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Northern Ireland
Northern Ireland
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Although Northern Ireland remains part of the United Kingdom, its railways are run entirely separately from those in Great Britain. After the partitioning of Ireland in 1921, the British railway inspectorate ceased to operate in either part of the island. Northern Ireland Railways have chosen to continue following the practices of Great Britain, but they are not obliged to do so. Signalling and signage in Northern Ireland can therefore generally be considered as a subset of that in Great Britain.
Mechanical signalling is on the verge of extinction in Northern Ireland. Upper quadrant semaphore signals had once existed at Larne Harbour and on the Bangor line, but the few surviving semaphore signals in Northern Ireland are all of the 'somersault' type (see [2.36]).
Older permanent speed restriction signs were of the 'cut-out' type, additionally surmounted by a cut-out letter "C" for 'commencement' [NI.1]. The terminating point of the speed restriction was correspondingly marked by a cut-out letter "T" [NI.2].
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[NI.1] Permanent Speed Restriction Sign.
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[NI.2] End of Permanent Speed Restriction Marker.
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In what is a significant departure from the usual British practice, modern speed restriction signs in Northern Ireland, both permanent and temporary, are of the same types as those found in the Republic of Ireland (see [IE.17] and [IE.19 - IE.23]). Additionally, permanent speed restriction signs applicable to diverging routes are fitted with a standard matching design of directional arrow positioned below the board [NI.3].
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[NI.3] Permanent Speed Restriction Sign with Directional Arrow (e.g. applicable to right-hand divergence).
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Some early whistle signs remain which comprise a cut-out letter "W" [NI.4]. The more recent whistle boards are of the same standard type used in Great Britain (see [15.6]).
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[NI.4] Whistle Sign.
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'Distant monitored' level crossings are unique to Northern Ireland. These were either open or had half-barriers, being termed "Automatic Open Crossing, Distant Monitored" (AOCD) and "Automatic Half Barrier Crossing, Distant Monitored" (AHBD) respectively. Both appear alike from the point of view of the train driver, and in some respects similar to an "Automatic Open Crossing, Locally Monitored" (AOCL). The driver's white light (see [16.5]) is however located some distance before reaching the crossing and in some cases is co-located with the crossing speed restriction sign (see [16.14]). This is too far away for the driver to be able to ascertain whether the crossing is clear of obstructions. The crossing is therefore 'distant monitored' from a signal box, where the signalman has the facility to extinguish the driver's white light in an emergency. Higher crossing speeds were permitted at AOCDs than is the case at AOCLs. The advance warning board for a distant monitored crossing has a black St. Andrew's cross on a white background [NI.5] instead of the usual St. George's cross (see [16.7]). No AOCD (or AOCL) level crossings remain in Northern Ireland, but there are three AHBDs at Cullybackey.
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[NI.5] Advance Warning Board for AOCD/AHBD.
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Radio channel indicators are similar to the type that is currently standard in Great Britain (see [19.7 - 19.9]), but are somewhat wider and have the letters "RAD CH" (for 'Radio Channel') at the top [NI.6].
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[NI.6] Radio Channel Indicator.
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Signs may be provided by Permanent Way Department staff to denote the presence of heavy vegetation at the lineside [NI.7].
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[NI.7] Heavy Vegetation Sign.
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