MODELLING THE IMPACT OF STRAY CURRENT
Threading new railways through complex urban environments presents new corrosion risks to existing infrastructure owners. In this case the owner of a large £500M office, leisure and retail complex constructed on a brownfield site making significant use of large sheet steel supporting walls needed assurances of the corrosion impact of a proposed tramway adjacent to the walls and design guidance on mitigation and tramway specification measures to minimise the risks. This was accomplished through the creation of a geometrically accurate electrical model of the site – covering the supporting walls, utilities and buildings in addition to the railway - that demonstrated soil potential gradients and the resultant current flows allowing the corrosion damage to be calculated over the remnant design life of the asset.
The models demonstrated the relative detrimental impacts of different tramway designs to be assessed and led directly to the creation of a design specification for the tramway and design guidelines for stray current control to be applied to all future infrastructure at the site. The benefits for the owner were the assurance of future asset integrity and the avoidance of remedial mitigation actions such as cathodic protection.
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