Cathodic protection on the UK’s Midland Links motorway viaducts

The Midland Links motorway viaducts (MLMV) are a series of reinforced concrete structures comprising 21 km of elevated motorway around the outer circumference of Birmingham. Deterioration was identified early in their serviceable life due to chloride induced corrosion of the steel reinforcement. An electrochemical treatment utilising an impressed current cathodic protection (ICCP) was successfully trialled in 1987 with the first large-scale commercial application of the treatment on the network in 1991. Since then it has been the principal corrosion management strategy for the MLMV, with 740 structures currently protected by ICCP. The aim of this paper is to offer a brief historical review of the MLMV network, discuss the deterioration mechanisms and review the historical developments of ICCP together with its overall performance as a corrosion-management method. Recent developments in cathodic protection technology and secondary beneficial effects of the ICCP previously not recognised are also discussed on how they can potentially result in significant cost savings for maintenance agencies for this and other similarly protected structures.