Road smoothness is one of the most important road functional characteristics because it affects ride quality, operation cost, and vehicle dynamic load. There are many types of devices that measure the road profile, which is often used to compute different smoothness indices. The development of performance-based specifications and pavement warranties that use ride quality as a performance measure has increased the need for accurate measurement of pavement smoothness. For this reason, researchers have compared and evaluated the performance of available profilers and several profiler accuracy criteria have been proposed. However, there is not a definite answer on the ability of available profilers to accurately measure the actual road profile as well as the various smoothness indices. A recent profiler round-up compared the performance of 68 profilers on five test sections at Virginia Smart Road. The equipment evaluated included high-speed, light-weight, and walking-speed profilers, in addition to the reference device (rod and level). The test sites included two sites with traditional hot-mix asphalt (HMA) surfaces, one with a coarse-textured HMA surface, one on a continuously reinforced concrete pavement (CRCP), and one on a jointed plain concrete pavement (JCP). This investigation used a sample of the data collected during the experiment to compare the profiles and International Roughness Index (IRI) measured by each type of equipment with each other and with the reference. These comparisons allowed determination of the accuracy and repeatability capabilities of the existing equipment, evaluation of the appropriateness of various profiler accuracy criteria, and recommendations of usage criteria for different applications. The main conclusion of this investigation is that there are profilers available that can produce the level of accuracy (repeatability and bias) required for construction quality control and assurance. However, the analysis also showed that the accuracy varies significantly even with the same type of device. None of the inertial profilers evaluated met the current IRI bias standard requirements on all five test sites. On average, the profilers evaluated produced more accurate results on the conventional smooth pavement than on the coarse textured pavements. The cross-correlation method appears to have some advantages over the conventional point-to-point statistics method for comparing the measured profiles. On the sites investigated, good cross-correlation among the measured and reference profiles assured acceptable IRI accuracy. Finally, analysis based on Power Spectral Density and gain method showed that the profiler gain errors are nonuniformly distributed and that errors at different wavelengths have variable effects on the IRI bias. / Master of Science

No description available.

Clinch Dace (Chrosomus sp. cf. saylori) is a newly recognized species of minnow with a restricted distribution in southwestern Virginia. Field sampling and genetic analysis support the hypothesis that Clinch Dace populations are small and fragmented. Analysis of neutral genetic markers shows that most Clinch Dace populations have undergone past bottleneck events and are being operated upon by random genetic drift. Bayesian cluster analysis showed that three out of the seven populations found in 2017 are distinct, while the other four show signs of more recent admixture. However, Fst values among streams were high and analysis of molecular variance indicated differentiation among populations in all streams. These findings support the view that these populations are genetically isolated. Effective populations sizes were low at most sites, enhancing the likelihood of loss of alleles to genetic drift. Low M-ratios, non-zero Fis values, and high degrees of relatedness among individuals indicate that some inbreeding is taking place. Habitat analysis did not identify variables affecting distribution or abundance of Clinch Dace populations. As the collection sites were targeted near known Clinch Dace occupied sites, it is likely that habitat variables known to impact Clinch Dace, such as conductivity, were within the species' range of tolerance. Results showed that Clinch Dace seem particularly resilient to sedimentation, corroborating earlier work showing a negative relationship between Clinch Dace abundance to sediment size. That is, small sediment size does not seem to have a negative impact on Clinch Dace abundance. Of all sites where Clinch Dace were found, only one culvert at one site was clearly perched and may present a barrier to upstream migration, a possibility which is supported by the genetic differentiation found among collections above and below that culvert. While this study demonstrates that selectively neutral genetic differentiation has taken place among Clinch Dace populations, it does address any local adaptation that may be taking place which would render translocations a risk for outbreeding depression. The findings of this study can inform conservation management in identifying possible sources of individuals for translocations among populations or for augmentation following captive breeding. / Master of Science / The Clinch Dace is a small, threatened minnow in the Clinch River basin that was unknown until 1999. Since then, research has addressed the biology, life history, and distribution of this fish. This study used data from selectively neutral genetic markers to analyze the population structure and degree of differentiation of Clinch Dace populations. My study sites were targeted at road crossings near known Clinch Dace populations to assess the effect of habitat fragmentation on Clinch Dace populations and to maximize the likelihood that I would collect enough genetic material for analysis. Genetic analyses showed that while there is some admixture among certain populations of Clinch Dace, there is differentiation at neutral genetic markers. This differentiation does not necessarily indicate adaptive variation among populations which could result in outbreeding depression should populations be mixed through translocations, but it is reason to proceed with caution. Road crossings were generally not found to be a cause of further population fragmentation in Clinch Dace, as demonstrated by genetic analysis and statistical analysis. Almost all of the occupied road crossing sites in this study were either embedded, free-flowing culverts that were not perched or small bridges, and these were not deemed to be obvious barriers to fish movement. The only exception was Hart Creek 2, where the culvert is slightly perched and Fst is high between populations in the upstream and downstream reaches. The results of this study will help to inform managers as to what conservation actions can be taken to improve population viability. One potential management action from this study could be the retrofitting of culverts that have become perched and are acting as barriers to Clinch Dace movement. Another potential conservation strategy is to translocate individuals from large population to small populations. The study determined: 1) which translocations might be acceptable based on the degree of genetic differentiation among populations, and 2) identified potential donor and receiving streams for translocations.

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In many arid regions, particle ingestion can occur within propulsive gas turbines. The ingested particles can severely impact performance and may damage many primary gas path components through erosion or deposition. Characterizing crystalline deposits on metallic substrates can allow for the prediction of deposition to improve component resilience and develop health monitoring algorithms. This work investigates the effect of temperature and angle on sand deposits and attempts to quantitatively characterize the deposition of Arizona Test Dust (ATD) onto Hastelloy X. The first study presented in this thesis describes a preliminary investigation of sand deposition at temperatures and velocities similar to those found in the turbine section of propulsive gas turbine engines and presents an equation for predicting deposition as a function of gas path temperature and impact angle. The sand and air mixture maintained a constant flow velocity of approximately 70 m/s, impact angle was varied from 30° to 90°, and the gas path temperature was varied from 1000 °C to 1100 °C. The number of deposits was found to linearly increase with temperature for all coupon angles tested. The model was able to explain approximately 67% of the deposition that occurs, with the remaining percentage due to other factors such as injection rates and surface temperature. The second study describes an improved investigation of sand deposition and presents an equation for predicting deposition as a function of surface temperature and impact angle. This study characterizes deposition using percent coverage in addition to deposits per square millimeter. Deposition is a quadratic function of both near surface coupon temperature and coupon angle. The model using deposits per mm2 was able to explain 96.3% of the deposition that occurred and the model using percent coverage was able to explain 98.9% of the deposition that occurred. / Master of Science / In desert regions, sand particles can be sucked into helicopter and airplane jet engines which can severely impact performance and may damage many engine components through erosion or hot deposits. By measuring the sticking properties of sand on materials used in jet engines, equations to predict sticking can be created and combined with previous erosion research to develop computational simulations of sand behavior in jet engines. This work investigates the effect of temperature and angle on sand deposits and numerically characterizes the deposition of sand particles onto jet engine materials. The first study presented in this thesis describes an initial investigation of sand deposition at temperatures and speeds similar to those found in the turbine section of jet engines and presents an equation for predicting deposition as a function of flow temperature and impact angle. The model was able to explain approximately 67% of the deposition that occurs, with the remaining percentage due to other factors such as injection rates and test coupon surface temperature. The second study describes an improved investigation of sand deposition and presents an equation for predicting deposition as a function of metal surface temperature and impact angle. The model is able to explain 98.9% of the deposition that occurred. The improved sand sticking model will allow designers to improve engine resilience and develop health monitoring algorithms. Improved resilience and health monitoring will increase airplane safety as well as reducing maintenance and operating costs when flying in sandy or arid regions.

The purpose of this thesis is to find out if it is possible to introduce a higher gross weight of trucks, from the current 64 tonnes to 74 tonnes. It would mean that the Swedish transportation would be more efficient and it would strengthen the Swedish business sector 's international competitiveness and also support the continued productivity, thus an efficient forest infrastructure is the key to obtain this. The report's input are from literatures, the Swedish Forest Agency’s recommended width increases of the road and simulations based on radius and angle of the curves. The results are based on calculations made ​​from the input data. The results of the report shows that the Forest Agency’s recommended width increases are enough to drive a 74 tonnes truck, which means that the 74 tonnes trucks are useable in the forestry after adjustments of the road. An increase from 64 tonnes to 74 tonnes would from an environmental point of view reduce carbon dioxide emissions by up to 11% and also the road would be better preserved when the axle load is distributed in a more efficient way.

Thesis (MBA)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The study involved a detail empirical investigation into the different road studs in use on South Africa’s national road network and how they performed on the network under different road conditions in order to establish which road stud, under what conditions, offers best value for money in terms of life-cycle cost for the South African National Roads Agency Limited. These main questions were asked: What is the most cost-effective/value-for-money stud option for SANRAL to choose for each of the specified road categories? Under which conditions do the studs perform differently and what is the most likely mode of failure of specific studs linked to a specific road condition and road category? The South African and Australian road stud standards were reviewed to gain understanding of which criteria one has to consider when evaluating road studs and what information would be needed for the research. Similar studies on road studs were reviewed to compare the criteria that were looked at, namely Guidelines for the use of Raised Pavement Markers, developed by the Department of Transport in the United States, and Feasibility of using accelerated pavement testing to evaluate the long term performance of raised pavement markers, a research paper by the Florida Department of Transport. This research made use of a standardised questionnaire containing questions on various elements found to be key to the road stud performance. The study was done on approximately 4 659 km of roads in SANRAL’s Western region, consisting of the Western Cape and Northern Cape. From the literature review, it was identified that there is a need for the SABS standards to be updated to include the testing of structural properties of studs. SANRAL should look at the lack in specification requirements when asking for the installation of road studs. From the data available it was observed that the preferred studs were the Ferro Lynx followed by the STA+52 stud. They are predominantly used on the roads that were included in the survey. They perform well on the national roads. The data suggests that these two studs and the Rhino stud are the best-performing studs with the least dislodgement and loss in reflectivity. The STA+52 and Rhino stud, however, are fairly new on the market and more data for theirs full life cycle should be obtained for further monitoring The regression analysis indicated that 36 per cent of the variation in the reflectivity of the Ferro Lynx stud can be explained by the surface width of the road, the traffic volume measured as ELVS and the period installed. All the coefficients were significant with a 5 per cent significance. The prediction tables on the weighted data set, indicated that one should always consider width of road when choosing a road stud and that the reflectivity of studs deteriorates most on the narrower roads.

The computer program WHEEL is a mathematical model which predicts off-road vehicle performance characteristics. The program was developed using empirical relationships resulting from mobility tests on conventional-sized trucks and tires. The model was subsequently validated by comparing the model's predicted values of vehicle performance parameters, such as net drawbar pull, slip, sinkage and torque, with field test results for conventional-sized vehicles. However, validity of the model for predicting the off-road mobility of vehicles with large diameter tires was not established. The purpose of this study was to provide this validation. Values of net drawbar pull and slip for a Case 2390 tractor with 70.2" diameter driven wheels predicted by computer program WHEEL compare favorably with traction data obtained from tractor performance tests conducted by the University of Arizona Department of Agricultural Engineering. Therefore, the model may be used confidently to analyze performance of vehicles with large diameter wheels.

This MSc (Eng) Investigational Project Report entails the evaluation of the Sekhukhuneland Development Programme (SDP). The SDP is a joint initiative of the Donaldson Trust and the Research Centre for Employment Creation in Construction (WORK). Its objective is: to increase the use of labour-intensive methods in the rehabilitation and maintenance of rural roads and other infrastructure in order to contribute to employment generation, skills development, provision of infrastructure and poverty alleviation. In order to achieve this objective an “Association not for gain” called LITE (Labour Intensive Training and Engineering) was formed; the Donaldson Trust provided the finance, and the expertise was provided by The Research Centre (WORK) but with additional support by Employment Intensive Engineering Consultants (EIEC). As the contracting organisation evolved from nothing into the training and engineering company LITE, the number of employees rose from none to fourteen. The University of the Witwatersrand provided a number of students to the project site at Mohlaletse in Sekhukhuneland where they provided voluntary assistance as part of their studies. Many of these students were from the University of Twente in the Netherlands, and it was largely due to their commitment that the project enjoyed such healthy growth. Considering the meagre resources this growth was a remarkable achievement, and it was made possible, not only through the efforts of the students, but also through the acceptance and support of the community. This support included providing accommodation for both students and site management. With a minimum of resources local community members were trained and employed by the SDP over a prolonged period of three years. The SDP evolved into a new programme, the Mohlaletse Youth Service Programme (MYSP), funded by the Umsobomvu Youth Fund. Of the R1.700.000 donated to the SDP, R1.690.000 was used during the evaluated period. Of this sum approximately 50% was spent directly within the Mohlaletse and Monametse community. The SDP consisted out of three main phases. The organisation evolved during the first two phases from no organisation into LITE Section 21, an organisation that could deal with training and engineering based on a strong labour-intensive focus. During the Pilot Phase the programme focused on establishing contact with the community and proving that labouriii intensive construction method could work. The next phase was the Training Phase where the necessary team leaders were trained to perform a variety of construction techniques. These techniques range from drainage structure to roads and buildings. The last phase is the Construction Phase during which the construction went ahead as planned using fully trained team leaders from the local community. The total setting of the SDP was as follows: SDP Phases SDP Periods Organisation SDP Projects - Pilot Phase: Period 1999H None Period Projects Period 2000A Point-of-Fact (Pty) Ltd Period Projects - Training Phase: Period 2001A Period Projects Mohlaletse Money-Cant-Buy Section 21 Period Projects Monametse Period 2001H Period Projects Mohlaletse LITE - Section 21 Period Projects Monametse Period Project Compound - Construction Phase: Period 2002H Period Projects Mohlaletse Period Projects Monametse Period Project LITE-House and LITE-School The main reason for the success has been the substantial involvement of the local Mohlaletse community and the acceptance of the Site Management within the Community. Within the constraints of the programme definition and objectives, the SDP has been a success to its sponsors and beneficiaries. Major problems were encountered within the fields of Labour-Intensive Construction Methods and the Project Management Areas of Knowledge. These should be taken into consideration when a new Constructing-Training Programme is started in future.

Os simuladores de direção são ferramentas de pesquisa que permitem estudar o comportamento do condutor em diversos cenários de direção, de forma rápida, segura e econômica. Este estudo faz parte de um projeto de pesquisa que visa utilizar essas ferramentas na avaliação de projetos de sinalização, antes da sua implantação na rodovia. Em particular, o objetivo deste trabalho foi analisar como os condutores percebem a sinalização vertical dentro de um ambiente simulado de direção, apoiado no uso de um sistema de rastreio do olhar. O andamento da pesquisa abrangeu a montagem do simulador e do sistema de rastreio do olhar, a geração do ambiente simulado de direção, o experimento no simulador para medir a percepção da sinalização dentro do ambiente virtual, e por último, a análise e validação dos resultados. No experimento, 21 condutores dirigiram em um trecho de 10 quilômetros da rodovia BR-116 que possui 31 sinais de trânsito, para mensurar a distância de percepção, o número de fixações e o tempo de observação da sinalização, assim como a variação da velocidade após percepção da mesma. A percepção da sinalização dentro do ambiente virtual foi semelhante à reportada na literatura para estudos em estradas: em média, os condutores perceberam um de cada três sinais, o tempo de observação foi de 360 milissegundos, a distância de percepção foi de 100 metros e somente a percepção dos limites de velocidade foi relevante no comportamento dos condutores. Adicionalmente, obteve-se uma validade relativa entre as velocidades no simulador e as velocidades de operação medidas no trecho estudado. Nesse sentido, os resultados deste estudo sustentam a viabilidade e a validade do simulador de direção na avaliação de projetos de sinalização. Finalmente, como contribuição adicional, propuseram-se medidas para aprimorar a sinalização no trecho estudado e o realismo do simulador de direção. / Driving simulators are research tools that allow studying driver behavior on several driving scenarios, in a safely and cost-effective way. This study pertains to a research project whose goal is to use these tools in the assessment of road signage projects, before their implementation on roadway. In particular, the goal of this study was to analyze how drivers perceive road signs within a simulated driving environment, supported by an eye tracking system. The research development included the assembling of the driving simulator and the eye tracking system, the generation of the simulated environment, an experiment to measure the signaling perception within that environment, and finally, the analysis and validation of the results. In the experiment, twenty-one drivers drove over a ten-kilometer virtual segment of the BR-116 roadway, that has thirty-one traffic signs, in order to measure the number of eye fixations, the perception distance and the observation time over each sign, as well as, the speed change after its perception. The perception of the road signs within the virtual environment was similar to that reported in the literature for on-road studies: in average, the drivers perceived one-third of the traffic signs, the mean observation time was 360 milliseconds, the mean perception distance was 100 meters and only the speed limit signs perception was relevant on the drivers behavior. Furthermore, it was observed a relative validity between the driving simulator speeds and the actual operating speeds in the studied segment. In that sense, this study shows the feasibility and validity of using driving simulators to assess road signage projects. Finally, some countermeasures were proposed in order to enhance both the road signaling of the studied segment and the road signs perception within the simulated driving environment.