Expected Climate Loads for the West Coast Main Line (until 2050ies)
1) Temperature changes
The expected changes of the average temperature until the 2050ies for Western England and Scotland are +2° like in most European regions. The expected increase for the warmest days is more pronounced – up to +4° - which increases the likelihood of extremely hot days and heat waves quite considerably.
The following figure shows the expected changes in the maximum temperature in summer for a medium emission scenario, based on calculations within the framework of the UK climate projections 2009.
The projected changes in precipitation are most significant for the winter season. In general wetter winters are to be expected with an average increase of precipitation around 20%. In some locations, an increase of over 30% is likely.
The University of East Anglia in Norwich and the University of Newcastle, UK, performed a study investigating possible changes in extreme rainfall across the UK until 2070/2100. The results show, that that for short duration events (1–2 days), the event magnitude at a given return period will increase by 10% across the UK. For longer duration extreme rainfall events (5–10 days), event magnitudes show high increases of up to 30% especially in Scotland.
Future weather will not only have wetter winters, but most likely also be characterized by more extreme rainfall events and, thus, significantly increase the risk of surface and fluvial flooding.
3) Storms and Gales
With current regional climate models, the modelling of storm intensities and return periods is much more difficult and controversial than modelling of temperature and precipitation distributions. Nevertheless, there are some indicators suggesting an increasing number of severe storms for the mid-term future. In a study of AIR Worldwide Corp. and the Met Office undertaken for ABI in 2009, the consequences of a 1.45° southward shift in storm track across the UK were analysed. It was found that under these assumptions the average annual insured wind losses in the UK could rise by 25% to £827 million. At the regional level, increases range from 17% to 29% as can be seen in the following figure.
Past extreme weather events
An overview over past extreme weather events which have heavily affected the operation of railway infrastructure and even the integrity of infrastructure assets is given in the following list:
Vulnerability Study for the West Coast Main Line
a) Screening Process
Within the framework of the first phase of the project Tomorrow's Railway and Climate Change Adaptation (TRaCCA) Network Rail investigated the most relevant weather and climate related factors and their impact on railway infrastructure assets. This screening process involved seven workshops with the participation of railway asset management specialists from Network Rail from the Engineering, Operations and Maintenance departments as well as experts from ATOC. Taking in to account the effects of projected climate change, potential risks to the railway were identified. The outcome of the workshops was further qualified by an expert review and moderation exercise which especially focused on prioritising the findings.
In a second feedback round the summary list of priorities from the review and moderation exercise commented, modified and finally confirmed by the experts. The results of this process is a table of risks structured by climate impact groups and infrastructure clusters that are likely to pose the greatest threat to the railways, taking into account the impact of climate change. These 'priority topic areas' in respect of the impact of climate change on performance and safety of railways are shown in the following table.
b) Analysis of current and future vulnerabilities
In the next phase of the TRaCCA project, Network Rail will investigate the priority topic areas in respect of the impact of climate change on performance and safety of railways in more detail. This will be done by modelling the most important hazards such as extensive heat and heat waves, river and surface flooding, landslips and storm throw for the West Coast Main Line and assessing the impact of these events on the different railway infrastructure assets. As a result of this assessment, vulnerability maps for the West Coast Main Line will be developed.
In addition to vulnerability maps, the second phase of TRaCCa will generate the following output:
c) Measures for the improvement of infrastructure robustness will be identified and discussed in detail.