The approach for the development of a safe system is not the simple adoption of all possible safety measures but is the consequence of a balance between the forecast risk factors and the safety measures.
With the establishment and development of international regulations, recommendations and guidelines, there is a need for a framework within which all aspects of tunnel safety are taken into account. Such a framework may contain the following principal elements:
These safety elements are described in the Chapter 5 "Elements in an integrated approach" of report 2007R07, "Integrated Approach to Road Tunnel Safety".
Figure 1: Integrated approach
An integrated approach is a framework to plan, design, construct and operate a new tunnel or an upgrade to an existing tunnel, fulfilling the required safety levels at each stage of the tunnel life. This should take place in accordance with a safety plan, following the appropriate safety procedures.
Fig. 1 shows a schematic representation of a proposed integrated approach for the safety of new and in-service tunnels, comprising the elements listed above. For more information, see Chapter 6 "Conclusion" of report 2007R07 and chapter 1 and chapter 7 of report 2016R35 which respectively address experience with the integrated approach.