If tunnels are longer than a few hundred metres, specific equipment is required to enhance safety to the users, both in normal situations and in case of accidents.
To reduce the risks of accidents and limit the possible consequences, but also to keep an adequate level of comfort to the users, a large variety of equipment can be installed. Chapter 7 of the report 05.06.B "Reduction of operating costs of road tunnels" discusses road tunnel equipment and Chapter 3 of the report 2008R15 "Urban road tunnels" provides details for the design and refurbishment of equipment.
A significant amount of electric power is required to feed the equipment installed in the tunnel. The electrical power supply systems (Section Electrical power supply) must provide enough power in the case of normal and emergency conditions. This also means that the system must work even in the case of blackouts, in order to feed at least the equipment which is absolutely necessary. The status of this equipment should also be monitored. For this reason, a SCADA system (Section Supervisory Control And Data Acquisition systems (SCADA) may be implemented.
A first type of equipment is the communication and alert systems (Section Communication and alert systems). This includes systems used to check periodically the conditions in the tunnel and also to make the operator aware of a possible danger or an accident. Together with systems for surveillance and control of traffic (Section Systems for surveillance and control of traffic), some detection systems can be installed. These include automatic incident detection and smoke/fire detection. This information may also come directly from people involved, through alarm push button or emergency telephones. The latter also allows a communication between people in the tunnel and control personnel. This is useful for the control personnel to have additional information with respect to locations, status of people, etc. but also to supply information to people in the tunnel. This kind of equipment also includes systems used to alert the users in the tunnel or to coordinate the intervention. Loudspeakers and radio-retransmission of public FM broadcasts, frequencies of operators and emergency services can be used for these purposes.
To guarantee comfort to the users and reduce the risks of accident it is important to obtain adequate visibility and reduced concentration of contaminants. For these purposes, an adequate lighting system (Section Lighting) and ventilation system (Section Ventilation) are necessary. Ventilation is also crucial in the case of emergency conditions, as it affects both the fire development and smoke propagation. Depending on the traffic and the tunnel length the ventilation can be only natural, only mechanical or mixed natural/mechanical (i.e. natural in ordinary conditions and mechanical in emergency conditions). An additional element to manage risk is signalling (Section Signposting). This is important in order to highlight possible obstacles or danger, but also to help finding the emergency exits, alarm pushbutton, extinguishers, etc.
In the case of accidents, equipment is required to extinguish fire. This includes fire-fighting equipment available in the tunnel to the users and the emergency teams (Section Fire-fighting equipment for the users and emergency teams) and fixed fire-fighting systems (Section Fixed Fire Fighting Systems), which automatically intervene. In these conditions, barriers (Section Barriers) are important to prevent users outside the tunnel at the time of accident from entering the tunnel.
This Chapter was written by Working Group 1 and Working Group 4 of the C4 committee (2008-2011) in which: