| Summary: | The study described in this thesis is concerned with the touch and step voltage problems due to rail potential 'rise 'and the electro-chemical corrosion problem due to stray 'current in DC powered electric I railways. The two problems are interrelated and are both affected by system design philosophies and by operational conditions. In the past, various approaches to these problems have been based on experience accumulated over many years of railway construction and operation. However, without detailed 'studies, it has not been possible to' make realistic comparisons between the different approaches on a scientific basis. In order to assess the merits and demerits of different approaches, objective parameters are proposed in this thesis: the worst-case rail potential, rail potential envelopes, the total stray current and the gross leakage charge. In order to calculate these objective parameters and obtain other detailed data, mathematical` models are constructed and a comprehensive range of computer simulation software developed. These include both static and, dynamic models. Static models are used to evaluate the objective parameters under assumed conditions. Dynamic models, which are integrated simulators that combine the static models with the multi-train simulator, are used to simulate 'practical railway operations. Finally, the theoretical models are validated by practical tests, both in laboratory and on-site. Favourable agreement is obtained between simulation and test results.
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