signalling & telecoms


july 2010 | the rail engineer | 35


Clive Kessell reports Lifeblood To many railway staff, the


telecommunications applications that enable operations and business are akin to water in the tap - taken for granted with little thought given as to how the systems or the supporting designs are provided. Yet behind this perception is a complex network of integrated bearers and complex end-user applications. The Docklands Light Railway (DLR) is no


exception and is as dependent on telecoms as any other main line or metro operation. DLR opened in 1987 and, in that time, telecom technology has moved on apace. The early systems were replaced a while ago but, with the continuing expansion of routes and train services, a step-change modernisation of the telecom assets has been taking place over the past five years.


The asset portfolio DLR has an amazing number of telecom


systems and applications, probably more than any comparable light rail operation. The list is long - • fibre and copper cables • the ‘Open Transport Network’ transmission bearer


• a high speed LAN providing Ethernet and IP services


• telephone exchanges and extension telephones


• UHF control-to-train radio, recently transfusion upgraded to provide improved coverage


• CCTV surveillance of stations and depots including digital video recording


• Long line public address (LLPA) - more accurately, a total railway-wide PA network


• synthesised voice announcements and message construction


• local PA facilities at stations • passenger emergency points (PEP) at every station


• ‘next train’ displays on platforms, driven from the signalling system


• train running information displays on concourses and other public locations, known as DAISY - Docklands Arrival Information System


• on-train CCTV surveillance with linkage to the control room


• a SCADA network for traction power control and fire alarm management


• an emergency power cut-off override system


• central time system for time and date stamp on all recordings


• automatic passenger count facilities at stations


• Oyster ticket validation data management • ticket vending machine data capture • tunnel communication systems including radiating cable and ‘blue light’ telephones


• control room concentrators, telephones and maintenance aids.


Not all the end applications are the direct


responsibility of the telecom group but the bearer networks ensure that they are all ‘glued’ together and sensibly integrated. The situation is further complicated in that DLR has expanded piecemeal over the years with different types/marques of equipment being supplied for the newer routes. This article details the provision of three new systems, explaining the design, contract arrangements and implementation.


The bearer networks For some years now, DLR has invested in


the OTN (Open Transport Network), developed in the 1990s by Siemens for both oil & gas and metro industry applications. Designed to operate in ring architecture, the systems come with varying capacity according to traffic and application. Similar to standard SDH (Synchronous Digital Hierarchy) technology, the OTN family has different speed and coding characteristics that make it a bespoke system.


A concourse screen and help point.


PHOTO: TOMPAGENET


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