Tunnels, initially aimed at crossing an obstacle (in general a mountain), have become increasingly complex during recent years, incorporating increasingly complex equipment (including ventilation systems) and methods of operation. Such operation includes the deployment of control and supervision systems that able to handle tens of thousands of items to be controlled, and which can accommodate increasingly sophisticated management scenarios.
Following the catastrophes at the Mont Blanc, Tauern and Gothard tunnels in the years 1999 and 2001, the need for recognising all aspects relating to safety as a holistic system was reinforced. This resulted in the integration, from the design of the works onwards, of more constraining provisions, which have an important impact on the required civil engineering and the specified tunnel equipment.
Tunnels are in general considered as "expensive and risky" works, both with regards to their construction as well as their operation. This "image" makes some countries very reluctant when considering the construction of their first tunnel for their road or railway infrastructure. In order to address such concerns, it is inevitable that the costs of construction and operation, the control of risks (mainly during the construction phase), the minimisation of accidents or fires during the operation and the optimisation of the tunnel facilities at each stage of the design, construction and operation become increasingly necessary. This control of the risks and the costs is reinforced when considering current procurement and financing models for the construction of tunnels, which are increasingly being implemented as "Concession", "Design and Build" or "Private Public Partnership" models.
Chapter Strategic issues of this manual has the following aims:
It is not the intention for this Chapter to be a detailed handbook of the actions required by tunnel owners, or to specify the technical provisions to be implemented by the designers, or to determine the tasks to be taken by the operators to ensure a safe and comfortable tunnel. In particular, Chapter 1 does not have an objective to be a handbook of design. Its only objective is to make the reader aware of certain issues, in order to facilitate his approach and comprehension of this complex field, to hopefully enable him to avoid the many possible errors in tunnel operations, and to enable him to perceive the possibilities of optimisation.
Section Tunnel is a complex system presents the "complex system" that a tunnel is, and lists the main interfaces of the various subsets Civil Engineering, Ventilation and Safety;
Section General design of the tunnel (new tunnel) presents the major elements which have to be considered when designing a tunnel;
Section Renovation - Upgrading of existing tunnel concerns the upgrading and the refurbishment of existing tunnels under operation;
Section Stages of the “tunnel life” analyses various stages of the cycle of construction and the life cycle, and underlines the key actions of each one of these phases;
Section Costs of construction - Operation - Upgrading - Financial aspects explains issues relating to the costs of construction, operation and renovation, as well as the main stakes specific to the modes of financing;
Section Regulations - Recommendations gives a list of the main recommendations, instructions and regulations published by a number of countries in Europe and in the world.
Section Complex underground road networks is a case study of complex tunnels and presents numerous monographs.
This document was compiled by Bernard Falconnat (Egis, France), French representative in the Road Tunnels Operation Committee and member of Working Group 5, which has also translated his French version into the present English version.
Its original version in French was revised by Didier Lacroix (France) and Willy De Lathauwer (Belgium – ITA representative within the committee).
The English version has been reviewed by Lucy Rew (Egis, France) and Fathi Tarada (UK).