The management of safety has particular challenges in road tunnels where hazards of moving vehicles carrying loads are significant and the outcome of serious incidents may be significantly affected by human behaviour which can be difficult to predict (Chapter Human factors regarding tunnel safety). A'holistic' approach is necessary to take into account all aspects of the system consisting of the infrastructure, operation, emergency services, road users and vehicles.
The first step in the assessment of requirements is to define the safety objectives. These are normally established at a national level in compliance with national laws, regulations and national standards with safety provisions being a function of the specific characteristics of the tunnel and the associated risk as defined through analysis and evaluation. Risk analysis and the evaluation of the acceptability of risk are addressed in Section Risk assessment of this Manual.
The fundamental principle to be followed is that in the event of an emergency in a tunnel, tunnel users will self-rescue. After the self-rescue phase of an emergency, the fire and rescue services will intervene to fight the fire and assist any remaining tunnel users that are unable to self-rescue.
Safety objectives may be defined in various ways but the work of PIARC, the UNECE and the European Union agree on the broad definition of objectives as being:
Integrated safety for tunnels (Section Safety elements and integrated approach) requires that attention be given to both of these two objectives. Such an approach may be presented as a "safety circle" from pro-action and prevention through to mitigation, intervention and evaluation; and back to pro-action, as shown in Fig. 2.1-1. More information on the objectives and general principles of safety is given in Chapter 3 "General principles" of report 2007R07.Actions aimed at meeting safety objectives and reducing risk may be classified in the following categories:
Information regarding each of the above topics is given in the relevant chapters of this manual as shown above. General information on the choice of safety measures can be found in the following documents:
The aim of safety planning and implementation is to achieve the right balance between the optimal safety level provision and the reasonable construction and operating costs. This may be achieved by taking an integrated approach to tunnel safety (Section Safety elements and integrated approach).