Absolute Block. Uncontrolled When Printed Document to be part superseded by GKRT0055 Iss 1 and GKRT0077 Iss 1 (published on 07/09/2013)

Transcription

1 Signatures removed from electronic version Submitted by... Richard Genner Nominated Responsible Manager Approved by... Philip Wiltshire Chairman, Train Control & Communications Subject Committee Approved by... Michael Harwood Chairman, Operations Standards Subject Committee Authorised by R Illingworth... for Dr. M Walter Controller, Safety Standards Synopsis: This standard sets out the signalling requirements to ensure the safe movement of trains where the system is employed. This document is the property of Railtrack PLC. It shall not be reproduced in whole or in part without the written permission of the Controller, Safety Standards, Railtrack PLC. Published by Safety & Standards Directorate Railtrack PLC Floor 2, Fitzroy House 355 Euston Road London NW1 3AG Copyright 1997 Railtrack PLC

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3 Page 1 of 13 Contents Description Page Part A Part B References Issue record 2 Responsibilities 2 Compliance 2 Health and Safety Responsibilities 2 Supply 2 1 Purpose 3 2 Scope 3 3 Definitions 3 4 Application 4 5 Principles of Operation 4 6 System Requirements 5 7 Permissive and Shunt Working 8 8 Switching Out of Signal boxes 8 9 Ground Frames 9 10 Level Crossings System Failures R A I L T R A C K 1

4 Page 2 of 13 Part A Issue record Responsibilities Compliance Health and Safety Responsibilities Supply This standard will be updated when necessary by distribution of a complete replacement. Amended or additional parts of revised pages will be marked by a vertical black line in the adjacent margin. Issue Date Comments 1 July 97 New standard. Supersedes SSP 9, SSP 16, SSP 24, SSP 56 and SSP 77 which are cancelled. Supersedes SSP 80 section 4.4. s are mandatory on all members of the Railway Group* and apply to all relevant activities which fall within the scope of each individual s Railway Safety Case. If any of those activities are performed by a contractor, the contractor s obligation in respect of s is determined by the terms of the contract between the respective parties. Where the contractor is himself a duty holder of a Railway Safety Case then s apply directly to the activities described in his Railway Safety Case. *The Railway Group comprises Railtrack and the duty holders of Railway Safety Cases accepted by Railtrack. The provisions of this are mandatory for design and implementation work undertaken on schemes for which the Signalling Scheme Plan is approved on or after 6th December Railtrack shall consider the need to meet the requirements of this standard when a Signalling Scheme Plan approved prior to 6th December 1997 is altered on or after 6th December Retrospective action is not generally required in respect of existing layouts. Railtrack shall however consider the need to meet the requirements of this standard if there is, on or after the 6th December 1997, a material change to the usage of an Absolute Block Signalling installation (e.g. a significant change to the train service pattern) or other material change to circumstances, which in themselves do not require any change to the signalling installation. In authorising this standard, Railtrack PLC makes no warranties, express or implied, that compliance with all or any of s is sufficient on its own to ensure safe systems of work or operation. Each user is reminded of its own responsibilities to ensure health and safety at work and its individual duties under health and safety legislation. Controlled and uncontrolled copies of this standard must be obtained from the Catalogue Secretary, Railtrack Safety & Standards Directorate, Floor 2, Fitzroy House, 355 Euston Road, London NW1 3AG. Telephone: Facsimile: or (BT) or (BT) 2 R A I L T R A C K

5 Page 3 of 13 Part B 1 Purpose 2 Scope 3 Definitions To define the signalling requirements to ensure the safe movement of trains on running lines where signallers are required to ensure that the train has cleared the block section and is complete. The contents of this standard apply to all lines where the trains are signalled in accordance with the Regulations for Train Signalling by the System. ( Regulations). In addition to unidirectional lines, the application may include single or bi-directional lines utilising interlocked block section controls. Block Signal - A stop signal that controls the entrance to or signifies the termination of a block (or signal) section and any other stop signals within station limits. The following types are specifically identified within this standard: Home Signal - The first stop signal controlled by a signal box and the signal that controls the exit from an absolute block section. Section Signal - A stop signal controlling the entrance to an absolute block section or an intermediate block section. Intermediate Block Home Signal - A stop signal controlling the exit from an intermediate block section. Although an intermediate block home signal controls the entrance to an absolute block section it is referred to as the intermediate block home signal. Block Sections etc. - Section - The line between the last stop signal (i.e. section signal or intermediate block home signal) controlled from one signal box and the first stop signal (i.e. home signal) controlled from the next signal box in the same direction of travel. Station Limits - The line between the home signal and the section signal worked from the same signal box and in the same direction of travel Intermediate Block Section - The line between the section signal and the intermediate block home signal worked from the same signal box and in the same direction of travel. Clearing Point - A point beyond a home signal up to which the line must be set and clear before a signalled running move may approach the home signal. Non-block Signal - A mid-section stop signal specifically provided for the protection of a level crossing, or other hazard, and without block or signal section controls. R A I L T R A C K 3

6 Page 4 of 13 Track Circuit - A portion of railway line having fixed boundaries and providing information on its state of occupancy to the signalling system. Within this standard, this traditional name does not preclude alternative forms of train detection. 4 Application Absolute block signalling may be employed on any line (generally unidirectional) where the level of traffic does not necessitate train detection throughout the length of the line. The integrity level, as determined by this standard, shall be sufficient for the application. Absolute block signalling is not appropriate for: extensive station limits (track circuit block shall be used); or consecutive intermediate block sections (track circuit block to the next signal box shall be used). It is necessary to observe that arriving trains are complete. Where practicable, signal boxes shall be positioned to facilitate direct observation of arriving trains and the position shall also provide the best possible view of signals and station limits. These views shall not be unduly restricted by the passage of trains or by other temporary obstructions. Where it is not practicable for signallers to directly observe arriving trains, alternative means shall be provided to verify that trains are complete. At home signals, section signals and intermediate block home signals, the following facilities are not permitted: train operated route release; automatic route setting; automatic working. The following facilities, amongst others, may be used in conjunction with absolute block: intermediate block sections; permissive and shunt working; mechanically operated signals; automatic working of distant signals and/or aspects, fixed distants and (reflectorised) distant boards. 5 Principles of Operation Signals shall be provided for all normal train movements. Where trains are required to reverse a signal shall be provided at the point of reversal to control the movement in the reverse direction. Except where permissive or shunt working is allowed, the block system shall only permit one train in a block section at any time. Block and signal controls shall support operation in accordance with the Regulations and Signalling General Instructions. Instructions or controls shall not permit an incorrect sequence of events. 4 R A I L T R A C K

7 Page 5 of 13 6 System Requirements The following requirements are divided into three sections of line but there are interactions at the transitions. All relevant requirements shall be satisfied. 6.1 Section Signals - The entrance to absolute block sections shall be protected by a section signal (which may be combined with a home signal, as described in section 6.2) or by an intermediate block home signal. At the exit, there shall be a home signal or equivalent stop board. Train Detection - On the immediate approach to the home signal, there shall be a track circuit which is subsequently referred to as the berth track circuit. Generally, the length of detected line shall not be less than 180 metres (200 yards). Railtrack shall determine the requirement for train detection within the clearing point(s) and this shall be consistent with the requirements of the Regulations. The track circuit(s) shall be indicated at the signal box controlling the home signal. Block section controls - A three state control and indication system shall be provided for each absolute block section. The signaller at the exit end of the section shall control an indicator in his/her own signal box and a duplicate indicator at the entrance end signal box. The three block indications shall be Line Clear, Normal and Train On Line and the default indication shall be Normal. (On some block instruments the Normal position is labelled Line Blocked or Line Closed).The following additional controls shall be provided at the exit end signal box: Irrespective of the signaller s control, the block indicators shall be automatically placed to and maintained at Train On Line when the berth track circuit is occupied. Any additional control shall not be misleading or restrictive. To ensure that signals are replaced after each train and when a train is cancelled, the following shall be proved before a Line Clear can be effected: distant aspects at caution or preliminary caution; where colour light signals provided, distant aspects lit; home signal lever or control normal; where repeater provided, home signal at danger; where colour light signal provided, home signal lit. Additionally where there is a single or bi-directional line with interlocked block section controls, the following shall be proved: opposing direction protecting signal(s) lever or control normal and aspect at danger, unless protection by points is assured; opposing direction block indication at Normal. An override device with incremental counter shall be provided for failure of the aspect and light proving and instructions shall mandate safe operation of the device. When in use, it shall be R A I L T R A C K 5

8 Page 6 of 13 necessary to operate the override device before each indication of Line Clear. Before a subsequent Line Clear can be indicated, there shall be the following additional proving if a train passes through the section: the berth track circuit described above occupied and clear and, where practicable, protection against a single momentary failure; or there shall be the following additional proving if a train is cancelled: co-operative operation of cancelling devices in both signal boxes with the entrance end signal lever or control proved normal (preferred arrangement); or operation of a time-delayed cancelling device at the exit end signal box (alternative arrangement with approximately 2 minutes delay). Cancellation shall automatically place the block indicators at Train On Line before reverting to normal working. Audible indication - Where the entrance to an absolute block section is at an intermediate block home signal or at a section signal that is remote from the signal box, Railtrack shall consider the provision of an audible indication at the entrance end signal box to signify that a train is entering the absolute block section. The indication shall differentiate between signal off or signal on (e.g. short ring, continuous alarm until acknowledged). Signal controls - Except for shunt or permissive working when the section is occupied, signal controls shall require the block indication to be at Line Clear before an entrance signal is cleared (i.e. Line Clear release of section signal or, where provided, intermediate block home signal). This release shall be cancelled when a train is detected as entering the section (preferred) or alternatively when an entrance signal is cleared. The cancellation shall remain effective until the block control is at Train On Line. Distant aspects may work automatically, provided the controlling signal box has a replacement facility which will place and maintain the aspects at caution or preliminary caution. Regulations require the signaller to maintain these distant aspects at caution or preliminary caution when there is a failure of the block indicators. Note - The home signal generally protects station limits and it will require controls in accordance with sub-section 6.2. In the absence of station limits the home signal may act as a section signal and it shall be controlled in accordance with this sub-section, sub-section 6.3 or other relevant block standard as appropriate. Communication between signal boxes - A means of exchanging coded bell signals, supplemented by voice communication, shall be provided between the two signal boxes. It shall be possible for each 6 R A I L T R A C K

9 Page 7 of 13 signaller to readily associate a bell signal with a particular line or signal box. 6.2 Station Limits The following requirements supplement the interlocking principles in s GK/RT0039 and GK/RT0060. Signals - Station limits shall be protected by a home signal and at the exit, there shall be a section signal. In the absence of station limits, one signal will act as home and section signal and the dominant designation shall be home signal. Train detection - A track circuit(s) shall be provided for any portion of line that is not clearly visible from the signal box. Where a track circuit(s) is provided for this purpose, it shall extend to the block signal ahead. The preferred arrangement is train detection throughout station limits, with track circuits to suit comprehensive signal controls. Non-preferred arrangements shall be specifically approved by Railtrack and shall take account of fog conditions. The track circuits shall be indicated at the controlling signal box. Signal controls - Except for shunt or permissive working when the section is occupied, block signal controls shall, wherever there is train detection, prove that the line is clear to the next block signal, including any appropriate overlap ahead of the next signal. These controls may, however, be omitted where the signaller could be misled by partial or inconsistent controls and the portion of line is clearly visible from the signal box. The required overlap is specified in GK/RT0078 and is dependant on the type of signal. To ensure that block signals are replaced after each train, signal sticks and automatic replacement of signal aspects shall be provided where practicable. Where a block signal ahead of the home signal does not have a signal stick with prompt, automatic and guaranteed replacement, the replacement shall be proved before the clearance of any block signal in rear. This replacement proving shall be lever or control plus aspect but may be lever only where: a signal is mechanically operated, and an arm repeater is not provided, and the signal does not give entry to a bi-directional line worked by any non- token system (unless protection by points is assured), and the signal(s) in rear cannot work automatically. Note- The section signal shall be controlled in accordance with subsection 6.1, 6.3 or other relevant block standard. 6.3 Intermediate Block Section Signals - Intermediate block sections shall be protected by a section signal(s). At the exit, there shall be an intermediate block home signal. Intermediate block home signals shall generally be worked from the signal box in rear and shall not be used for the protection of points. R A I L T R A C K 7

10 Page 8 of 13 Train detection - There shall be train detection throughout an intermediate block section. An overlap ahead of an intermediate block home signal shall have a separate track circuit. All track circuits shall be indicated at the controlling signal box. Signal controls - Except for shunt or permissive working when the intermediate block section is occupied, section signal controls shall prove that the intermediate block section and overlap is clear. The required overlap is specified in GK/RT0078 and is dependant on the type of signal. To ensure that intermediate block home signals (and any separate distant signals) are replaced after each train, a signal stick and automatic replacement of the signal aspects shall be provided where practicable. Where there is not a signal stick with prompt, automatic and guaranteed replacement, the replacement shall be proved before the clearance of any section signal in rear. This replacement proving shall be lever or control plus aspect but may be lever only where: a signal is mechanically operated, and an arm repeater is not provided. Note - The intermediate block home signal protects an absolute block section and it shall be controlled in accordance with sub-section Stop Signal Communications A signal post telephone or alternative communication facilities shall be provided at an intermediate block home signal. At other signals, Railtrack shall consider the need for signal post telephones or alternative communication facilities, for example where there is an anticipated or known requirement for the signaller to instruct drivers without undue hazard or delay (e.g. at signals protecting level crossings and at signals controlling the entrance to a section where there are level crossings). 6.5 Signal Identification Signal Identification Plates (including combined Sign and Identification Plates) shall be provided in accordance with GK/RT Permissive and Shunt Working 8 Switching Out of Signal boxes Where authorised by Railtrack, signalling shall be provided to permit trains to enter an occupied section of line under the authority of a position light signal, semaphore subsidiary signal or a semaphore shunting signal. The interlocking and controls shall be in accordance with Railway Group Standard GK/RT0060. If a signal box controlling absolute block sections is switched out and the lines remain open for traffic, the adjacent absolute block sections and any interposed station limits or intermediate block sections shall form a single absolute block section. The switching out device block switch shall create a through connection for the relevant block controls and all 8 R A I L T R A C K

11 Page 9 of 13 relevant communications. The switching out device shall, generally, nullify any signal aspect controls that relate to train detection at the switched out signal box. Point detection shall continue to be in accordance with the relevant chart in section 5 of GK/RT0039. The appropriate block and signal controls shall not be circumvented by transient conditions due to operation of the switching out device. 9 Ground Frames The following requirements supplement section 4 of Railway Group Standard GK/RT Section Signals - The section signal(s) shall protect the ground frame when it is released. Protection by an intermediate block home signal is not permitted. Railtrack shall consider the need for appropriate protection on sidings and other lines. When released the ground frame may work additional signals which may or may not be slotted by the signal box. To avoid inhibition of a proceed aspect at the section signal(s), a separate non-block signal may be provided in order to satisfy the requirements of the relevant detection chart in section 5 of GK/RT0039. A remote ground frame marker may be used in lieu of a nonblock signal and if a marker is provided the relevant detection requirements shall apply to the associated distant signal. Additional train detection - Where there is a shutting-in facility, train detection shall be provided. The train detection shall commence: where reasonably practicable, at the protecting section signal; or otherwise, where the length of train detection is reduced, at maximum train length plus 100 metres (110 yards) on the approach side of the ground frame points or associated clearance point. In such cases, where there is a residual risk that part of a train may be left undetected on the running line, the residual risk shall be controlled by suitable entries in the Signal Box Instructions. The train detection shall, as a minimum, terminate: at the clearance point of ground frame facing points; or 200 metres (220 yards) beyond the toe of ground frame trailing points. This train detection shall be indicated at the signal box controlling the ground frame release. Release - Ground frames shall be released from the signal box at the entrance to the section. The following requirements shall be satisfied before the signaller releases a ground frame: the protecting section signal(s) on and, where provided, free of approach locking; and the portion of line between the ground frame and any signalling feature ahead of the ground frame that is controlled by the same signal box, route locked and detected. This requirement and any associated train detection may be omitted where there is an additional signal(s) to safely control a departing train, and R A I L T R A C K 9

12 Page 10 of 13 additionally for ground frames without a shutting-in facility, the block indication at Train On Line; for ground frames with a shutting-in facility, a train safely at a stand for duties at the ground frame and the block indication at Train On Line; or indication at Line Clear. This Line Clear release shall be cancelled when a train is detected as entering the additional train detection clear of trains and the block the section (preferred) or alternatively when the release is given. The cancellation shall remain effective until the block control is at Train On Line. Normalisation - The following requirements shall be satisfied before the signaller normalises a ground frame release: an assurance from the ground frame operator that it is safe to normalise; and proof from the ground frame that the release lever or control and associated equipment is normal, as specified in Railway Group Standard GK/RT0061. Signal controls - The section signal(s) protecting the absolute block section and the ground frame shall be controlled in accordance with subsection 6.1 of this standard and shall additionally require: at the signal box, the signaller s ground frame release normal; and where there is not a separate non-block signal at the ground frame, the ground frame points detected normal in accordance with the relevant detection chart in section 5 of GK/RT Station Limits Signals - A block signal(s) shall protect the ground frame when it is released. Railtrack shall consider the need for appropriate protection on sidings and other lines. When released the ground frame may work additional signals which may or may not be slotted by the signal box Release - Ground frames shall be released from the signal box. The following requirements shall be satisfied before the signaller releases a ground frame: controls equivalent to those that would have been applied if it had been possible to directly operate the points from the signal box; and the portion of line between the ground frame, the block signal ahead and any required overlap, route locked and detected. This requirement and any associated train detection may be omitted where there is an additional signal(s) to safely control a departing train. Normalisation - The following requirements shall be satisfied before the signaller normalises a ground frame release: 10 R A I L T R A C K

13 Page 11 of 13 an assurance from the ground frame operator that it is safe to normalise; and proof from the ground frame that the release lever or control and associated equipment is normal, as specified in Railway Group Standard GK/RT0061. Signal controls - The block signal(s) protecting the ground frame shall be controlled in accordance with sub-section 6.2 of this standard and shall additionally require: at the signal box, the signaller s ground frame release normal; at the ground frame, points detected normal in accordance with the relevant detection chart in section 5 of GK/RT Intermediate Block Section Signals - The section signal(s) shall protect the ground frame when it is released. Railtrack shall consider the need for appropriate protection on sidings and other lines. When released the ground frame may work additional signals which may or may not be slotted by the signal box. To avoid inhibition of a proceed aspect at the section signal(s), a separate non-block signal may be provided in order to satisfy the requirements of the relevant detection chart in section 5 of GK/RT0039. A remote ground frame marker may be used in lieu of a nonblock signal and if a marker is provided the relevant detection requirements shall apply to the associated distant signal. Release - Ground frames shall be released from the signal box. The following requirements shall be satisfied before the signaller releases a ground frame: the protecting section signal(s) on and, where provided, free of approach locking; and the intermediate block section and any required overlap clear of trains; or occupied by a train safely at a stand for duties at the ground frame; and the portion of line between the ground frame, the intermediate block home signal and any required overlap, route locked and detected. This requirement and any associated train detection may be omitted where there is an additional signal(s) to safely control a departing train. Normalisation - The following requirements shall be satisfied before the signaller normalises a ground frame release: an assurance from the ground frame operator that it is safe to normalise; and proof from the ground frame that the release lever or control and associated equipment is normal, as specified in Railway Group Standard GK/RT0061. R A I L T R A C K 11

14 Page 12 of 13 Signal controls - The section signal(s) protecting the ground frame shall be controlled in accordance with sub-section 6.3 of this standard and shall additionally require: at the signal box, the signaller s ground frame release normal (i.e. restored); and where there is not a separate non-block signal at the ground frame, the ground frame points detected normal in accordance with the relevant detection chart in section 5 of GK/RT Level Crossings The following requirements supplement the gate box and level crossing requirements in s GK/RT0061 and GK/RT0070 Signals - Where running line signals are required for the protection of a level crossing these may be block or non-block signals. Where a block signal protects a manned level crossing the designation intermediate block home signal is not permitted. On other than running lines Railtrack shall consider the need for appropriate protection. Signal controls - Block signals, where provided, shall additionally be controlled in accordance with section 6 of this standard. 11 System Failures The system shall be so designed that no credible failure shall result in the clearance of a signal or where practicable the maintenance of a clear aspect when the conditions are not safe to do so. Railtrack shall ensure that suitable operating procedures are available to ensure safe working of trains during all credible failure modes. Where the train detection does not generate continuous information about the state of the railway, the operating procedures shall include resetting and restoration to service in accordance with GK/RT R A I L T R A C K

15 Page 13 of 13 References BR BR 30062/2 GK/RT0009 GK/RT0027 GK/RT 0039 GK/RT0060 GK/RT 0061 GK/RT0070 GK/RT0078 Signalling General Instructions Regulations for Train Signalling by the System Identification of Signalling and Related Equipment Resetting and Restoration to Service of Signalling Equipment and Systems Semaphore and Mechanical Signalling Interlocking Principles Shunters Releases, Ground Frames, Switch Panels and Gate Boxes Signalling Requirements for Level Crossings Overrun Protection and Mitigation R A I L T R A C K 13