Formal risk management has become an important tool in many technical fields and is being more widely accepted by the tunnel and underground industry. Indeed, guidelines for systematic risk management published by the International Tunnelling Association have become a standard for the industry. The insurance industry, especially the re-insurance industry, is very actively promoting risk management at all stages of a project in order to minimize insurance losses. Urban mechanized tunnelling can be associated with a series of risks and the principal risks generally derive from the uncertainties and hazards associated with the geological, hydrogeological, and construction conditions or parameters, plus the political and/or public opinion constraints that require special attention. The Designer should be able to manage all kind of design risks related to geology, hydrogeology, load conditions, construction method and all physical and environmental impacts both surface and subsurface, from the conceptual design to the follow-up of the construction.