The tunnel radio system is used to establish radio connections between radio stations inside the tunnel, as well as between tunnel radio stations and external radio stations and control centers.
The primary purpose of the system is to provide radio communications for safety services, but it also enables rebroadcasting of public radio programs and the provision of any necessary information to users listening to those programs while driving through the tunnel.
The tunnel radio system consists of a central radio frequency station in the tunnel control center, tunnel amplifier substations, and an antenna and cable system.
A radiating cable is used as a receiving and transmitting antenna in the tunnel. It is a special type of coaxial cable with openings of a specific shape and arrangement on its outer conductor, allowing for radial radiation.
To connect the tunnel amplifier substations with the central RF station, single-mode fiber optic cables are used.