Optimizing the operating costs of a tunnel and in particular those related to energy consumption, is a task that must be undertaken from the early stages of the tunnel design. PIARC has shown that a significant part of operating costs is determined by the choices made during the design and implementation phases (Report 05.13.B Good practice for the operation and maintenance of road tunnels).
It is also important to adopt a global approach that takes into consideration the three pillars of sustainable development: societal, environment and economic (report 2017R02EN: Road tunnel operations: First steps towards a sustainable approach). More specifically, it is important to avoid implementing a solution that is advantageous in terms of initial investment, but which entails an excessive annual energy consumption.
This naturally leads to applying an approach based on the cost of tunnel ownership as a whole, taking into account not only the initial cost of equipment, but also operating costs throughout the tunnel’s expected lifetime (Report 2016R01EN Best practice for life cycle analysis for tunnel equipment).
As the equipment present in tunnels is numerous, diverse and has lifespans that vary considerably from one type to another, it is often more efficient to conduct a specific optimization approach for each large family of equipment.
Finally, although, as we have said, the optimization work must be started during the initial design phases, the technical provisions chosen and the equipment implemented require constant monitoring, if they are to maintain their performances over time. Regular and thorough maintenance is therefore necessary so that all the actions undertaken to optimize the energy consumption of a tunnel remain efficient (Report 05.13.B Good practice for the operation and maintenance of road tunnels).