A leaky feeder is a communications system used in
underground miningand other tunnel environments. It consists of a cablerun along drivages which emits and receives radio waves. The system has a limited range and because of the high frequencyit uses, transmissions cannot pass through solid rock, which limits the system to a line of sightapplication. It does, however, allow two-way mobile communication.
This system is also used for underground mobile communication in
mass transit railways. In Hong Kongthe leaky feeder aerial was incorporated in the specification of the capital project and installed during construction. This allows emergency services seamless mobile communication from the underground to the surface.
London, London Undergrounduse a leaky feeder system for their internal communication network. The emergency services' communications system however is not compatible and does not work underground. That this situation continued to exist after the 1987 King's Cross firewas criticised in reports into the 7 July 2005 London bombings, where it hampered rescue efforts.
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