Energy saving and economic return on investments for safety and emergency lighting in road tunnels

While planning a double-hole road tunnel with a length higher than a km, it is important to pay attention to the safety factor if an accident occurs. If there is a power outage, in order to avoid critical situations, that could jeopardize the safety of the people present (facilitating the stream coming out from the tunnel and the arrival of the emergency personnel), it is really important to guarantee an uninterrupted lighting of roadways, mandatory emergency lay-bys and ways of escape. An uninterrupted service of the lighting systems supply must be guaranteed, in accordance with the current regulations, through the exertion of UPS and power units. During the tunnel construction such devices represent a costs that must be amortized. In this case study, which takes into consideration a section of a road tunnel characterized by emergency lay-bys and ways of escape, emergency and security lighting were planned and installation and management costs were evaluated. In order to have a cash flow where the service life of the system coincided with the amortization of the costs of the backup electrical equipment installation, it was taken into consideration the possibility of overdimensioning the UPS and providing it with a proper photovoltaic panels surface to generate and exchange electric energy with the grid.