The waterproofing of sprayed concrete tunnel linings has traditionally been carried out using sheet membranes encased between the sprayed concrete primary lining and a cast in situ secondary lining. While this method is acceptable for linear tunnel construction, it is less suitable for complex geometrical shapes such as junctions.

Working in close collaboration with the specialist waterproofing company Stirling Lloyd an effective sprayable waterproofing system was developed that can significantly improves productivity, particularly on projects with complex geometry