A risk-based approach to the management of upland highways: A628 case study

摘要

The A628 trans-Pennine highway is a single carriageway trunk road of largely Victorian design that provides a strategic relief route between Manchester and South Yorkshire when the M62 motorway is closed. The route section within the Longdendale valley on the western flank of the Pennine ridge has been subject to significant disruption in recent years due to landslides that have generally occurred at locations with pre-existing ground instability, highway/land drainage problems or both. The landslides appear to have been mainly triggered by intense rainfall events. Given the widely-held view that on-going climate change will result in an increased incidence of high intensity rainfall events and associated ground instability in the United Kingdom over the next 50 years, a strategic review of ground instability-related risks to the A628 was undertaken in order that an integrated and sustainable approach to highway management could be developed. Given the restricted nature of the risk assessment approach routinely applied to ground instability-related risk assessment on the trunk road network in England (i.e. HA standard HD 41/03), a bespoke risk assessment procedure was developed for the purposes of the A628 Strategic Study. The innovative aspect of the approach is that hazards to the route from both the highway earthworks and the wider natural landscape lying beyond the highway boundary were considered together in order to generate comparable risk data for both aspects. This paper describes that bespoke hazard and risk assessment, identifies the various datasets informing the study and summarises the study findings and recommendations.