Home | Metrolink Introduction | Telecommunications: created April 2001 | pages list
Metrolink is provided with a comprehensive telecommunication system based on optical fibre transmission and radio links.
Three main communication facilities are required between three groups of people, the control centre, the tram drivers and the passengers who are by far the largest group
Controller to passenger to controller
The optical fibre network is the heart of the telecommunication system it links the Control Centre and stations. There are two types of transmission equipment at each station, the first multiplexes telephone and data circuits, and the second video signals from the closed circuit television (CCTV) cameras. This multiplexed information is transferred to the Control Centre by optical fibre cable link, where it is de-multiplexed and presented to the appropriate control equipment.
The controller can speak directly to passengers at any station by using the station public address system.
An emergency call point, consisting of a call button with microphone and loudspeaker, is provided on each station platform. When a passenger presses the call button, the CCTV picture monitoring that platform call point is displayed in front of the controller, with an indication which passenger emergency call button has been pressed. The controller can then speak directly to the passenger. During this time the picture is being recorded on to a video cassette recorder.
CCTV monitoring is also used for general surveillance of stations including the TVMs and subways (where they exist) and at Hagside level-crossing and the railway tunnels at Heaton Park and Collyhurst. Normally the camera pictures from each camera will be cycling on the bank of the monitors at the control centre in front of the controller. However, at any time, the controller can hold a particular camera picture for close scrutiny or record the picture on to a video cassette recorder.
Controller to driver to controller
Radio links connect tram drivers and other mobile staff with control.
Each tram cab has a radio unit. A network of base-stations are linked to the Control Centre equipment, where the controller has a handset and control unit. Either driver or controller can initiate communication by radio. Each radio channel uses separate frequencies for transmitting and receiving and incorporates address codes, this allows the controller to select individual drivers. Trains can be called selectively or a "fleet call" can be made.
If the radio system should fail or for any other reason, a driver may use the staff telephone provided at each platform and at other key positions along the track to communicate with the controller.
Driver to passenger to driver
Each tram has a public address system which enables the driver to communicate information to the passengers.
In an emergency passengers can request the driver’s attention by pressing the pushbutton on the passenger emergency call unit. This operates in a similar way to the station passenger emergency call unit, the driver is able to respond to the call by communicating directly and discreetly with the passenger.
For passengers, disabled persons intercom–call–units are provided at the wheelchair spaces at a height where a passenger in a wheelchair can easily use them. They allow a disabled passenger to communicate with the driver to ask for assistance or information under non-emergency conditions.
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This page was written by Tony Williams, Manchester Area Officer, Light Rail Transit Association. Contact manwebm@lrta.org if you have any comments, ideas or suggestions about these pages.