Thesis (doctoral)--Universität Erlangen.

Thesis (Master of Engineering in Mechanical Engineering)--Cape Peninsula University of Technology, 2018. / South Africa’s railway system is the most highly developed in Africa. There are different kinds of transport systems in South Africa but rail transport is considered as one of an important element of the country’s transport infrastructure. In South Africa, over 2.4 million passengers make use of rail transport to get them to their destinations. However, evidence shows that train accidents have become a common occurrence across the country. Train-related accidents such as collision, derailments, platform change incidents and commuter accidents, cost South Africa over R400 million per year. The analysis of derailments indicates that the most significant single contributor to derailments is rail breaks. This contrasts considerably with prescribed relevant local and international benchmarks, which show a much lower percentage of derailments due to rail break. The frequency of derailments due to rail breaks in South Africa seems to be higher in the northern than the southern region. Furthermore, the proportion of rail breaks that result in derailment is considerably higher than the set benchmarks and therefore, if there is a rail break, then the probability of this translating into a derailment is astonishingly high. Equally, the high incidence of derailments due to rail breaks is affected by the train length and axle load and further exacerbated by the absence of track circuitry. Since derailments are a direct function of the incidence of rail breaks, focus is required to characterize the factors causing defects on rail lines. This study investigated steel rail material by characterising the piece of the damaged rail with the aim to gain a better understanding of the wear mechanism. Chemical composition analysis of steel rail sample was conducted with the use of a Scanning Electron microscopy. Hardness of steel rail was measured with a Vickers hardness tester. An Optical Microscopy was used to examine the microstructure features of the worn rail samples. This study discovered that the worn out rail, which was produced from high carbon steel with pearlite and ferrite microstructure, undergoes decarburization and a plastic deformation process. The decarburization process happens when the rail track is heated to 700 oC and above when the carbon atoms at the surface interact with the atmospheric gases and are removed from the steel as a gaseous phase. Plastic deformation is created when the iron atoms are heated above the elastic point resulting in the permanent movement of iron atoms.

Thesis (M. A.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Thesis (doctoral)--Universität Erlangen.

published_or_final_version / abstract / Transport Policy and Planning / Master / Master of Arts in Transport Policy and Planning

A thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2017 / The principle focus of this research is to provide a novel approach to accident investigation theory by focusing on the investigation process itself as a complex system. A number of systemic factors inherent in this system impact on the effectiveness (accuracy, quality, validity, reliability and objectivity) of railway investigations. There is a need to explore why railway occurrences remain high in South Africa, despite railway Operators investigating occurrences. If occurrences are investigated, why then do the number of events remain unchanged? Ineffective investigations impact on the accuracy of the findings identified and the suitability of the recommendations. Added to this is the failure of implementing recommendations from investigations contributing to the high number of occurrences and repeated occurrences. Complex influencing factors inherent within the railway system influence the actual investigation process and therefore its effectiveness. This is despite interventions put in place by various organisations, industries, and sectors to improve railway safety. A critical review of the literature, in terms of accident investigation theory, indicates that the current research targets various approaches, methods and models to determine why accidents occur; from a human, technical, or system perspective. The literature focusses on accident causation by addressing the system and its role in contributing to such events. However, very little critical analysis exists on the actual investigation process of accidents as a complex system in its own right, and its contributory role in the ongoing high number of accidents. Rasmussen’s (1997) Risk Management Framework is used in this research to illustrate the South African railway system hierarchy. A qualitative mixed methods approach using triangulation was adopted. Methods included a print media analysis of reported railway accidents, document analyses of governance documents, analyses of railway investigation reports, semi-structured interviews with railway investigators and observations of investigation inquiries. Thematic content analysis was conducted to identify the themes emerging from the data. The results indicate that systemic factors influence the manner in which occurrences are investigated. Examples include no National Rail Policy, limited resources to investigate, shortage of skilled investigators, absence of investigator training, non-compliance to governance documents, an underinvestment in rail, financial constraints, and a blame culture. An Accimap summarises the systemic factors impacting on the effectiveness of the accident investigation process, its outcomes and the recurrence of accidents. Conclusions demonstrate that the accident investigation process is indeed an example of a complex system. Systemic factors collectively behave to influence the effectiveness of the investigation process, but also on the bigger rail socio-technical system which impacts on the safety, reliability and efficiency of the South African railway system. The theoretical contribution of this research is identified in the useful and novel application of Rasmussen’s (1997) Risk Management Framework to illustrate that the accident investigation process is an example of a complex system. Adjustments to Rasmussen’s (1997) Risk Management Framework were made in order to contextualize it to the problem of this research, confirming the importance and application of Rasmussen’s work in the system of accident investigations and not only in accident causation. / MT 2018

This dissertation consists of three essays in the field of environmental economics. The first chapter provides the first causal evidence that hostile activities online lead to physical violence. Given the recently documented relationship between pollution and social media, I exploit exogenous variation in local air quality as the first step to instrument for online aggression. In an event study setting, I find volatile organic compounds (VOCs) increase by 7% when refineries experience unexpected production outages. Together with higher air pollution, I find more aggressive behaviors both online and offline, as well as worse health outcomes near refineries. A one standard deviation increase in surrounding VOCs leads to 0.16 more hate crimes against Black people and 0.23 more hospital visits per thousand people each day. Second, I consider how emotional contagion spreads through social networks. On days with pollution spikes, surrounding areas see 30% more offensive and racist tweets and 12% more crimes; those geographically distant but socially networked regions also see offensive and racist tweets increase by 3% and more crimes by 4.5%. Nationally, overlooking spillovers would underestimate crime effects of pollution by 24%. My findings highlight the consequences of social media hostility and contribute to the public debate on cyberspace regulation. The second chapter, which is coauthored with Andrew Wilson, analyzes the relationship between weather and railway accidents. Rail thermal expansion and contraction are key considerations in rail design and construction; rail operators and rolling stock may likewise exhibit vulnerability to temperature changes. We quantify the sizes of these effects by leveraging a comprehensive dataset of railway malfunctions in the United States spanning 1997-2019. We find that both heat and cold cause elevated rates of railway malfunctions, with relatively larger increases in the number of incidents leading to a casualty as well as the number of injuries and deaths resulting from these incidents. We find that exposure to daily temperatures averaging over 30°C (86°F) leads to a 16% increase in the number of rail malfunctions, a 13% increase in the number of incidents leading to a casualty, and 18% and 36% increases injuries and deaths-effects net of any operational adjustments made to mitigate these effects. Further, while we also find that warmer locations exhibit a weaker relationship between heat and railway malfunctions, we find no evidence that companies are learning, year-over-year, how to reduce accidents. Finally, we note that effects of heat are strongest for derailments (versus other types of malfunctions) and freight trains (versus passenger trains). Our findings highlight the vulnerability of the railway system to the climate. The number of injuries and deaths associated with weather exposure-especially in comparison to operators' reported private costs of equipment failure-suggests a role for enhanced rail safety regulations and adaptation funding to protect critical heat-exposed infrastructure. The third chapter, which is a joint work with Douglas Almond and Muye Ru, explores the impact of federal policy rollback on methane leakage. Improvements in satellite measurement enable independent assessment of regulatory and climate policy. In August 2020, the Trump Administration lifted Obama-era requirements that oil and gas firms detect and repair methane leaks. We merge geo-identified data from the European TROPOMI (satellite instrument) to the specific locations of the US oil and gas infrastructure. Using a difference-in-differences design, we find a prompt increase in US methane emissions following the summer 2020 rollback. The number of high-methane emission events from the oil and gas sector more than doubled after the rollback relative to the coal sector, which did not experience the same regulatory rollback. While the oil and gas industry claims it faces a persistent, profit-making incentive to stem natural gas leaks and emissions, we find a large and nimble response by industry to changes in federal policy. Public policies that reduce methane externalities are critical given that global methane concentrations are rising at an increasing rate.

Every year thousands of tons of chemicals are transported by railroad in Delaware County, Indiana. All the rail lines pass through the geographical center of Muncie. Because of population densities close to rail lines is high, the vulnerability is substantial for any kind of chemical spill.To respond to possible emergency problems, the latest technology is needed which can be used in the most efficient and fastest way, so that lives can be protected. GIS can provide detailed, and time sensitive information before and after the disaster, thereby increasing the ability to make better decisions during the time of emergency.According to Gosnell (2004), the Emergency Management Agency of Delaware County is least prepared for any kind of action plan if a chemical spill situation occurs. This research is intended to create an Emergency Management System for a hypothetical chemical spill involving all the five phases of operation using GIS so that it can be a demonstration for the emergency management agency of Delaware County of how such a situation can be planned from its initial stage to final stage of operation thereby the life, property and environment can be protected. / Department of Geography