LONDON UNDERGROUND engineers are caught in a constant battle against limited working time to inspect and maintain the Tube's vast network of masonry brick arch structures, a joint meeting of the Institution of Structural Engineers and the Railway Civil Engineers heard last week.
A packed meeting at Great George Street heard LUL's Daya Silva explain that to maintain its 1,500 arches, engineers also had to work around the vast web of power and telecommunications cables now attached to the tunnels.
The meeting discussed the challenges of design, analysis, maintenance strategy and risk assessment of masonry arch railway bridge. According to Kristian Steele from Surrey County Council, this also included the need to consider the environmental impact of repairs.
Steele explained the council's environmental policy was to consider only the most environmentally friendly solutions in masonry repairs. This varies from selection of materials to replacing engineer's 4x4 vehicles with small cars.
Also discussed was the computer modelling technology now available to help engineers analyse whether the vaults supporting stations are adequate.
Bill Harvey of Obvis highlighted Leeds station, where the track and platforms have been altered. The spreadsheet technology enabled him to predict that changes would not alter the loading on the vault enough to render it unstable.