Abstract
Infrastructure operators are facing the challenges of managing assets under pressures from reduced budgets, aging infrastructure and increasing travel demand. This happens in the context uncertain climate change prompting the need for ever more robust and flexible decision support tools. One major risk to bridges in both current and future climate conditions is bridge scour- the removal of riverbed material at bridge foundations due to the flow of water. Scour is the foremost cause of bridge failure both in the UK and worldwide. This thesis explores climate change impacts on the management of scour risk for national bridge stocks. To do this a selection of methods is compiled to model the chain of processes linking climate change to scour risk at a network level, exploring the role of key uncertainties. One main research finding is that the current scour assessment techniques used in Network Rail may be insensitive to the effects of climate change. This is a result of a number of factors, including the use of over-conservative models, exceedance probabilities and safety factors. This conservatism is not well understood and leads to the reduced ability of Network Rail to objectively assess bridge scour risk at a network level, which has repercussions both in the context of current and future climate. Another key finding is that climate change uncertainty, which is largely aleatory, may in some cases be overshadowed by asset uncertainties, which can be reduced. Some model inputs, such as floodplain width and abutment width, are found to be both subjected to high uncertainty and also influential for the estimation of scour risk, leading to reduction in the confidence in scour risk assessments. Understanding model sensitivities and the relevant uncertainties would enable bridge operators to improve the quality of scour risk assessments by improving the quality of relevant data. This thesis makes a number of key recommendations that will enable Network Rail and other bridge stock managers to effectively adapt scour risk management practices for national bridge stocks to climate change.