Flood Risk to the Strategic Road Network in England Barry Hankin

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(1)E3S Web of Conferences 7, 10001 (2016) FLOODrisk 2016 - 3rd European Conference on Flood Risk Management. DOI: 10.1051/ e3sconf/2016 0710001. Flood Risk to the Strategic Road Network in England 1,a. 1. 2. 3. 3. Barry Hankin , Iain Craigen , Will Rogers , Joanne Morphet , Andy Bailey , Michael Whitehead. 3. 1. JBA Consulting, Bank Quay House, Sankey St, Warrington, WA1 1NN AECOM, AECOM, URS House, Horne Lane, Bedford, MK40 1TS Highways England, Woodlands, Manton Lane, Bedford, MK41 7LW. 2. 3. Abstract. It is vital that flood risks from multiple sources to the national Strategic Road Network are well understood, to help minimise disruption, reduce risk to people and to help prioritise maintenance programmes. Highways England have undertaken research to update their current understanding of risk based on improved flood mapping,

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(8) vents, severity and causes over the last 5 years. Building on the previous risk assessment, the roads layer was interrogated against new flood hazard data for multiple sources of flooding. The road network was divided into 100m segments in order to capture a strong spatial understanding of predicted flood risk from each source, but also summarised on a 1km scale and a management area level to aid prioritisation at varying scales. The 1 km grids were then ranked across England according to each source of flooding, and also an overall rank was derived through summing these ranks together. This was validated against

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(11) recorded by Highways England, based on over 12,300 records, collected over 5 years.. 1 Introduction With an increasing number of high profile flooding events making headlines around Europe, there is a greater awareness of the cost in terms of damage, disruption and casualties. Estimates for the UK 2007 summer flooding alone put road reparation costs at £190m, and disruption costs at £98m, albeit highly uncertain [1]. The UK DfT recently announced emergency road reparation funds of £40m in the wake of UK storms Desmond and Eva for Cumbria and Lancashire. This paper reports on an updated national screening assessment of the predicted flood risk to Highways England's Strategic Road Network (SRN) which spans all trunk roads including the slip roads to and from trunk roads within England. Figure 1 illustrates the Highways Agency Pavement Management System (HAPMS) which has been used to define the SRN across the study area. The study area shows the Highways England Management Areas (MAs). Predicted flood risk to the SRN from each source has been scored for the carriageway split into 100m segments following a technique developed for the Irish Roads Authority [2]. Each flood risk source score has then been summarised within 1km grid squares as well as combining all sources to produce both weighted and unweighted overall flood risk ranks which can be used to prioritise maintenance and management. These modelled high priority risk areas were then compared against

(12) further below. This is based on approximately 12,300 a. individual road flooding incidents, collected by the 14 MAs since 2000, but in a systematic way for 5 years. A suite of interactive PDF maps were produced to present the national screening assessment at both the Management Area and 1km grid square scales. These are to strategically identify vulnerabilities in the national network as recommended in the European Roads Authority Network (ERANET) RIMAROCC procedure [3] and improve the prioritisation of flood risk management measures from warning to maintenance.. Figure 1. Highways England Strategic Road Network and Management Areas.. Corresponding author: [email protected]. © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/)..

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