A whole life carbon model for railway track system interventions

The aim of this thesis is to develop an integrated methodology for investigating the potential for a range of novel interventions to reduce the whole-life carbon footprint and Life Cycle Costs (LCC) of ballasted track. Existing methods for assessing the socio-economic performance of railway infrastructure have often been found wanting. A review of the academic literature in the field has been undertaken and methodologies with the potential to improve the socio-economic modelling of railway infrastructure have been identified. A modelling framework for environmental and financial appraisal has been developed by combining principles of Life Cycle Assessment (LCA) and Life Cycle Cost Assessment (LCCA) approaches. Its applicability has been tested through a range of exemplar case studies. The framework has been first tested at the component level, by examining the whole life carbon footprint and LCC of the four most common railway sleeper types present in the UK railway network. Then it has been expanded, by incorporating a detailed Life Cycle Inventory (LCI) inventory of different Switch and Crossing (S&C) design variants. This enabled the quantification (at the asset level) of the whole life carbon footprint and carbon costs of fifteen (six turnouts and nine crossovers) designs variants. The framework was then extended with the capability of examining the performance of novel modifications to the conventional ballasted track. A methodology based on relative settlement was proposed to adapt the results of laboratory element tests into a suitable input into an existing industry-based track geometry degradation model, allowing the estimation of the carbon footprint and Life Cycle Costs (LCC) at the route level. Finally, test results were applied to two practical case studies, demonstrating the capabilities of the model in evaluating and comparing the long-term performance from the inclusion of seven novel track interventions, so as to assess the case for altering current practice.