Lineside Signals, Indicators and Layout of Signals Iss 4.pdf · Page 2 of 40 RSSB Railway Group Standard GK/RT0045 Issue Four Date December 2014 Lineside Signals, Indicators and Layout

Railway Group Standard

GK/RT0045

Issue Four

Date December 2014

Lineside Signals, Indicators and Layout of Signals

Synopsis

This document defines the configuration and layout of lineside signalling equipment that is used to convey information to infrastructure managers operating stations, and railway undertaking personnel.

Copyright in the Railway Group Standards is owned by Rail Safety and Standards Board Limited. All rights are hereby reserved. No Railway Group Standard (in whole or in part) may be reproduced, stored in a retrieval system, or transmitted, in any form or means, without the prior written permission of Rail Safety and Standards Board Limited, or as expressly permitted by law.

RSSB Members are granted copyright licence in accordance with the Constitution Agreement relating to Rail Safety and Standards Board Limited.

In circumstances where Rail Safety and Standards Board Limited has granted a particular person or organisation permission to copy extracts from Railway Group Standards, Rail Safety and Standards Board Limited accepts no responsibility for, nor any liability in connection with, the use of such extracts, or any claims arising therefrom. This disclaimer applies to all forms of media in which extracts from Railway Group Standards may be reproduced.

Published by: RSSB Block 2 Angel Square 1 Torrens Street London EC1V 1NY © Copyright 2014 Rail Safety and Standards Board Limited

Uncontrolled When Printed Document comes into force and supersedes GKRT0045 Iss 3 as of 07/03/2015

Superseded in part by GKRT0045 Iss 5 and in part by RIS-0737-CCS Iss 1 with effect from 03/09/2016

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Issue record

Issue Date Comments

One 06 February 2010 Original document

Two 03 March 2012 Replaces issue one

Small scale change amendment to GK/RT0045 issue two necessitated by revision of 2.3.1.2 and 2.3.1.4 to permit the use of a bar of light or a line of five lunar white light points to display the indication of route

Clauses 9.1.1, 9.1.2, 9.1.3, 9.1.4 and 9.1.5 relating to identity of signals and indicators were removed from GK/RT0045 issue two as these were transferred to GK/RT0009 issue four which was published in June 2011

Three 01 December 2012 Replaces issue two

Small scale change amendment to clause 2.3.2.5c) to allow the use of the ‘X’ alphanumeric route indicator to additionally denote a movement along a bi-directional line in the opposite direction to the normal flow of traffic

Four December 2014 Replaces issue three

Revisions associated with the publication of GK/RT0057 issue one and GK/RT0058 issue one

Withdrawal of requirements for passable stop signals that are not designated as intermediate block home signals

Amended or additional parts and/or sections of revised pages have been marked by a vertical black line in the adjacent margin.

Superseded documents

The following Railway Group Standard is superseded, either in whole or in part as indicated:

Superseded documents Sections superseded

Date when sections are superseded

GK/RT0045, issue three, Lineside Signals, Indicators and Layout of Signals

All 07 March 2015

GK/RT0045, issue three, Lineside Signals, Indicators and Layout of Signals, ceases to be in force and is withdrawn as of 07 March 2015.

Supply

The authoritative version of this document is available at www.rgsonline.co.uk. Uncontrolled copies of this document can be obtained from Communications, RSSB, Block 2, Angel Square, 1 Torrens Street, London EC1V 1NY, telephone 020 3142 5400 or e-mail [email protected]. Other Standards and associated documents can also be viewed at www.rgsonline.co.uk.



http://www.rgsonline.co.uk/

mailto:[email protected]


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Contents

Section Description Page

Part 1 Purpose and Introduction 5 1.1 Purpose 5 1.2 Introduction 5 1.3 Approval and authorisation of this document 6

Part 2 Application of Lineside Signalling Equipment 7 2.1 Display of operational information using the signalling system 7 2.2 Lineside signal and indicator configuration requirements 7

Part 3 Layout of Signals: Requirements for Stop Signals 11 3.1 Provision of stop signals and signalling indicators 11

Part 4 Layout of Signals: Aspect Sequences 15 4.1 Requirements for cautionary aspect sequences 15 4.2 Requirements for banner repeating signal aspects 20

Part 5 Layout of Signals: Junction Signalling 21 5.1 Requirements for route indications 21 5.2 Junction signalling: colour light signal aspect sequences 23 5.3 Junction signalling: semaphore signal aspect sequences 28 5.4 Junction signalling: AWS requirements 28 5.5 Junction signalling: prohibited aspects 28

Part 6 Layout of Signals: Bi-directional Signalling 30 6.1 Bi-directional signalling 30

Part 7 Degraded Signalling 31 7.1 Degraded colour light signalling 31

Part 8 Application of this document 32 8.1 Application - infrastructure managers 32 8.2 Application - railway undertakings 33 8.3 Health and safety responsibilities 33

Appendices Appendix A Positioning Criteria for Stop Signals on Electrified Lines 34

Tables Table 1 Methods of junction signalling 23 Table 2 Speed ranges for flashing aspect sequences 24



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Figures

Figure 1 Example of a 4-aspect colour light splitting distant signal (left-hand divergence) mounted on the left-hand side of the line 7

Figure 2 Example of a 3-aspect to 4-aspect transition using transition method 1 17 Figure 3 Example of a 3-aspect to 4-aspect transition using transition method 2 17 Figure 4 Example of a 3-aspect to 4-aspect transition using transition method 3 18

Definitions 37

Abbreviations and acronyms 39

References 40



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Part 1 Purpose and Introduction

1.1 Purpose

1.1.1 The purpose of this document is to specify the application of lineside signalling equipment that is used to convey information to infrastructure managers at stations and railway undertaking personnel. This document mandates the requirements for:

a) Certain configuration requirements for lineside signals and indicators.

b) The criteria for positioning signals within the layout.

c) The permitted type(s) of lineside signal and their application constraints.

d) The permitted sequences of signal aspects and indications displayed to drivers.

1.1.2 This document is applicable to areas where train movements are controlled using lineside signalling.

1.1.3 This document includes some requirements applicable to areas where train movements are controlled using the European Rail Traffic Management System (ERTMS) Level 2 without lineside signals. Where this is the case, the particular applicability to ERTMS is described in the applicable clause(s).

1.2 Introduction

1.2.1 Background

1.2.1.1 The operational meanings of signal aspects and indications are set out in Information Handbook RS/521.

1.2.1.2 The layout of signalling equipment is specified so that, when train movements take place, drivers are given sufficient and appropriate movement authority information.

1.2.2 Related requirements in other documents

1.2.2.1 The following Railway Group Standards contain requirements that are relevant to the scope of this document:

GC/RT5021 Track System Requirements

GE/RT8000 Rule Book

GE/RT8037 Signal Position and Visibility

GE/RT8071 Proceed-on-Sight Authorities

GE/RT8075 AWS and TPWS Interface Requirements

GK/RT0044 Controls for Signalling a Train onto an Occupied Line

GK/RT0057 Lineside Signal and Indicator Product Design and Assessment Requirements [in preparation, will replace some parts of GK/RT0045]

GK/RT0058 Lineside Signal Aspect and Indication Requirements [in preparation, will replace some parts of GK/RT0045]



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GK/RT0075 Lineside Signal Spacing and Speed Signage

GO/RT3215 Requirements for the Weekly Operating Notice, Periodical Operating Notice and Sectional Appendix

1.2.3 Supporting documents

1.2.3.1 The following Railway Group documents support this Railway Group Standard:

GK/GN0645 Guidance on Lineside Signals, Indicators and Layout of Signals

1.3 Approval and authorisation of this document

1.3.1 The content of this document was approved by Control Command and Signalling (CCS) Standards Committee on 16 October 2014.

1.3.2 This document was authorised by RSSB on 24 October 2014.



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Part 2 Application of Lineside Signalling Equipment

2.1 Display of operational information using the signalling system

2.1.1 Signalled movement authorities shall be displayed only using the sequences of signal aspects and indications set out in this document.

2.1.2 Signals and indicators shall be readable when viewed from the driving cab.

2.2 Lineside signal and indicator configuration requirements

2.2.1 Colour light signals

2.2.1.1 Except where signal sighting can be consistently achieved without a backboard (for example, where a signal is positioned in a dark environment), a backboard shall be provided with each colour light signal.

2.2.1.2 Where a separate backboard is provided behind the signal head, it shall be of sufficient size to appear no smaller than a signal head mounted backboard.

2.2.2 Splitting distant signals

2.2.2.1 The primary head and offset head shall:

a) Be mounted so that the horizontal separation between signal light centres in the two colour light signal heads is 600 mm – 900 mm, and

b) Be positioned and aligned so that horizontally displayed signal lights appear level to the train driver (see example in Figure 1).

2.2.2.2 The splitting distant signal shall be positioned so that the primary head is located as near as practicable to the driver’s line of sight, that is to say:

a) For signals mounted on the left-hand side of the line, the primary head shall be mounted to the right-hand side of the offset head (see example in Figure 1), and

b) For signals mounted on the right-hand side of the line, the primary head shall be mounted to the left-hand side of the offset head.

Y Y

Y

Primary Head

Offset Head

600 – 900

In 4-aspect areas, the top

yellow light in the offset head

should appear horizontally

aligned with the bottom yellow

light in the primary head

All dimensions in millimetres

Figure 1 Example of a 4-aspect colour light splitting distant signal (left-hand divergence) mounted on the left-hand side of the line



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2.2.3 Co-acting signals (colour light signal and semaphore signal)

2.2.3.1 Co-acting signals shall incorporate:

a) Primary signal and, where relevant, route indicator equipment that is positioned to provide the required long-distance signal sighting and readability, as set out in GE/RT8037, and

b) Co-acting signal and route indicator equipment that displays the same form (that is to say, colour light or semaphore) of signal aspect and route indication as the primary equipment, and positioned to provide the required close-up signal sighting and readability, as set out in GE/RT8037.

2.2.3.2 The primary and co-acting signal and route indicator equipment shall meet the same performance requirements, except where there is insufficient space to provide compatible equipment, in which case:

a) The primary signal and route indicator equipment shall meet the appropriate performance requirement compatible with the long-distance signal sighting and readability, and

b) The co-acting signal head and route indicator equipment shall meet the performance requirement that is appropriate for close-up signal sighting and readability.

2.2.3.3 The same main signal aspect and route indication shall be displayed by the primary and co-acting signals at all times.

2.2.3.4 The same subsidiary / shunting aspect and route indication shall be displayed by the primary and co-acting signals at all times, except at signals where subsidiary / shunting aspects and route indications are omitted from the primary signal.

2.2.3.5 Subsidiary / shunting signal aspects and route indications shall only be omitted from the primary signal if the co-acting signal equipment, on its own, provides the required sighting and readability for these aspects.

2.2.3.6 Colour light signal lights that are designed to flash shall flash in synchronism throughout the primary and co-acting signal heads when flashing aspects are displayed by co-acting signals.

2.2.3.7 Signals shall only display movement authorities towards co-acting signals when both the primary and co-acting signals are detected to be displaying the correct signal aspect, except when a failure of the second yellow light of a double yellow aspect in either the primary signal or co-acting signal results in one signal displaying a more restrictive single yellow aspect in error.

2.2.4 Position light signals

2.2.4.1 Independent position light signals that display the ON aspect using two yellow lights shall only be provided by exception and only as a direct replacement for an existing semaphore yellow shunting disc signal or existing yellow/white position light signal.



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2.2.4.2 Where independent position light signals are to be added to an existing signalling layout that includes independent position light signals that display a different form of ON aspect, the signalling layout shall be designed so that:

a) Drivers will not observe the different forms of ON aspect at the same time during train movements, and

b) The transition between the different forms of ON aspect is clearly defined.

2.2.5 Position light junction indicator

2.2.5.1 Position light junction indicators shall be positioned either above or to one side of the associated colour light signal head to provide the required signal sighting and readability of the combined signal aspects and route indications.

2.2.5.2 The separation distance between an illuminated signal light and the nearest lunar white light or bar of light point shall be 550 mm (minimum) and 1230 mm (maximum).

2.2.6 Train dispatch system indications

2.2.6.1 A self-restoring, secure control device shall be provided for train dispatchers to operate each ‘CD’ and ‘RA’ indication.

2.2.6.2 The ‘CD’ indication shall be displayed only when the control device has been operated.

2.2.6.3 Where the movement authority is displayed by a lineside signalling system:

a) The ‘OFF’ indication shall be displayed only when the associated signal is displaying a proceed aspect.

b) The ‘RA’ indication shall be displayed only when:

i) The associated signal is displaying a proceed aspect, and

ii) The associated control device has been operated.

2.2.6.4 In ERTMS areas:

a) The ‘OFF’ indication shall be displayed only when a train has confirmed that it has received an in-cab movement authority to pass the node to which the OFF indicator applies.

b) The ‘RA’ indication shall be displayed only when:

i) The train has confirmed that it has received an in-cab movement authority to pass the node to which the right away indicator applies, and

ii) The associated control device has been operated.

2.2.7 BU indicators

2.2.7.1 Where provided, BU indicators shall be positioned at a distance beyond the level crossing, so that the ‘BU’ indication is displayed before the front of the train that has passed over the level crossing passes the BU indicator.

2.2.8 Train Protection and Warning System (TPWS) indicators

2.2.8.1 Where a TPWS indicator is required at a stop board, it shall be positioned either:

a) Underneath the relevant stop board so that it is readable from the driving cab, or



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b) Remotely from the stop board; only where drivers are required to leave the driving cab to operate signalling equipment (for example, associated with driver operated token exchange equipment).

2.2.8.2 Where a TPWS indicator at a stop board is combined with a points indicator (for example, at the exit of a passing loop on a single line operated using the no-signaller token remote block system), the points indicator shall be positioned next to the TPWS indicator, so that the points indication is closest to the driver’s line of sight.

2.2.8.3 Where a TPWS indicator at a stop board is associated with a points indicator and a driver’s level crossing indicator:

a) The points indicator shall be positioned next to the TPWS indicator, so that the points indication is closest to the driver’s line of sight, and

b) The driver’s level crossing indicator shall be positioned adjacent to the stop board separately from the points / TPWS indication so that concurrently displayed indications are both readable as separate indications.

2.2.8.4 Where a TPWS indication is associated with a points indicator and / or a level crossing indicator, the indications shall be consistently displayed in a logical sequence at each location along a line of route.

2.2.9 Stop boards

2.2.9.1 The wording displayed on each stop board shall be determined using the process for assessment of compatibility set out in GE/RT8270.

2.2.10 Buffer stop lights

2.2.10.1 Buffer stop lights, where provided, shall comply with all of the following:

a) Display signal red lights, except in sidings at locations where provision of red buffer stop lights would mislead drivers or affect the readability of signals on adjacent lines. In this case the buffer stop lights shall display white lights.

b) Be vertically aligned above the centre line of the track.

c) Be configured so that the lower light is positioned 2400 mm (+/-100 mm) above rail level, and the higher light is positioned to provide a separation distance of 150 mm (+/-10 mm) between the nearest edges of the two lights.

d) Be positioned at the buffer stop, in the same vertical plane as the buffer stop, except where the buffer stop is associated with a sand drag, in which case the lights shall be positioned at the entry end of the sand drag.



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Part 3 Layout of Signals: Requirements for Stop Signals

3.1 Provision of stop signals and signalling indicators

3.1.1 Position of stop signals

3.1.1.1 The signalling layout shall provide for all normal train movements.

3.1.1.2 Except for lines where movement authority information is conveyed using lineside operational signs (see GK/RT0055), the signalling layout shall provide stop signals at the following locations:

a) At the entrance and exit of every block section.

b) At the entrance to every signal section, including signal sections associated with station limits.

c) At the end or exit of every signal section, including signal sections associated with station limits.

d) Where signalling facilities are provided for trains to reverse direction, at the point of reversal.

e) On the approach to a ground frame (see GK/RT0077).

f) On the approach to moveable infrastructure, except where a points indicator is provided instead of a signal.

g) On the approach to level crossings (see GK/RT0192).

h) On the approach to areas protected by a signalling lockout system that is provided for use by railway undertaking personnel, and at the exit from such an area that is used by personnel working on the outside of trains (see GK/RT0212).

i) Where there is a requirement to stop trains to protect against other identified hazards (for example, airport runways).

3.1.1.3 The requirements for positioning stop signals on electrified lines are set out in Appendix B.

3.1.1.4 Stop signals controlling movements through diverging junctions shall be positioned not more than 800 m from the first set of facing points, except where either:

a) The facing points are operated from a ground frame.

b) The stop signal is positioned parallel with other stop signals, one of which is positioned within 800 m of a set of facing points and there are other factors that prevent the positioning of stop signals closer to the junction.

c) The facing points are always set in the same position for facing moves from the stop signal.

d) The facing points are secured out of use (see GC/RT5021).

e) A distance temporarily greater than 800 m is associated with planned engineering stage-works, and details of the excess distance are published in accordance with GO/RT3215.



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3.1.2 Stop signal types, displayed signal aspects and movement authorities

3.1.2.1 Stop signals on running lines shall be main stop signals, except where the criteria for position light signals, semaphore shunting signals and points indicators allow these to be provided as an alternative.

3.1.2.2 Main stop signals shall only be provided using the following equipment types:

a) Colour light signal.

b) Semaphore main stop signal.

c) Stop board.

d) Buffer stop that is indicated to the driver.

3.1.2.3 Independent position light signals and semaphore shunting signals shall only be provided to display shunting movement authorities in either one of the following circumstances:

a) From running lines into sidings.

b) Wholly within sidings.

c) From sidings onto running lines, except at locations where a colour light signal or semaphore stop signal is necessary to mitigate SPAD risk or collision risk.

d) Along running lines, except at locations where a main stop signal is necessary to mitigate SPAD risk or collision risk.

3.1.2.4 Before providing a position light signal or semaphore shunting signal to display shunting movement authorities onto or along running lines, the infrastructure manager and relevant railway undertaking(s) shall jointly assess the SPAD risk and collision risk associated with the planned train movements. Factors to be considered shall include (as appropriate):

a) Visibility and sighting of the stop signal that defines the end of each shunting movement authority on the running line.

b) The distance to the stop signal that defines the end of each shunting movement authority on the running line.

c) The number and frequency of shunting movements from the signal that involves train movements onto running lines.

d) The proportion of shunting movements from the signal that involve train movements onto the running line.

e) The number and proportion of shunting movements from the signal into an occupied section on a passenger line.

3.1.2.5 Where an independent position light signal is provided within a main signal route in a facing direction, the following apply:

a) The position light signal OFF aspect comprising two lunar white lights shall be displayed when the route is set from the main stop signal, and



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b) The position light signal ON aspect shall only be displayed to a driver using a movement authority from the main stop signal if the signaller intentionally replaces the signal to danger in an emergency.

3.1.2.6 Where a semaphore shunting signal is provided within a main signal route in a facing direction:

a) The OFF aspect shall be displayed when the route is set from the main stop signal, and

b) The ON aspect shall only be displayed to a driver using a movement authority from the main stop signal if the signaller intentionally replaces the signal to danger in an emergency.

3.1.2.7 Stepping up or down to a calling-on class route is prohibited.

3.1.2.8 Stepping up or down to a shunt class route is prohibited.

3.1.2.9 Stepping up or down to a PoSA class route is prohibited.

3.1.3 Designation of a stop signal as an ‘intermediate block home’ signal

3.1.3.1 A colour light stop signal or semaphore main stop signal shall only be designated an ‘intermediate block home’ signal if:

a) The signal is located at the end of an additional block section that is controlled by one signal box and operated in accordance with the absolute block regulations, and

b) The next signal section(s) does not incorporate any of the following:

i) Ground frame.

ii) Crossover, facing or trailing points.

iii) Moveable infrastructure (for example, a swing bridge).

iv) Manually controlled level crossing.

v) Automatic level crossing remotely monitored by the signaller.

vi) A directly opposing route or overlap that conflicts with the route or overlap.

vii) Any other hazard protected by the stop signal that, if passed at danger, could result in a collision or derailment.

3.1.4 Provision of point indicators

3.1.4.1 A points indicator shall be provided:

a) On the approach to facing points unless a stop signal is used to display movement authorities through those points, and

b) On the approach to trailing points, unless either:

i) A stop signal is used to display movement authorities through those points, or

ii) A train operated point mechanism is fitted to the trailing points.



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3.1.4.2 A points indicator that displays only a yellow light or a steady red light / yellow light shall only be provided on lines where it is necessary to display consistent indications along a line of route already fitted with this form of indication.

3.1.5 Provision of loading / unloading indicators

3.1.5.1 Loading / unloading indicators shall be provided at locations where the infrastructure manager co-operates with railway undertaking shunting operations by displaying train movement indications in lieu of hand-signalling operations.

3.1.5.2 Where loading / unloading indicators are grouped as a set along a line, all of the indicators in the set shall display the same indication at the same time.

3.1.5.3 A stop signal shall protect the running lines beyond the sidings in accordance with 3.1.1.

3.1.5.4 No indication shall be displayed for movements into a signalled area when the signal applicable to the movement is displaying a stop aspect.

3.1.5.5 The number, position and alignment of loading / unloading indicators shall provide for unobstructed sighting and readability of at least one indicator at all times under conditions of clear visibility.



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Part 4 Layout of Signals: Aspect Sequences

4.1 Requirements for cautionary aspect sequences

4.1.1 Standard 3-aspect sequence

4.1.1.1 In 3-aspect colour light signalling areas, a first caution consisting of a single yellow aspect shall be displayed at the required signalling braking distance from the red aspect (see GK/RT0075).

4.1.1.2 The standard 3-aspect sequence shall be:

Green → Single yellow → Red

4.1.2 Standard 4-aspect sequence

4.1.2.1 In 4-aspect colour light signalling areas:

a) A first caution consisting of a double yellow aspect shall be displayed at the required signalling braking distance from the red aspect (see GK/RT0075), and

b) The red aspect shall also be preceded by a single yellow aspect displayed at the required signalling braking distance (see GK/RT0075).

4.1.2.2 The standard 4-aspect sequence shall be:

Green → Double yellow → Single yellow → Red

4.1.3 Non-standard 4-aspect sequences

4.1.3.1 By exception, the signalling system shall only display the following non-standard 4-aspect sequences, either:

a) A sequence incorporating two successive double yellow aspects, or

b) A sequence incorporating two successive single yellow aspects.

4.1.3.2 A sequence incorporating two successive double yellow aspects shall only be displayed where it is necessary to achieve the required signalling braking distance between the first double yellow aspect and the red aspect. In this case the non-standard 4-aspect sequence shall be:

Green → Double yellow → Double yellow → Single yellow → Red

4.1.3.3 A sequence incorporating two successive single yellow aspects shall only be displayed where it is necessary to provide the required signalling braking distance between the single yellow aspect and the red aspect in a 4-aspect sequence. In this case the non-standard 4-aspect sequence shall be:

Green → Double yellow → Single yellow → Single yellow → Red



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4.1.3.4 Where a non-standard 4-aspect sequence is provided, the train protection system (see GE/RT8075) shall be configured to mitigate the additional SPAD risk that arises:

a) At the signal that displays the single yellow aspect as part of the non-standard 4-aspect sequence incorporating two double yellow aspects, and

b) At the signal that displays the second single yellow aspect as part of the non-standard 4-aspect sequence incorporating two single yellow aspects.

4.1.3.5 Signal heads that do not display a double yellow aspect as part of a non-standard 4-aspect sequence shall retain the same signal head format as the 4-aspect signals in the sequence.

4.1.3.6 Where, in a non-standard 4-aspect sequence, the stop signal is a junction signal for which the diverging route is not approach controlled from red, sufficient distance shall be provided to the signal beyond the junction on the diverging route so that a train traversing the junction at the permissible speed can stop at that signal.

4.1.4 Cautionary aspect sequence transition methods: 3-aspect to 4-aspect signalling

4.1.4.1 The transition from a 3-aspect sequence to a 4-aspect sequence (including where an isolated 4-aspect signal is displayed within an otherwise 3-aspect sequence), shall be provided using either one of the following:

a) Transition method 1: Using a signal that displays a first caution for both of the next two stop signals.

b) Transition method 2: Using an additional 4-aspect distant signal.

c) Transition method 3: By configuring the first 4-aspect signal so that it is approach controlled from red when the next signal is displaying the red aspect.

4.1.4.2 Where transition method 1 is used (see Figure 2), the first 4-aspect signal (signal 5) shall display:

a) A 3-aspect sequence first caution when the next signal (signal 7) is displaying the red aspect, and

b) A 4-aspect first caution when the next signal (signal 7) is displaying the single yellow aspect and the next but one signal (signal 9) is displaying the red aspect.

4.1.4.3 Where transition method 1 is used, the train protection system shall be configured to mitigate the additional SPAD risk at the signal that displays the red aspect at the end of the last 3-aspect sequence (signal 7).

4.1.4.4 The particular signalling braking requirements for 3-aspect to 4-aspect transitions at converging junctions (where attainable speed is a factor) are set out in GK/RT0075.



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3asp 3asp 4asp 4asp 4asp 4asp 4asp

1 3 5 7* 9 11 13

* Train protection system (eg TPWS) required at this signal (No. 7)

G

G

G

G

G

G

G

Y

Y

Y

Y

Y

Y

R

R

R

R

R

YY

YY

YY

YY

YY

Figure 2 Example of a 3-aspect to 4-aspect transition using transition method 1

4.1.4.5 Where transition method 2 is used (see Figure 3), an additional 4-aspect distant signal (signal 7) shall be provided within the transition sequence at the required signalling braking distance (see GK/RT0075) and the signalling system shall be configured so that all of the following apply:

a) The first 4-aspect signal (signal 5) does not display a single yellow aspect.

b) The first 4-aspect signal (signal 5) displays the 4-aspect first caution when the next signal (signal 7) is displaying the single yellow aspect and the next but one signal (signal 9) is displaying the red aspect.

c) The additional 4-aspect distant signal (signal 7) displays the appropriate cautionary aspects relevant to the standard 4-aspect sequence. This signal does not display a red aspect.

3asp 3asp 4asp

Additional

distant signal

4asp 4asp 4asp

1 3 5

7

9 11 13

G

G

G

G

G

G

Y

Y

Y

Y

Y

R

R

R

R

YY

YY

YY

YY

YY

G

4asp




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4.1.4.6 Where transition method 3 is used (see Figure 4), the first 4-aspect signal (signal 7) shall be:

a) Approach controlled from red when the next signal (signal 9) is displaying the red aspect, and

b) Display an unrestricted double yellow aspect when the next signal is not displaying the red aspect.

3asp 3asp 3asp 4asp 4asp 4asp 4asp

1 3 5 7 9 11 13

G

G

G

G

G

Y

Y

Y

Y

Y

R

R

R

R

YY

YY

YY

YY

G

Y R

#1

#1: approach control condition


4.1.5 Cautionary aspect sequence transition methods: 4-aspect to 3-aspect signalling

4.1.5.1 Signals that display the first caution aspect in the 3-aspect sequence shall not have the appearance of a 4-aspect signal, except where the transition occurs at a 4-aspect junction signal where only the diverging route(s) incorporates the 4-aspect to 3-aspect transition.

4.1.5.2 Where the transition occurs at a 4-aspect junction signal and only the diverging route(s) incorporate the 4-aspect to 3-aspect transition, the junction signal shall display a green aspect when the next signal on the diverging route(s) is displaying a single yellow aspect as part of a 3-aspect sequence.

4.1.6 Semaphore and semaphore equivalent aspect sequences

4.1.6.1 Where semaphore signalling or semaphore equivalent colour light signalling is provided, the distant signal shall be configured to:

a) Display the relevant cautionary aspect when any of the associated stop signals are displaying a stop aspect, and

b) Only display a proceed aspect when all of the associated stop signals (to which the distant signal applies), are displaying an OFF aspect.

4.1.6.2 When the distant signal is ON because the second (or subsequent) signal in the associated sequence of stop signals is displaying a stop aspect, the first stop signal in the sequence shall display a stop aspect until the approaching train is detected to be nearly at a stand at that stop signal.



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4.1.6.3 Where the next signal beyond a semaphore distant signal is a semaphore stop signal to which the distant signal does not apply, a repeat semaphore distant signal arm shall be provided in association with that signal.

4.1.7 Aspects displayed by colour light signals that do not have main routes reading up to them

4.1.7.1 In 4-aspect colour light signalling areas, a stop signal that does not have a main route reading up to it shall display the following OFF aspects:

a) When the next signal ahead is displaying the red aspect, it shall display the single yellow aspect, and

b) When the next signal ahead is displaying the single yellow aspect, it shall display either:

i) The double yellow aspect, or

ii) The green aspect, only if the signalling braking distance between the next two stop signals is compatible with the attainable speed of the train (see GK/RT0075).

4.1.8 Approach lit colour light signals

4.1.8.1 Approach lit colour light signals shall only extinguish the signal aspect when:

a) The signal does not define the start or end of a movement authority that could be approached by a signalled train movement, and

b) The signal does not contribute to the sighting of signals within the signalling layout.

4.1.9 Cautionary aspect sequence approaching a points indicator

4.1.9.1 Except where all trains start from rest within sight of the points indicator, a caution aspect shall be displayed at the required signalling braking distance from the points indicator (see GK/RT0075), using either one of the following signals:

a) A distant board, or

b) A semaphore distant signal arm fixed in the ON position.

4.1.10 Cautionary aspect sequence approaching a stop board

4.1.10.1 Except where a stop board is only approached by a shunting movement or where all trains start from rest within sight of the stop board, a caution aspect shall be displayed at the required signalling braking distance from the stop board (see GK/RT0075), using any one of the following:

a) A distant board.

b) A semaphore distant signal displaying the caution aspect.

c) A colour light signal displaying a single yellow aspect.

d) A level crossing warning sign provided in accordance with GK/RT0192.



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4.1.11 Cautionary aspect sequence approaching a buffer stop at the end of a signalled route

4.1.11.1 Except on lines with ETCS cab signalling, a cautionary aspect sequence shall be displayed at the required signalling braking distance (see GK/RT0075) on the approach to the buffer stop at the end of main signal routes. The cautionary aspect sequence shall be displayed using one of the following:

a) An aspect sequence appropriate to the prevailing type of signalling, where the stop aspect is displayed by the buffer stop.

b) A distant board.

c) A semaphore distant signal arm fixed in the ON position.

d) An isolated colour light distant signal displaying a signal yellow aspect.

4.1.12 Cautionary aspect sequences at transitions between signalling systems

4.1.12.1 Within the transition zone between different types of lineside signalling systems, the sequence of displayed signal aspects and indications shall be compatible with:

a) The sequence of aspects leading up to the stop signal at the end of the signalled movement authority that is displayed by the other signalling system, and

b) The permissible speed associated with the movement authority.

4.2 Requirements for banner repeating signal aspects

4.2.1 Splitting banner repeating signal aspect sequences

4.2.1.1 Splitting banner repeating signals shall only be provided where:

a) A banner repeating signal is required on the approach to a junction signal, and

b) It is necessary to distinguish between an OFF banner aspect for different routes at the diverging junction.

4.2.1.2 Splitting banner repeating signals shall only be configured to display an OFF aspect for more than one diverging route if the associated diverging routes:

a) Have permissible speeds that do not differ by more than 10 mph, and

b) Do not differ in any characteristic that could affect operational safety.

4.2.1.3 Splitting banner repeating signals shall incorporate two banner repeating signal heads.

4.2.1.4 The dimension between the centre of the two signal heads of a splitting banner repeating signal shall be:

a) 1000 mm (+/- 100 mm) in the horizontal plane, and

b) 500 mm (+/- 50 mm) in the vertical plane, except where there is no obvious straight ahead route at the junction, in which case the two signal heads shall be positioned at the same level.



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Part 5 Layout of Signals: Junction Signalling

5.1 Requirements for route indications

5.1.1 Provision of route indicators

5.1.1.1 Junction signals shall display each required route indication as part of the signal aspect, using one of the following arrangements:

a) A position light junction indicator.

b) An alphanumeric junction indicator.

c) A position light junction indicator in combination with an alphanumeric route indicator.

5.1.2 Display of route indications

5.1.2.1 Junction signals shall display a route indication for all diverging routes.

5.1.2.2 Junction signals shall only display one position light junction indication at a time.

5.1.2.3 Where a position light junction indicator is provided, a route indication shall be displayed for all routes at a diverging junction where either:

a) There is no geographically obvious straight ahead route, or

b) The straightest alignment through the junction is an unsignalled route.

5.1.2.4 Where an alphanumeric route indicator is provided with a colour light signal or semaphore main stop signal, a route indication shall be displayed for the straight ahead route at a diverging junction where either:

a) There is no geographically obvious straight ahead route.

b) The permitted speed for the straight ahead route is less than 10 mph above that for any diverging route.

c) One or more of the routes leads to a station platform.

5.1.2.5 An alphanumeric route indication shall be displayed in conjunction with all position light subsidiary signal OFF aspects unless there is only one subsidiary route to which the signal applies and that route does not end at a limit of shunt signal.

5.1.2.6 An alphanumeric route indication shall be displayed in conjunction with all independent position light signal OFF aspects except that no route indicator is required if:

a) There is only one route from the signal and that route does not end at a limit of shunt signal, and

b) There is more than one route, where all of the following apply:

i) None of the routes end at a limit of shunt signal.

ii) None of the routes end at a signal where the consequence of a SPAD could be a serious hazard.

iii) There is no significant difference in the distances to the next signals.



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iv) The infrastructure characteristics for each route are similar in nature.

v) No safety hazard will arise if the train proceeds along an incorrect route.

5.1.2.7 Where alternative routes are available from a junction signal to the same destination, a common route indication shall be displayed by that signal for each of the routes only if both of the following apply:

a) The difference in permissible speed for each alternative route is not more than 10 mph, and

b) There is no difference between the routes in terms of infrastructure characteristics.

5.1.2.8 Where more than one signal is configured to display an alphanumeric route indication to a particular destination (for example, a station platform), the same alphanumeric indication shall be displayed by each of the signals.

5.1.2.9 The same alphanumeric route indication shall not be displayed by separate signals for movements towards different destinations at any one locality.

5.1.3 Configuration of signal OFF aspects and route indications

5.1.3.1 The position of junction signals shall, if practicable, be such that the driver of an approaching train can read the route indicator at the same time as the associated OFF aspects.

5.1.3.2 If the position of the junction signal is such that the driver of an approaching train cannot read the route indicator at the same time as the OFF aspects, then the junction signal shall be approach controlled from red, except:

a) Where flashing aspect sequences are provided and the approaching train is detected to be in a position that is compatible with the required reading time of the junction distant signal that displays the flashing single yellow aspect, and

b) Where splitting distant signals are provided and the approaching train is detected to be in a position that is compatible with the required reading time of the splitting distant signal immediately preceding the junction signal.

5.1.4 Provision of preliminary route indicators

5.1.4.1 A preliminary route indicator shall only be provided:

a) To enhance the standard junction signalling arrangements set out in 5.2, and

b) Where the junction signal is fitted with a position light junction indicator.

5.1.4.2 Where provided, preliminary route indicators shall be positioned:

a) Between the junction distant signal and the associated junction signal, and / or

b) By exception, on the approach to the junction distant signal, but not within the minimum reading distance for that signal.

5.1.4.3 The displayed preliminary route indication shall be compatible with the position light junction indication displayed by the junction signal.



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5.1.4.4 The signalling system shall be configured so that the preliminary route indicator shall only display an indication when all of the following apply:

a) The associated junction signal is displaying an OFF aspect.

b) Any signals positioned between the preliminary route indicator and the junction signal are displaying an aspect sequence that is compatible with the junction signal OFF aspect.

c) The driver will have at least 4 s reading time on the approach to the preliminary route indicator.

5.1.4.5 When the junction signal is displaying an OFF aspect, the junction distant signal shall only display the associated OFF aspect when:

a) The preliminary route indicator is displaying the required indication, and

b) Where the preliminary route indicator is on the approach to the junction distant signal, the approaching train has not passed the point that provides the minimum reading time for the preliminary route indicator.

5.2 Junction signalling: colour light signal aspect sequences

5.2.1 Colour light signal aspects displayed at diverging junctions

5.2.1.1 The sequence of colour light signal aspects and route indications approaching diverging junctions shall use one of the methods set out in Table 1.

Method Description Section

1 An unrestricted aspect displayed at the junction signal with the normal 3- or 4-aspect sequence displayed on the approach

5.2.2

2 Flashing yellow cautionary aspect sequence with a free single yellow at the junction signal

5.2.3

3 Approach control from red at the junction signal with the normal 3- or 4-aspect sequence displayed on the approach

5.2.4

4 A free single yellow at the junction signal with the normal 4-aspect sequence displayed on the approach

5.2.5

5 A splitting distant cautionary aspect sequence with an unrestricted aspect displayed at the junction signal

5.2.6

Table 1 Methods of junction signalling

5.2.1.2 Where the risk of reading through at an approach controlled junction signal (that is to say, method 3 or method 4 in Table 1) is unacceptable, the first signal beyond the junction on the straight ahead route and any other diverging route shall be maintained at its most restrictive aspect until the train has passed the junction signal.



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5.2.2 Junction method 1: Unrestricted aspect sequence

5.2.2.1 The signalling system shall only display a standard 3- or 4-aspect sequence and an unrestricted aspect at the junction signal when both of the following apply:

a) The difference between the permissible speeds of the straight ahead and diverging routes through, and immediately beyond, the junction is 10 mph or less, and

b) No safety hazard would arise if the train is wrongly routed at the junction (for example, gauge or traction supply incompatibility).

5.2.3 Junction method 2: Flashing yellow aspect sequence

5.2.3.1 Junction method 2 shall only be used where all of the following apply:

a) The speed reduction to the permissible speed at the point of divergence falls within the ranges set out in Table 2.

b) The divergence is not into a terminal line.

c) There is no operational requirement to reduce the speed of the train at the junction.

Permissible speed approaching the

diverging junction

Permissible speed at the

point of divergence

80 mph – 125 mph 40 mph or greater

40 mph – 75 mph 25 mph – 40 mph

Table 2 Speed ranges for flashing aspect sequences

5.2.3.2 Where a flashing yellow aspect sequence is displayed and 3-aspect colour light signalling is provided, the signalling system shall be configured so that:

a) A single flashing yellow aspect is displayed by the junction distant signal, and

b) A single yellow aspect is displayed by the junction signal.

Green → Flashing Single Yellow (#1) → Single Yellow (#2)

#1 Junction distant signal

#2 Junction signal

5.2.3.3 Where a sequence of flashing yellow aspects is displayed and 4-aspect colour light signalling is provided, the signalling system shall be configured so that:

a) A flashing double yellow aspect is displayed by the junction outer-distant signal (except where 5.2.3.4 applies).

b) A flashing single yellow aspect is displayed by the junction distant signal, between the flashing double yellow aspect and the single yellow aspect.

c) The single yellow aspect is displayed by the junction signal.



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Green → Flashing Double Yellow (#3) → Flashing Single Yellow (#2) → Single Yellow (#1)

#1 Junction signal

#2 Junction inner distant signal

#3 Junction outer distant signal

5.2.3.4 By exception, only when the junction outer distant signal is also a junction signal, the junction outer distant signal shall display a double yellow aspect on the approach to a flashing yellow aspect at the junction inner distant signal.

Green → Double Yellow (#3) → Flashing Single Yellow (#2) → Single Yellow (#1)

#1 Junction signal

#2 Junction inner distant signal

#3 Junction outer distant signal

5.2.3.5 The junction signal aspect shall change from a single yellow aspect to a less restrictive OFF aspect compatible with the aspect sequence beyond the diverging junction when the approaching train has passed the junction distant signal displaying the flashing single yellow aspect.

5.2.3.6 A flashing aspect sequence shall only be displayed when the approaching train is detected to be in a position that is compatible with the required reading time of the junction distant signal that displays the flashing single yellow aspect and one of the following applies:

a) The first signal beyond the diverging junction is a controlled stop signal that is either one of the following:

i) Displaying an OFF aspect.

ii) Displaying an ON aspect and a forward route is set.

iii) Displaying an ON aspect at the end of a loop line or platform line where all trains are expected to stop.

b) The first signal beyond the diverging junction is an automatic signal.

c) The first signal beyond the diverging junction is an isolated distant signal.

5.2.3.7 A flashing yellow aspect sequence shall only be applied to more than one diverging route at a junction signal, if both of the following apply:

a) The difference in permissible speed between the highest speed diverging route and the other diverging route(s) is not more than 10 mph, and

b) Any safety hazards or serious operational inconvenience arising from misrouting are common to all routes to which the flashing yellow aspects apply.

5.2.4 Junction method 3: Approach control from red

5.2.4.1 Where it is not appropriate to use a less restrictive method, the signalling system shall be configured to display a cautionary aspect sequence leading up to approach control from red at the junction signal.



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5.2.4.2 The junction signal shall display the red aspect until the approaching train is detected to have:

a) Passed the junction distant signal, and

b) Passed the banner signal (where provided with the junction signal), except where a splitting banner signal aspect is displayed.

5.2.4.3 When the approach control has been satisfied, the OFF aspect displayed at the junction signal shall be compatible with the aspect sequence on the diverging route.

5.2.5 Junction method 4: Approach control from single yellow

5.2.5.1 By exception, the signalling system shall only be configured to display the normal 4-aspect sequence leading up to a free single yellow at the junction signal, where all of the following apply:

a) It is not appropriate to use junction method 1 or junction method 2.

b) All rolling stock that operates over the route has a consistent braking characteristic (see GK/RT0075).

c) The signalling braking distances (see GK/RT0075) is compatible with the requirements for 4-aspect signalling between:

i) The junction distant signal that displays the double yellow aspect and the junction signal, and

ii) The junction signal and the first signals on all routes beyond the junction.

d) The braking performance of the rolling stock shall be compatible with:

i) The distance between the junction distant signal that displays the double yellow aspect and the point of divergence, and

ii) The required speed reduction to the permissible speed at the point of divergence.

e) The highest permissible speed for any route at the junction is 60 mph or less.

f) The difference in speed for the divergence is greater than 10 mph and not more than 30 mph.

5.2.5.2 When the diverging route is set:

a) The junction signal shall display the single yellow aspect, and

b) The junction distant signal shall display the double yellow aspect.

5.2.5.3 The junction signal shall continue to display the single yellow aspect until the train is detected to have both:

a) Passed the junction distant signal, and

b) Reached the sighting point of the junction signal from which the main signal aspect and junction indication are both readable.

5.2.5.4 When the approach control has been satisfied, the OFF aspect displayed at the junction signal shall be compatible with the aspect sequence on the diverging route.



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5.2.5.5 Free yellow aspects shall only be applied to more than one diverging route at a junction signal if there is no more than 10 mph difference in permissible speed between the highest speed diverging route and the other diverging route(s) under consideration.

5.2.6 Junction method 5: Splitting distant aspect sequence

5.2.6.1 By exception, the signalling system shall be configured to display a splitting distant aspect sequence leading to an unrestricted aspect at the junction signal.

5.2.6.2 A splitting distant aspect sequence shall only be displayed when the approaching train is detected to be in a position that is compatible with the required reading time of the junction distant signal.

5.2.6.3 When a splitting distant signal is also a stop signal, the red aspect shall only be displayed by the primary head.

5.2.6.4 When a signal aspect sequence is displayed that does not extend beyond the associated junction signal, the relevant OFF signal aspect shall only be displayed by the primary head.

5.2.6.5 Where a splitting distant signal is also a junction signal, the relevant route indication shall be displayed in association with the primary head.

5.2.6.6 The offset head shall illuminate only when the splitting distant signal is controlled to display an OFF aspect associated with the junction signal OFF aspect.

5.2.6.7 When the junction signal is displaying an OFF aspect, the following aspect sequence shall be displayed:

a) The junction signal shall display an aspect that is compatible with the aspect sequence displayed by the signals on the route set beyond the junction.

b) The inner splitting distant signal shall display:

i) A single yellow aspect, in the signal head that applies to the route(s) that is not set at the junction, and

ii) The signal aspect that is compatible with the OFF aspect displayed by the junction signal, in the signal head that applies to the route that is set at the junction.

c) Where provided, the outer splitting distant signal shall display:

i) A double yellow aspect, in the signal head that applies to the route that is not set at the junction signal, and

ii) A green signal aspect, in the signal head that applies to the route that is set at the junction.

5.2.6.8 A splitting distant aspect sequence shall only be applied to more than one diverging route at a junction signal, if both of the following apply:

a) The difference in permissible speed between the highest speed diverging route and the other diverging route(s) is not more than 10 mph, and

b) Any safety hazards or serious operational inconvenience arising from misrouting are common to all routes to which the splitting distant aspects apply.



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5.3 Junction signalling: semaphore signal aspect sequences

5.3.1 Semaphore signal aspects displayed at diverging junctions

5.3.1.1 The route set at a semaphore junction signal shall be indicated to the driver using one of the following:

a) Stepped multiple semaphore stop signal arms.

b) Stacked multiple semaphore stop signal arms.

Or

c) A standard alphanumeric route indicator in association with a single semaphore stop signal arm.

5.3.1.2 A semaphore junction distant signal shall display the ON aspect whenever the junction signal is displaying an OFF aspect for a diverging route, except where:

a) The permissible speed of the diverging route is not more than 10 mph below the permissible speed of the straight route, and

b) No safety hazards or serious operational inconvenience will arise from misrouting.

5.3.1.3 Where an isolated splitting distant signal is provided in association with a semaphore junction signal in absolute block signalling areas, the splitting distant signal shall not display a stop aspect.

5.3.1.4 Where a signal on the approach to a semaphore junction signal also conveys an indication of the route to be taken at the junction, all intervening signals shall also display equivalent route information.

5.4 Junction signalling: AWS requirements

5.4.1 Requirements for Automatic Warning System (AWS) at junction signals

5.4.1.1 A junction signal that is approach controlled from red shall display the OFF aspect before the approaching train reaches the Automatic Warning System (AWS) magnet (see GE/RT8075), unless another condition means that an OFF aspect cannot be displayed.

5.4.1.2 A junction signal that is approach controlled from yellow (either as part of a flashing yellow aspect sequence, or as a free yellow aspect) shall clear to a less restrictive OFF aspect that is compatible with the aspect sequence beyond the junction before the approaching train reaches the AWS magnet, unless another condition means that a less restrictive OFF aspect cannot be displayed.

5.5 Junction signalling: prohibited aspects

5.5.1 Prohibited signal aspect sequences at junctions

5.5.1.1 The signalling system shall be configured so that the following aspect combinations are not used to display movement authorities:

a) (Junction method 2) A flashing single yellow aspect immediately preceded by a signal also displaying the flashing single yellow aspect.



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b) (Junction method 2) A flashing double yellow aspect immediately preceded either:

i) By a signal displaying the flashing single yellow aspect, or

ii) By a signal also displaying the flashing double yellow aspect.

c) (Junction method 2) A flashing double yellow aspect immediately followed by a signal displaying any other aspect than the flashing single yellow aspect.

d) (Junction method 2) Consecutive or overlapping flashing aspect sequences that apply to more than one junction signal.

e) (Junction method 2) Any aspect sequence incorporating a flashing colour light signal aspect and a semaphore signal.

f) A free yellow aspect sequence (junction method 4) and a flashing yellow signal aspect sequence (junction method 2) for different routes from the same junction signal.

g) A flashing aspect sequence (junction method 2) and a splitting distant signal aspect sequence (junction method 5) for different routes from the same junction signal.

h) (Junction method 5) A splitting distant signal shall not display a flashing aspect.



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Part 6 Layout of Signals: Bi-directional Signalling

6.1 Bi-directional signalling

6.1.1 Provision of signals

6.1.1.1 Where full bi-directional signalling facilities are provided for every signal along a multiple track route, there shall be a parallel positioning of signals on adjacent lines in accordance with GE/RT8037.

6.1.1.2 Where reduced capacity bi-directional signalling facilities are provided:

a) Consecutive contraflow direction stop signals shall be spaced no more than 10 miles (16 km) apart, and

b) Contraflow direction stop signals and distant signals shall be positioned so that there is a parallel signal provided for movements in the same direction on adjacent line(s). (GE/RT8037 sets out other requirements for the positioning of parallel signals.)

6.1.1.3 Where bi-directional facilities are provided on a line signalled using 4-aspect colour light signals for the predominant (normal) direction of traffic, a 3-aspect sequence shall only be provided for movements in the contraflow direction if a lower permissible speed is used to accommodate the reduced signalling braking distances between 3-aspect signals that display the yellow and red aspects.



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Part 7 Degraded Signalling

7.1 Degraded colour light signalling

7.1.1 Aspects to be displayed when a colour light signal light fails

7.1.1.1 Failure of illumination of the most restrictive aspect in a colour light signal shall:

a) Prevent the display of proceed signal aspects towards the defective signal, and

b) Cause the associated distant signal to display its most restrictive aspect.

7.1.1.2 Junction signals shall display a red aspect and be approach controlled from red either:

a) If the signal that is required to display the associated single flashing yellow aspect fails to commence flashing, or subsequently fails, or

b) If the splitting distant signal immediately preceding the junction signal fails to display the correct aspect or subsequently fails.

7.1.2 Proceed on sight signalling

7.1.2.1 The requirements for displaying signal aspects for train movements into signal sections that are affected by lineside signalling failures are set out in GE/RT8071.



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Part 8 Application of this document

8.1 Application - infrastructure managers

8.1.1 Scope

8.1.1.1 The requirements in Part 2 of this document apply to all new signal, route indicator and signalling indicator equipment used for displaying movement authority information to train crew and station dispatchers.

8.1.1.2 The requirements in Parts 2, 3 and 6 of this document apply to all work that affects the layout and functionality of signals, whether new or alteration.

8.1.1.3 The requirements in Parts 4, 5 and 7 of this document apply to all work that affects the layout and functionality of signals, whether new or alteration, except that action to bring existing interlockings into compliance with this standard is not required, provided that they were compliant with the standards applicable at the time that they were brought into service. When it is known, or becomes known, that existing interlockings do not comply with the requirements of this document, action to bring them into compliance is required when the signalling installation as a whole is renewed. It is permissible for a complete interlocking to be renewed on a ‘like-for-like’ basis, that is to say, commensurate with the standards that were in force at the time of its original installation.

8.1.1.4 It is permissible for the infrastructure manager to designate specific infrastructure projects, ongoing when this document comes into force, for which compliance with the requirements of this document applicable to the design, construction and commissioning of new or altered infrastructure is not mandatory. When designating such projects, the infrastructure manager shall consider:

a) Its responsibilities under its current safety authorisation.

b) The stage reached by the project at the time this document comes into force (for example, approval in principle).

c) Whether compliance is necessary to ensure compatibility with other parts of the infrastructure.

d) Whether compliance is necessary to facilitate safe interworking having regard to changes to related requirements mandated on another infrastructure manager or a railway undertaking.

e) The economic impact of compliance, but subject to its current safety authorisation in relation to the infrastructure in question.

8.1.1.5 Action to bring existing signals, indicators and signalling layouts into compliance with the requirements of this document is not required.

8.1.2 Exclusions from scope

8.1.2.1 There are no exclusions from the scope specified in 8.1.1 for infrastructure managers.

8.1.3 General compliance date for infrastructure managers

8.1.3.1 This Railway Group Standard comes into force and is to be complied with from 07 March 2015.



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8.1.3.2 After the compliance dates, or the date by which compliance is achieved if earlier, infrastructure managers are to maintain compliance with the requirements set out in this Railway Group Standard. Where it is considered not reasonably practicable to comply with the requirements, authorisation not to comply should be sought in accordance with the Railway Group Standards Code.

8.1.4 Exceptions to general compliance date

8.1.4.1 There are no exceptions to the general compliance date specified in 8.1.3 for infrastructure managers.

8.2 Application - railway undertakings

8.2.1 There are no requirements applicable to railway undertakings.

8.3 Health and safety responsibilities

8.3.1 Users of documents published by RSSB are reminded of the need to consider their own responsibilities to ensure health and safety at work and their own duties under health and safety legislation. RSSB does not warrant that compliance with all or any documents published by RSSB is sufficient in itself to ensure safe systems of work or operation or to satisfy such responsibilities or duties.



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Appendix A Positioning Criteria for Stop Signals on Electrified Lines

The requirements specified in this appendix are mandatory

A.1 Positioning stop signals on lines fitted with overhead electrification systems

A.1.1 Assessment of train stopping position relative to stop signals and overhead line features

A.1.1.1 During the design of infrastructure positioning an assessment shall be made of:

a) Electric trains formed of rolling stock authorised to operate over the route.

b) The positioning of raised pantographs that interface between the electric traction unit and the overhead line equipment above, in all permitted train configurations.

c) All permissible stopping distances between a signal, or movement stop marker, and the front of the train.

d) Proposed or existing location of a stop signal or movement stop markers.

e) Proposed or existing location of overhead line features and associated pantograph exclusion zones.

f) Requirement for trains to stop at signals in accordance with the GE/RT8000 Rule Book.

g) Acceleration of the train from rest, towards the proposed or existing location of overhead line features and associated pantograph exclusion zones.

A.1.1.2 Duty holders shall cooperate in the provision of the data set out in A.1.1.1. This is essential to ensure damage to train or overhead line equipment (OLE) (including potential pantograph damage and dewirement) does not result from train and infrastructure incompatibility.

A.1.2 Position of stop signals relative to OLE neutral sections

A.1.2.1 For trains fitted with a single pantograph, after assessment of the issues set out in A.1.1.1, stop signals, or movement stop markers (or OLE) shall be positioned so that the pantograph does not come to rest in an OLE neutral section or the associated pantograph exclusion zone.

A.1.2.2 Where a neutral section is situated on the approach to a location where trains are required to stop, the stop signal spacing, or movement stop marker spacing, shall be adequate to ensure that the pantograph does not come to rest in an OLE neutral section or a pantograph exclusion zone.

A.1.2.3 For trains fitted with multiple pantographs, an assessment of the issues set out in A.1.1.1 for trains fitted with a single pantograph, shall first be made. Stop signals, or movement stop markers (or OLE) shall then be positioned; ensuring not more than one pantograph comes to rest in an OLE neutral section or the associated pantograph exclusion zone.



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A.1.2.4 Where trains are required to stop on the approach side to the neutral section, the stop signal, or stop signals, or movement stop marker spacing, shall be adequate to ensure:

a) Subsequent train movement through the overhead line (OHL) neutral section is not prevented, and

b) Correct operation of automatic power control systems.

A.1.3 Position of stop signals relative to other critical OLE features

A.1.3.1 Stop signals and OLE shall not be located such that signal sighting is impaired.

A.1.3.2 After assessment of the issues set out in A.1.1.1, stop signals, or movement stop markers (or OLE) shall be positioned so that any raised pantograph does not come to rest, or pass at slow speed, beneath any part of pantograph exclusion zones associated with an:

a) OLE section insulator.

b) OLE switched booster overlap.

c) OLE booster overlap.

d) OLE construction overlap.

A.1.3.3 Where stop signals, or movement stop markers (or OLE) are associated with only occasional diversionary movements, and there is conflict at an OLE overlap location, as set out in A.1.3.2, it is permissible for alternative protective provisions to be adopted where design assessment has shown an alternative location is not reasonably practicable. In every case where alternative protective provisions have been adopted, a design risk assessment shall be retained and the mitigating measure recorded in the Infrastructure Register.

A.2 Positioning stop signals on lines fitted with conductor rail electrification systems

A.2.1 Assessment of train stopping position relative to stop signals and conductor rail electrification system features

A.2.1.1 During the design of infrastructure positioning, an assessment shall be made of:

a) Electric trains formed of rolling stock authorised to operate over the route.

b) The positioning of collector shoes that interface with third rails and, when applicable, fourth rails, in all permitted train configurations.

c) All permissible stopping distances between a signal, or movement stop marker, and the front of the train.

d) The proposed or existing location of a stop signal or movement stop markers.

e) The proposed or existing location of conductor rail gaps.

f) The proposed or existing arrangement for remote switching between sections of conductor rail.

g) The requirement for trains to stop at signals in accordance with the GE/RT8000 Rule Book.



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h) Acceleration of the train from rest, towards the proposed or existing location of conductor rail gaps.

A.2.1.2 Duty holders shall cooperate in the provision of data set out in A.2.1.1. This is essential to ensure trains are not gapped and risk of fire, risk of arc induced injury, or damage to trains or fixed infrastructure, does not result from train and infrastructure incompatibility.

A.2.2 Position of stop signals relative to conductor rail gaps

A.2.2.1 After assessment of the issues set out in A.2.1.1, stop signals, or movement stop markers (or conductor rails) shall be positioned to ensure any conductor rail collector shoes do not come to rest in a conductor rail gap.

A.2.2.2 After assessment of the issues set out in A.2.1.1, stop signals, or movement stop markers (or conductor rails) shall be positioned to ensure conductor rail collector shoes do not bridge a gap between two (or more) sections of conductor rail that can be isolated from each other by remote switching.



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Definitions

Cautionary aspect / cautionary aspect sequence

The signal aspects displayed by the signals, either on the approach to a junction signal displaying a restrictive aspect, or any signal displaying a stop aspect.

Centre line (of signal or indicator)

The line (usually extending out perpendicularly from the face of a signal) forming the optical axis of the beam.

Chromaticity (for lights only)

The co-ordinates of a colour that may be plotted on the 1931 CIE (Commission Internationale de l’Eclairage) chromaticity diagram to graphically represent the colour.

Correctly displayed (signal aspect or indication)

The accurate display of movement authority information so that the railway operator is able to observe the information that the system is designed to display.

Displayed / displaying (signal aspect or indication)

Visual presentation (by means of lineside signalling equipment) of movement authority information to a railway operator (typically train crew or station staff).

Distant / inner distant signal

A signal that displays the cautionary aspect approaching a stop signal.

Diverging junction

A junction that incorporates facing points and signalled routes in more than one facing direction.

Diverging route

Any route at a facing junction that is not designated the ‘straight ahead route’.

Independent single line

A line that forms a distinct single line route and is signalled for train movements in both directions.

Junction distant signal

A signal that displays the cautionary signal aspect on the approach to a junction signal.

Junction outer-distant signal

A signal that displays the first cautionary aspect in a sequence of cautionary aspects on the approach to a junction signal.

Junction signal

A colour light signal or semaphore stop signal that is configured to display signal aspects for more than one route at a diverging junction.

Lower quadrant

A term applied to a semaphore signal, in which the OFF aspect is displayed when the left-hand end of the signal arm is lowered below the horizontal.

Movement authority (MA)

The authority given by a signaller (or ground frame operator), issued via the signalling system to the driver, which is the authority to move the train within defined limits.



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OFF aspect

Any signal aspect that is less restrictive than an ON aspect displayed by a particular signal.

ON aspect

The most restrictive signal aspect that can be displayed by a particular signal.

Outer distant signal

A signal that displays the first cautionary aspect in a sequence of cautionary aspects on the approach to a stop signal.

Pantograph exclusion zone

The length of track relative to a defined overhead line equipment feature (for example, an overlap) within which the pantograph of an electric train does not touch the contact wire when the train is stationary or moving at a slow speed in order to prevent electrical arcing.

Reading through

The erroneous observance and response to a signal aspect beyond the signal that the driver is required to observe.

Signal

Fixed infrastructure equipment that is positioned at the lineside and used by the infrastructure manager to display information about movement authorities to railway undertakings.

Signal light

The part of a signal that emits an illuminated form of visual indication. A signal aspect can incorporate one or more signal lights.

Signal primary identification

The signal identification that is displayed at the signal when a signal has more than one numbered operating device.

Signal red, signal yellow, signal green, signal blue, signal white, lunar white

Throughout this document these light colour descriptions correspond to the appropriate colour definition in Appendix B of this document.

Signalling indication

A form of operational information that is displayed by lineside indicators.

Stop signal

Any signal that can display a stop aspect.

Straight ahead route

The non-diverging (and usually the fastest) route at a diverging junction.

Synchronism (for lights only)

The illumination of multiple flashing lights, so that all of the lights are displayed at the same time.

Upper quadrant

A term applied to a semaphore signal, banner repeating signal or position light signal, in which the OFF aspect is displayed when the left-hand end of the signal arm is raised above the horizontal.



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Abbreviations and acronyms AWS

Automatic Warning System

LED

Light emitting diode

OHL

Overhead line

OLE

Overhead line equipment

SPAD

Signal passed at danger

TPWS

Train Protection and Warning System



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References

The Catalogue of Railway Group Standards gives the current issue number and status of documents published by RSSB. This information is also available from www.rgsonline.co.uk.

RGSC 01 Railway Group Standards Code

RGSC 02 Standards Manual

Documents referenced in the text

Railway Group Standards

GC/RT5021 Track System Requirements

GE/RT8000 Rule Book

GE/RT8030 Requirements for the Train Protection and Warning System (TPWS)

GE/RT8035 Automatic Warning System (AWS)

GE/RT8037 Signal Positioning and Visibility

GE/RT8071 Proceed-on-Sight Authorities

GE/RT8075 AWS and TPWS Interface Requirements

GE/RT8270 Assessment of Compatibility of Rolling Stock and Infrastructure

GI/RT7006 Prevention and Mitigation of Overruns – Risk Assessment

GK/RT0044 Permissive Working

GK/RT0051 Single Line Control

GK/RT0055 Block System Interface Requirements

GK/RT0057 Lineside Signal and Indicator Product Design and Assessment Requirements

GK/RT0058 Lineside Signal Aspect and Indication Requirements

GK/RT0075 Lineside Signal Spacing and Speed Signage

GK/RT0077 Ground Frames and Shunters’ Releases

GK/RT0192 Level Crossing Interface Requirements

GK/RT0212 Signalling Lockout Systems to Protect Railway Undertaking Personnel

GO/RT3215 Requirements for the Weekly Operating Notice, Periodical Operating Notice and Sectional Appendix

Information Handbook RS/521 Signals, handsignals, indicators and signs handbook

RSSB documents

GK/GN0645 Guidance on Lineside Signals, Indicators and Layout of Signals

Other relevant documents

Other references

BS 381C: Colour Chart

BS 1376, 1974: Specification for Colour of Light Signals

BS 873, Part 6: Specification for retroreflective and non-retroreflective signs

Traffic Signs and Signals Guidance, published by the Department for Transport


