Frequently asked questions
What are the main risks in road tunnels?
This section only refers to risks to users travelling through tunnels, not risks during construction.
The first type of risk is related to the instability of the structure and the equipment attached to the tunnel arch. Regular monitoring and maintenance provide complete protection against these risks.
Malfunctioning lighting or ventilation can affect user comfort and even cause discomfort (due to poor visibility and toxic air).
Risk-generating events such as breakdowns, incidents, accidents and fires can have serious consequences due to the confined nature of the tunnel. The vast majority of fires are caused by spontaneous vehicle ignition due to technical failure, but all of the rare fires that have resulted in fatalities have been the result of an accident, with the exception of the 1999 fire in the Mont Blanc tunnel.
Fires involving heavy goods vehicles are the most feared event in tunnels. It is on this scenario that designers and operators focus all their attention.
The effects of a fire occur in the following order:
- the arrival of smoke, which is highly opaque and incapacitating, considerably hinders the evacuation of users,
- users who have been unable to evacuate due to poor visibility are inconvenienced or even asphyxiated by the smoke, which becomes increasingly toxic,
- the heat released by the fire causes high temperatures.
Local authorities have no control over vehicle design, but they can prohibit or regulate the passage of certain vehicles, such as those transporting dangerous goods.
Infrastructure refers to the geometric characteristics and structural elements of the tunnel (including emergency exits), and all technical equipment (power supply, lighting, ventilation, detection, radio communications, signalling, etc.).
The degree of tunnel supervision varies greatly depending on the tunnel, ranging from no supervision to highly sophisticated supervision where the operator, thanks to the information provided (including automatic incident detection), is able to act very quickly:
- inform users and encourage them to adopt the most appropriate behaviour,
- alert the emergency services (with a particular focus on the fire brigade, whose speed of response determines the chances of controlling and extinguishing the fire),
- take action using the available equipment (tunnel closure, activation of the smoke extraction system, etc.), and call in specialised operational teams to intervene on site.
It is important to emphasise the essential role played by user behaviour. Before the emergency services have time to arrive on the scene, users are alone in the tunnel. Their behaviour, and in particular their responsiveness in the first few minutes after the initial event, is a determining factor in safety. This explains the efforts made to provide equipment to guide users in difficulty.
How can user safety be ensured?
What are the current principles applied regarding tunnel safety?
The threshold, set by national regulations, corresponding to the length above which the safety issues specific to tunnels require special provisions is 300 m.
Each of these tunnels must undergo a detailed diagnosis and analysis, all of which is compiled in safety documentation submitted to a committee of experts independent of the tunnel operator.
This documentation involves all parties involved in the event of an incident (operators, fire brigade, law enforcement, etc.) and describes the actions to be taken for each type of incident that may occur. It also assesses the likely consequences of these incidents and the expected functioning of equipment and emergency services.
Is there a list specifying the conditions for the transit of dangerous goods in each French road tunnel?
A non-exhaustive list covering only tunnels longer than 300 m can be downloaded below.
This list contains information on the rules governing the transport of dangerous goods in tunnels, as defined in the Highway Code (specifically, tunnels longer than 300 metres).
The CETU database from which this list is derived is updated as regularly as possible on the basis of the information provided. However, the transmission of information relating to the transport of dangerous goods to
CETU by the operator or project owner is not mandatory. Consequently, this list cannot be considered exhaustive and the data it contains is not guaranteed. It is primarily intended for statistical purposes.
When the classification has been communicated to CETU, it appears in the table in the following form: category A, B, C, D or E. When this classification has not been communicated, the information attached to the tunnel
is that which was available before the tunnel categories for the transport of dangerous goods came into force (1st January 2010).
When preparing the route, it is the carrier’s responsibility to obtain information on a case-by-case basis on the rules governing tunnels in relation to dangerous goods, based on the official documents governing them
(regulations or traffic orders).