Protecting the UK’s critical infrastructure – impressed current cathodic protection on the midland links motorways network

The Midland Links Motorway Viaducts (MLMV) are located around the UK’s second largest city - Birmingham - and comprise 21 kilometres of elevated bridge motorway structures. Impressed Current Cathodic Protection (ICCP) has been used to prolong the life of more than 700 concrete structures in the MLMV, in a significantly sustainable manner, by reducing the need to remove chloride contaminated (but otherwise structurally sound) concrete. The present study was initiated after identifying that some of the ICCP systems were reaching the end of their design life, whilst others had deteriorated or been vandalised, therefore requiring a significant level of maintenance, and cost. The objective of this work was to collate evidence from field structures to support preliminary laboratory results that the application of ICCP to a reinforced concrete structure over a period of time can transform the protective environment around the reinforcement. The results can indicate when repairs to ICCP systems are likely to be critical; provide new evidence for determining the design life; reduce the requirement to replace systems at the end of their functional life; and the interval between planned maintenance of existing systems may be extended with corresponding reduction in monitoring frequency and costs. The work is unique and novel as it is the only ICCP field trial across Europe on full-scale motorway structures. It also contributes to sustainability as the results form a basis for an improved maintenance strategy.