This group comprises cross-functional equipment:
A significant amount of electric power is required to enable the equipment installed in the tunnel to operate. The electrical power supply systems (see page on Electrical power supply) must provide enough power for normal and emergency conditions. This also means that the system must work even in the case of blackouts, enabling vital equipment to keep functioning.
To guarantee user comfort and reduce the risks of accidents it is important to ensure adequate visibility and reduced concentration of contaminants. For these purposes, an adequate lighting system (see page on Tunnel lighting system) and ventilation system (see page on Tunnel ventilation system) are necessary. Ventilation is also crucial in emergency conditions, as it affects both fire development and smoke propagation. Depending on the traffic and the tunnel length, ventilation can be only natural, only mechanical or mixed natural/mechanical (e.g. natural in ordinary conditions and mechanical in emergency conditions).
The status of this equipment should also be monitored. For this reason, a SCADA system (see page on Supervisory Control And Data Acquisition systems (SCADA)) may be implemented.