CONTRACTOR GEOFFREY Osborne is nearing completion of a £1.1M pedestrian subway in Surrey that is being built with train services in operation.
The subway, in Ash Vale, Guildford, is 8m below the tracks which carry the Guildford to Reading and Aldershot Spur lines.
Osborne has jacked interlocked steel beams through the rail embankment 800mm beneath the track to form a temporary roof lining. Further steel beams were then impact rammed to create temporary side walls.
Once in place, steel frames were progressively installed for support as soil was mined out.
The permanent concrete subway is now being formed inside the steel structure.
Engineering director Derek Hughes said: 'The pre-installed beam lining was made using beams that were small enough to avoid track heave or risk dragging the tracks horizontally, but robust enough to ensure there was minimal deflection when they were loaded during the mining operations and when trains went over them.'