The welfare costs of weather related disruption on the transport network have been estimated to be between £100m and £520m per day of disruption in England. This paper presents a case study of a mainline railway cutting and tunnel, which is situated in the catchment of a significant river and is susceptible to flooding. The project evaluated the benefits of using combined ‘blue-green-grey infrastructure’ schemes (respectively, use of floodplains and wetlands; use of sustainable drainage; and use of traditional drainage infrastructure) to increase the railway network’s resilience to flooding events.
The policy perspective on valuing transport network resilience to extreme weather is briefly examined first. The wider economic costs of tunnel closure are then estimated using standard transport analysis guidance procedures. The calculation illustrates the potential magnitude of costs relating to rail network disruption at the tunnel (£264,000 per day of tunnel closure), and is used to frame a discussion of the limitations of current appraisal methodologies with respect to capturing the wider dis-benefits of inadequate network resilience.
The discussion is then broadened to critically examine the nature of the ‘flooding problem’. Who are the stakeholders in the ‘flooding problem’ (Network Rail, landowners, housing developers, local authorities, the local community) and what are their vested interests in whether and how ‘the problem’ is solved? Example blue-green-grey schemes developed through the case study are used to identify how their collective interests might best be served through alternative approaches to flood risk management. Finally, the extent to which traditional approaches to transport option appraisals enable, or preclude, the delivery of such innovative schemes is discussed. Can collaborative approaches to decision-making be developed that lead to shared ownership of the ‘flooding problem’, and does consideration of ecosystem services offer greater potential for the development of innovative, multi-benefit and cost-effective schemes?