ABSTRACT
Tunneling in urban areas imposes high construction risks, if unaddressed during the planning and design phases, will result in severe consequences. The overbuilt conditions, the low ground cover, the presence of unchartered utilities and foundations, connections to existing operating systems, etc. exacerbate tunneling risks in urban areas and increase the severity of their consequences. There are unique geotechnical and environmental risks associated with tunneling in urban areas such the potential of mixed ground conditions, presence of boulders and gravel, the presence of old abandoned foundations, the potential of presence of contaminated grounds and ground water, etc. In addition, there are also risks related to public safety, the present of active and abandoned utilities, maintaining surface traffic, maintaining pedestrian movement, impact on businesses and the daily lives of the people. There are also risks associated with construction logistics, material delivery, and equipment, the risk of impact on existing landmarks and historic buildings as well as the potential presence of artifacts and relics. In addition, of the major risks are dealing with project stakeholders, approvals and permitting process, affected communities, and the geopolitical and funding risks.
This paper addresses tunneling risks in urban areas using examples from projects from around the world and mitigation measures.
