Technical inspections

The equipment of a tunnel is highly varied. From electromechanical equipment (power supply, ventilation, lighting ...), to operating equipment using more recent technologies (video surveillance, SCADA, automatic incident detection...), it requires more or less frequent interventions to maintain functionalities.

Interventions to be performed on equipment can be grouped into three broad categories:

• Maintenance,
• Control,
• Renewal.

Maintenance can be defined as a set of actions that maintain equipment in a specified state, restore it to this state or ensure that it can provide a specific service. These actions can be preventive in nature (referred to as preventive maintenance) or remedial (corrective maintenance).

Maintenance control, in the broadest sense, aims at ensuring that the maintenance actions carried out allow satisfactory operation of the equipment and that the financial resources allocated are adapted to requirements.

An assessment can be carried out by conducting technical inspections at specified periods:  

• at commissioning of the equipment (initial inspection),
• during the tunnel operation phase (periodic inspections).

The initial inspection must be carried out before equipment is put into operation. It aims, on the one hand, to check the quality and performance of the installations and, on the other hand, to ensure that the tunnel and its equipment comply with regulations, in particular with regard to safety.

The initial inspection, which provides a reference on the condition and performance of the tunnel at commissioning, should be followed by further inspections throughout the tunnel’s life. These inspections must be carried out periodically at an interval that may vary from one country to another, but which is, in most cases, of the order of several years.

The results obtained during these various inspections therefore make it possible to verify that maintenance is well adapted and that the expenditure and financial budget  makes it possible to achieve the objectives set.

When the equipment approaches the end of its life, these inspections also enable refurbishment or renewal actions to be planned.

Further information on technical inspections can be found in technical report 2012R12EN: Recommendations on management of maintenance and technical inspection of road tunnels.