Experience shows that a kilometre in tunnel is always more costly than a kilometre of the same road outside. In the case of an underground structure, we can find several systems and equipment that are deployed either for ensuring a safe operation under standard operating conditions or for allowing the protection and the evacuation of users and the intervention of rescue services in case of incident, accident or fire. These measures not only represent considerable investment costs but also result in particularly high costs for operation and maintenance. Thereby the role of the operator is to ensure the continuity and the safety of the operation in a context of controlled costs.
In all cases, even a high standard of tunnel operation may not allow an optimisation of operational costs, if the design and the construction of the tunnel have undertaken to a low quality level. The operational costs therefore need to be a major concern during the different phases of the project and the work execution, considering that the solution need to be found well before becoming an issue during the operational phase.
The operation activity has to be designed at an adequate level in order to ensure that the expected lifecycle of the equipment does not decrease. The lifecycle of equipment in tunnels is normally shorter than in other environments, since the atmosphere in tunnels particularly corrosive.
The Technical Report 05.06.B "Road Tunnels: reduction of Operating Costs" is entirely devoted to operating costs and in particular, to reducing them.