Maintenance

This chapter gives information on the general principles of maintenance, technical inspections and life cycles. Some information related to complex tunnels, civil works and winter maintenance is also given.

Structural elements and the technical equipment need regular maintenance, the aim of which is to ensure safe driving conditions for the public by keeping the tunnel at its designed safety standard (see page on Maintenance of equipment). General recommendations for maintenance in tunnels are defined as well as the specific features and their facilities.

Life cycle or Life Cycle Cost (LCC) aspects are becoming increasingly important. From an economic point of view, it is important to consider these aspects both in the design and in the operation of tunnel equipment (see page on Life cycle of tunnel equipment).

It is important to verify that the maintenance actions conducted have enabled the pre-defined objectives to be achieved. These verifications take the form of technical inspections, their aim being to make sure that the maintenance actions carried out allow the equipment to function in a satisfactory manner and that the frequency of maintenance actions is adequate (see page on Technical inspections).

The technical report Good Practices in Maintenance and Traffic Operation of Heavily Trafficked Urban Road Tunnels - Collection of Case Studies provides a collection of case studies to gather, evaluate and comment on international expertise related to maintenance and traffic management in highly trafficked urban road tunnels. A large number of cases provided an insight into the implementation of these special requirements for urban road tunnels.

Although maintenance actions on a “Complex underground road network” are essentially similar to those on a typical road tunnel, they are more complex due to:

• the complexity of operating systems often built at various times, with many disparities in technology and aging. This requires a very good knowledge of the equipment on the part of the maintenance teams, the management of more diversified spare-parts packages, and a special vigilance regarding obsolescence,
• systems that can be overall more sensitive and less reliable because of their multiplicity, their technological diversity, their interactivity and their ages,
• traffic volumes that limit the periods of intervention and their durations.
• the necessary coordination with all operators of the other connected infrastructure, whether underground or in the open air.

The special recommendations concerning the maintenance of an "underground road network" are presented on the page "Maintenance of complex tunnels“.

In some countries, and not only in mountainous areas but also in very cold areas, winter maintenance can be quite a challenge in maintaining the tunnel functional and safe or in implementing new electronical and mechanical equipment’s and technologies (see the page on Winter maintenance)

Civil engineering structures within the tunnel also need regular monitoring and inspections. It is necessary to carry out regular maintenance of facilities such as drainage systems, gutters and all secondary structures (premises inside the tunnel, technical rooms, etc.), For further information, please consult the page on “Civil Works”.