions, such assouthern Sweden, with low snow accumulations but with major iceformation problems. To assess the maintenance service level,the visual assessment method developed and tested in thisproject is adequate for the purpose, however, furtherimprovements are desirable. As a complement to the visualassessment, a Portable Friction Tester can be used to measurethe surface friction on cycleways during wintertime. Keywords:Cycleways, winter maintenance, maintenanceservice level, mode choice, winter cycling frequency, wintermaintenance equipment, winter road condition assessment,bicycle measurements, friction measurement.

This doctoral thesis deals primarily with condition assessment of road equipment. The road equipment concept is defined by five main groups, road lighting, fences and barriers, vertical signs, horizontal signs and traffic signals, respectively. Of these groups, road markings, street lighting and barriers of three-lane roads have been studied more in detail. A state-of-the-art, comprising information obtained by comprehensive literature studies on condition assessment of road equipment is presented. Comparably few fundamental studies were found, which, to some degree, can be explained by the lack of suitable physical measurement methods. However, in the case of road marking retroreflectivity, mobile instruments have been developed, and research published in this area is relatively comprehensive. Furthermore, although not based on mobile measurements, several studies on assessments on performance of road sign sheeting have been published. The experimental part of the thesis is divided into four studies, of which two are dealing with mobile measurement of wet road markings and street lighting, respectively. One of the studies concerns condition assessment of road marking performance accomplished in the Nordic countries. Finally, one study comprises risk analysis related to crashes into the barriers on three-lane roads. At road equipment condition assessment, mobile measurement methods are preferable compared to stationary methods. However, many relevant parameters are tricky to measure at speed. One example in this connection is characterization of performance of wet road markings, which has to be based on one or more parameters obtained by measurements on dry surfaces. Results presented in this thesis indicate that retroreflectivity and skid resistance of wet road markings can be predicted based on retroreflectivity and macro-texture of dry road marking. For traffic safety, street lighting is important. The performance of this type of road equipment is in most cases described in terms of luminance of the illuminated road surface. However, luminance measurements are tricky and time-consuming and not useful for condition assessment. On the contrary, measurement of illuminance is easy to carry out and can be performed at speed. One part of the thesis describes how road surface luminance in street lighting can be estimated based on illuminance and reflection properties of the road surface. With the purpose of comparing road marking performance in the Nordic countries, condition assessment using mobile measurement equipment was accomplished in 2002 and 2003. In each of the five Nordic countries, a number of roads were chosen for measuring retroreflectivity. The study showed that the retroreflectivity of edge, centre and lane lines was poor in some countries, but, at least regarding edge lines, this shortcoming could be compensated by use of wide, continuous lines. In other words, the visibility of longitudinal road markings was approximately equal in the different countries. The purpose of the risk analysis performed on three-lane road barriers was to estimate the influence of the time-period between initial crash and repair on the risk of a secondary accident. The result showed that, especially in winter-time, time-reduction means reduced risk of secondary accidents. / QC 20100824