The construction and operation of a new light rail transit or metro system in an urban landscape presents a series of corrosion risks to an often densely-packed buried infrastructure. Structures at risk from stray current include the rails, rail infrastructure, buried utility infrastructure such as pipelines, cables and building infrastructure such as steel sheet piles and structural steel work. Design issues that impact on stray current are often wrongly set with the initial design of the system - constrained by factors like electric power and land availability and the desire to limit the initial costs of a project. This has often led to severe stray current damage and serious transit systems management failures. Developing stray current models of transit systems at the design stage can be an invaluable tool to optimise the design. The models allow for the calculation of stray current effects at a rail, rail infrastructure - tunnels bridges - and at third party infrastructure level and helps to drive design decisions. In this paper a series of stray current and corrosion software models were constructed to study the impact of stray current leakage from a proposed transit system on the surrounding infrastructure and used to test the effect of different design solutions and mitigation methods on the infrastructure. Transit operating data were used in conjunction with soil and structure data gathered from site measurements to predict the corrosion impact.
Keywords: corrosion, corrosion control, current distribution, electric field, modelling, rail, stray current, steel sheet piles