Northern Ireland

In August 2024, the control of some lines in central Belfast was transferred from Belfast Central signal box to the Grand Central workstation at the new Northern Ireland Rail Operating Centre (NIROC). The existing signal prefix code "CL" was retained inside the area migrated to the Grand Central workstation as well as in the adjacent area that remains under the control of Belfast Central signal box. Because the same prefix code is used in both areas, a plate bearing the letters "GC" [NI.1] was attached to each signal with a telephone connected to the Grand Central workstation, to remind drivers who they are speaking to.

In 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.18] and [IE.23 - IE.27]). However, permanent speed restriction signs applicable to diverging routes are fitted with a standard matching design of directional arrow positioned below the board [NI.4].

In common with current practice in Great Britain, a warning indicator may be installed on the approach to a severe reduction in permissible speed [NI.5].

Some early whistle signs remain, which comprise a cut-out letter "W" [NI.6]. The more recent whistle boards are of the same circular pattern that is standard in Great Britain (see [15.7]).

'Distant monitored' level crossings were unique to Northern Ireland, but none now remain. Those without barriers were designated as "Automatic Open Crossing, Distant Monitored" (AOCD), and those equipped with half barriers were termed "Automatic Half Barrier Crossing, Distant Monitored" (AHBD). Both appeared alike from a train driver's perspective, and in some respects they were similar to an "Automatic Open Crossing, Locally Monitored" (AOCL). The driver's white light (see [16.15]) was, however, located some distance on approach to the crossing and in some instances was co-located with the crossing speed restriction sign (see [16.28]). Its position was too far for an approaching train driver to observe whether the crossing was clear of obstructions. The crossing was therefore 'distant monitored' from a signal box, where the signalman had the facility to extinguish the driver's white light in an emergency. Higher crossing speeds for trains were permitted at AOCDs in comparison to AOCLs. The advance warning board for a distant monitored crossing had a black St. Andrew's cross on a white background [NI.7] instead of the usual St. George's cross (see [16.17]).

Marker boards may be installed on either side of a user-worked level crossing to help engineering staff to check that sighting distances for crossing users have not been compromised by vegetation growth. These comprise an upright rectangular board divided diagonally into black and white sections [NI.8].