Evaluation of risk assessment procedures for buildings adjacent to tunnelling works

Risk assessment procedures for underground projects form a key component of pre-construction efforts since resulting ground movements may cause damage to adjacent structures. Particularly for urban tunnelling works, surface settlements may impinge on a vast number of structures and can result in significant lawsuits unless the appropriate building protection measures are implemented. Although the understanding of tunnelling induced building damage has advanced greatly in recent decades, damage and litigation persist. Hence, this paper reconsiders the pre-construction risk assessment procedures undertaken during the generation of an Environmental Impact Statement (EIS) by formally including considerations relating to a building's historical significance, present usage, and current physical condition. In doing so, a holistic approach to risk assessment is proposed, allowing for project resources to be targeted towards buildings that are most at risk. This is demonstrated through a Class A prediction for a section of an upcoming underground railway system in which 14% of the selected study area of 220 buildings are identified to be at risk. Results are compared to those produced by the official EIS where building vulnerabilities are considered in isolation from the damage prediction assessment and just 5% of buildings are considered to be at risk. The proposed methodology offers a standardised procedure for incorporating both cultural and physical aspects of each building, thereby providing a more systematic, comprehensive procedure for pre-construction risk assessment than previously available.