The objective of this project was to stabilise and remediate a section of the King’s Scholars’ Pond Sewer (KSP) that spans the crown of the London Underground tunnel. This required the construction of a 9.5m long Vierendeel truss and associated glass fibre reinforced plastic (GFRP) liner. The modular structure was designed to be installed through the aperture of an existing manhole and then bolted together to form a watertight bridge within the existing sewer and spanning the London Underground tunnel beneath.
The King’s Scholars’ Pond Sewer is a brick sewer constructed in the 1850’s and following the route of the River Tyburn. At the station it crosses approximately 3m below busy main arterial road and bridges the crown of the London Underground tunnel. At this location the sewer is supported by two primary cast iron beams, which span between pad-stones embedded within the brick wall of the railway tunnel. Between these two primary beams are profiled cast iron invert plates connected back to the beams by bolted connections. A brick crown completes the sewer profile.