Section 19: Signs associated with Radio Systems
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An in-cab radio system was a safety requirement for the introduction of "Driver Only Operation" (DOO), meaning the working of trains without a guard. The radio allows the driver to remain in the cab and communicate with the signalman when stopped at a signal, rather than using the signal post telephone. The system is secure, in that the driver and signalman can communicate on a one to one basis and not be heard by anyone else. The signalman has the facility to transmit a general message to all drivers in a particular area.
The system was first applied in the Glasgow area in the late 1970s, being referred to originally as the "Strathclyde Manning Arrangement" (SMA). Subsequently, the same system was put in place in the Liverpool and London areas, and the general term "Cab Secure Radio" (CSR) was used.
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A separate radio channel is used for each area under the control of a particular signalman. Channel changes are normally performed automatically, but lineside signs displaying the channel code are provided at the boundary from one radio zone to the next, and at places where the 'set up' procedure is usually carried out [19.1].
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[19.1] Radio Channel Indicator (original design).
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Radio systems were installed on some lines in the north of Scotland in the early 1980s in preparation for the eventual introduction of Radio Electronic Token Block (RETB) signalling. Some rather basic signs were installed at the places where the channel had to be changed [19.2 & 19.3]. When the Regional Operations Manager travelled over the Inverness - Aberdeen line in 1985, he saw what he referred to as "painted bits of wood with radio channel change information on them". He demanded that they be changed to circular or octagonal boards with yellow letters on a blue background, but they never were.
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[19.2] Channel Change Board (Dingwall - Kyle of Lochalsh line).
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[19.3] Channel Change Board (Inverness - Aberdeen line).
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The National Radio Network (NRN) originated around 1980. Originally used only by engineering staff on the lineside, by the mid 1980s it was in widespread use in driving cabs. The train driver may use the system to access the railway telephone network from inside the cab. NRN is not a 'secure' system like CSR. The need for lineside electrification telephones ended with the coming of NRN, apart from in tunnels where the NRN will not work. The NRN may be used by the driver to contact the signalman when detained at a signal without a signal post telephone, or where the telephone is not located in a position of safety. At these signals, a sign will be provided stating the telephone number for the signal box concerned (see [9.43 - 9.46]).
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Drivers are required to manually set the NRN radio to the correct channel for the area that the train is in and to change channels as the train moves from one radio zone to another. As with CSR, signs are provided at places where the channel needs to be changed, and they show the channel code that applies ahead. A later design of radio channel indicator (in use by 1985), had the diamond shape set against a black background [19.4]. This was also used in relation to CSR. Note that only one radio system is allowed inside any driving cab.
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[19.4] Radio Channel Indicator.
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The Radio Electronic Token Block (RETB) signalling system uses a radio network for the transmission of electronic tokens and for verbal communication between train and signalman. The first application was between Dingwall and Kyle of Lochalsh in 1984. Radio channel indicators of the standard design (see [19.4]) were installed on lines with RETB signalling.
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For a period c.1991, two radio systems were in use over the lines controlled from Inverness (RETB) Signalling Centre. Locomotives were fitted with the original band 2 radio equipment. Introduced from 1989, the Class 156 'Sprinters' used band 3 equipment. Two different channel codes thus applied over any given section of line. The signs showing the original band 2 codes were altered to have a yellow background [19.5] in order to distinguish them from the new band 3 signs, which had the usual white background. The band 2 signs were removed in c.1992.
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[19.5] Band 2 Radio Channel Indicator (RETB).
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Where CSR is in use, drivers are required to go through a 'set up' procedure that involves entering a four-digit radio identification number into the system. In most cases, the number shown on the signal identification plate (see Section 9) is used for this purpose, leading zeros being added as necessary to make up the four digits. At some locations, however, a distinct radio identification number needs to be used (because two or more signals in the vicinity may share the same number, albeit with different prefix letters). Where such circumstances apply, the radio identification number is shown on a separate plate termed an 'alias' plate. The alias plate, introduced in 1992, has white figures on a blue background [19.6]. An alias plate may also be provided at a location where no signal exists.
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[19.6] Alias Plate.
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The new design of radio channel indicators introduced from 1996 bear the initials of the radio system to which they apply [19.7 - 19.9].
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[19.7] Radio Channel Indicator for CSR.
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[19.8] Radio Channel Indicator for NRN.
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[19.9] Radio Channel Indicator for RETB.
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No sign is usually provided at the point where radio coverage ends, but there are examples of CSR termination boards [19.10] (e.g. Grain Branch, and Fawkham Junction).
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[19.10] CSR Termination Board.
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In North Kent, a non-standard form of alias plate with a white background and the letters "CSR" [19.11] was used instead of the standard type with a blue background (see [19.6]).
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[19.11] Non-standard Alias Plate.
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The "Global System for Mobile communications-Railway" (GSM-R) is a digital system that will replace the outdated analogue systems used by CSR and NRN. In connection with GSM-R trials, in November 2001 signs were installed at Oxford and Didcot stations, where the CSR/GSM-R changeover takes place. These signs only apply to Class 165/166 trains. At Oxford, signs advise drivers of northbound Cotswold Line services to switch on GSM [19.12], or CSR in the case of southbound services [19.13]. Signs were installed at the west end of Didcot station (Platforms 3 and 4), where services change direction [19.14].
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[19.12] "Switch On GSM" Sign (Oxford).
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[19.13] "Switch On CSR" Sign (Oxford).
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[19.14] "Changeover CSR / GSM" Sign (Didcot).
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From 2002, drivers over certain routes were issued with a GSM-R (IVRS) hand portable (IVRS = Interim Voice Radio System). The GSM-R (IVRS) hand portable must be used, in designated areas, to contact the signalman in an emergency where protection of the line is required. This was a safety requirement in areas where axle counters replaced track circuits as the means of train detection, e.g. Stoke-on-Trent (2002) and Ledburn Junction (2003). Signs are installed to mark the entrance to [19.15] and exit from [19.16] a GSM-R radio network area. With the GSM-R system, there are no channel codes.
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[19.15] GSM-R Entry Board.
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[19.16] GSM-R Exit Board.
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The GSM-P system, which facilitates emergency contact between Operations Control and drivers, is in use on the lines from Birmingham (Small Heath South Junction) to Hartlebury, Stratford-upon-Avon and Banbury. Signs are installed to remind drivers to switch on the GSM-P [19.17].
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[19.17] "Switch On GSM" Sign.
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Trials of a fully functional GSM-R system commenced on the Glasgow North Electric lines in October 2007. A distinct alias plate for GSM-R [19.18] is required because it may be co-located with an ordinary alias plate provided for the CSR system (see [19.6]). A GSM-R alias plate has just three digits, and these do not match the last three digits of the four-digit number used for CSR set-up purposes.
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[19.18] GSM-R Alias Plate.
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