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Uncontrolled When Printed Railway Group Standard
GK/RT0032
Issue Two
Date February 2002
Provision of
Lineside Signals
Synopsis
This document defines the mandatory
requirements for the provision of
lineside signals and the sequences in
which signal aspects shall be
presented to train drivers, in respect of
plain line, diverging junctions and for
bi-directional lines.
Signatures removed from electronic version
Submitted by
Paul Woolford
Project Manager
Authorised by
Brian Alston
Controller, Railway Group Standards
This document is the property of
Railway Safety. It shall not be
reproduced in whole or in part without
the written permission of the Controller,
Railway Group Standards,
Railway Safety.
Published by:
Railway Safety
Evergreen House
160 Euston Road
London NW1 2DX
© Copyright 2002 Railway Safety
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Provision of Lineside Signals
Railway Group Standard
GK/RT0032
Issue Two
Date February 2002
Page 1 of 36
Contents
Section
Page
Part A
A1
A2
A3
A4
A5
A6
A7
Issue record
Implementation of this document
Scope of Railway Group Standards
Responsibilities
Health and safety responsibilities
Technical content
Supply
Part B
B1
B2
B3
B4
B5
B6
B7
B8
B9
B10
B11
B12
Purpose
Application of this document
Definitions
Principles
Provision of stop signals
Constraints on positioning of stop signals
Designation of main signals
Aspect sequences
Aspect sequence transitions
Junction signalling
Bi-directional signalling
Identity of signals
5
5
6
7
7
9
12
13
17
19
24
24
Transition from three to four aspect signalling
Interface with London Underground lineside signalling
Criteria for the selection of method of junction control
(colour light signalling)
Colour light splitting distant signals: Permissible arrangement of aspects
27
29
30
Appendices
1
2
3
4
References
RAILWAY SAFETY
Description
2
2
2
3
3
3
3
32
35
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Issue Two
Date February 2002
Page 2 of 36
Provision of Lineside Signals
Part A
A1 Issue Record
This document will be updated when necessary by distribution of a complete
replacement.
Issue
1
2
Date
October 1995
February 2002
Comments
Original Document
Replaces Issue 1
Supersedes RGS as shown in section A2
Issue 2 of this standard has been subject to extensive re-writing and therefore no
amendment bars have been inserted.
A2 Implementation of
this document
The publication date of this document is February 2002.
This document comes into force on 6 April 2002. The dates by which compliance
with the requirements of this document is to be achieved are set out in Part B2.
Where those dates are later than the date on which this document comes into
force, this is to give Railway Group members additional time to plan and
commence implementation so as to achieve full compliance by the dates set out
in Part B2.
This document supersedes the following Railway Group Standards, either in
whole or in part as indicated:
Railway
Group
Standard
Issue
No.
Title
RGS sections
superseded
GK/RT0032
issue 2
Date as of which
sections are
superseded
GK/RT0009
1
Identification
of Signalling
and Related
Equipment
Section 10
6 April 2002
GK/RT0031
3
Lineside
Signals and
Indicators
Section 5.2.2
(part)
6 April 2002
GK/RT0032
1
Lineside
Signal aspect
Sequences
All
6 April 2002
GK/RT0035
2
Layout of
Lineside
Signals
Sections 5, 8,
9, 10
6 April 2002
GK/RT0031 Issue 3, GK/RT0032 Issue 1 and GK/RT0035 Issue 2 are withdrawn
with effect from 6 April 2002.
A3 Scope of Railway
Group Standards
The overall scope of Railway Group Standards is set out in Appendix A of
GA/RT6001. The specific scope of this document is set out in Part B2.
2
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Issue Two
Date February 2002
Page 3 of 36
A4 Responsibilities
Railway Group Standards are mandatory on all members of the Railway Group*
and apply to all relevant activities that fall into 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 Railway Group Standards is determined by
the terms of the contract between the respective parties. Where a contractor is a
duty holder of a Railway Safety Case then Railway Group Standards apply
directly to the activities described in the Safety Case.
* The Railway Group comprises Railtrack PLC, Railway Safety, and the train and
station operators who hold railway safety cases for operation on or related to
infrastructure controlled by Railtrack PLC.
Railtrack PLC is known as Railtrack.
A5 Health and safety
responsibilities
In issuing this document, Railway Safety makes no warranties, express or
implied, that compliance with all or any documents published by Railway Safety 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.
A6 Technical content
The technical content of this document has been approved by:
Jeff Allan, Principal S&T Engineer, Railway Safety
Richard Evans, Principal, Operations, Railway Safety
Peter Williment, Principal, Electrification, Railway Safety
Enquiries should be directed to Railway Safety – Tel: 020 7904 7518
A7 Supply
Controlled and uncontrolled copies of this document may be obtained from the
Industry Safety Liaison Dept, Railway Safety, Evergreen House,
160 Euston Road, London NW1 2DX.
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Date February 2002
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Provision of Lineside Signals
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Issue Two
Date February 2002
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Part B
B1 Purpose
This document defines the mandatory requirements for the provision of lineside
signals and the sequences in which signal aspects shall be presented to train
drivers, in respect of plain line, diverging junctions and for bi-directional lines, to
enable them to:
a)
stop safely at a signal at danger
b)
regulate train speed to negotiate junctions safely
c)
regulate train speed to that of an immediately preceding train.
B2 Application of this
document
B2.1 To whom the requirements apply
This document contains requirements that are applicable to duty holders of the
infrastructure controller category of Railway Safety Case.
B2.2 Compliance requirements
B2.2.1 Infrastructure
The requirements of this document are mandatory for new Railtrack controlled
infrastructure and for alterations to existing Railtrack controlled infrastructure for
which approval in principle is given on or after 6 April 2002.
When approval in principle is given before 6 April 2002, but the infrastructure has
not yet been brought into service, the design shall be reviewed and, where
reasonably practicable, brought into line with the requirements of this document.
B2.2.2 General compliance requirements
Until 6 April 2002, or the date by which compliance is achieved (if earlier), the
applicable requirements of the predecessor documents shall continue to be met
(see Part A for details).
After 6 April 2002, or after the date by which compliance is achieved (if earlier),
Railway Group members shall not deviate from the requirements set out in this
document.
Where approval in principle is given on or after 6 April 2002, but it is considered
not reasonably practicable to comply with the requirements set out in this
document, authorisation not to comply shall be sought in accordance with
GA/RT6001, GA/RT6004 or GA/RT6006.
B2.3 Exclusions from the application of this document
Specifically the contents of this document apply to the design and operational use
of signalling systems, on infrastructure controlled by Railtrack that uses lineside
signals. It encompasses requirements governing the aspect sequences for
signalling on plain line, on the approach to diverging junctions and in respect of
bi-directional lines.
This document does not include:
RAILWAY SAFETY
a)
specifications for the visual and optical equipment to be used in signals (see
GK/RT0031)
b)
the requirements for the spacing of signals for compatibility with speeds,
gradients and train braking performance (see GK/RT0034)
c)
the requirements for the positioning of signals to ensure that they are visible
to drivers, and the provision of banner repeaters and co-acting signals (see
GK/RT0037)
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Provision of Lineside Signals
d)
specific requirements for signalling a train onto an occupied line (see
GK/RT0044)
e)
the methods of block signalling to be adopted for a section of line. These
are specified in the following Railway Group Standards:
GK/RT0041
GK/RT0042
GK/RT0051
GK/RT0054
f)
Track Circuit Block
Absolute Block
Single Line Control
Radio Electronic Token Block
requirements for the provision of two aspect (red/green) signalling systems
on metro-type railways.
B3 Definitions
Area of conflict
A section of line ahead of a signal at danger on which a head-on, crossing or
same direction converging collision with another legitimately positioned train
(whether moving or stationary) could occur in the event of the signal being
passed at danger. See also GI/RT7006.
Aspect sequence
The order in which the aspects of successive signals are displayed to the driver.
Closing up signal
A signal provided to enable a train to closely approach a platform during the time
when it is occupied by a departing train. A closing up signal may or may not form part
of the standard three or four aspect signalling sequence.
Contra-flow
The direction of traffic opposite to the normal direction of flow on bi-directional lines
where a predominant direction is specified.
Junction signal
A signal protecting any facing points over which more than one main route is
available.
In colour light signalled areas, the term junction signal also applies where there
are facing points ahead of the signal and the straight-ahead route is not a main
signalled route, although it might appear to the driver to be an available route.
Mid-platform signal
A signal provided to enable two trains to be positioned at a platform by the use of
block signalling techniques. A mid-platform signal may or may not form part of the
standard three or four aspect signalling sequence.
Required reading time
The sum of:
a)
b)
the time that is necessary for a driver approaching a signal to achieve the
following:
i)
identify the signal that is applicable to the driver
ii)
observe the information presented by the signal
iii)
interpret the information to determine what action, if any, is required
such additional reading time as is reasonably practicable to provide.
Both parts a) and b) of the required reading time are specific to each individual signal.
The concept of required reading time is not applicable where all trains start from rest.
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Issue Two
Date February 2002
Page 7 of 36
Signal designation
(The terms ‘Passable/Non-passable’ apply for operating purposes, and
‘Automatic/Controlled’ for signal control system purposes.)
Automatic: A signal which does not require specific action by a signaller or
automatic route setting equipment in order to show a proceed aspect.
Controlled: A signal that requires a specific action by a signaller or
automatic route setting equipment on each occasion that it is required to
show a proceed aspect (other than when a controlled signal is arranged to
work automatically).
Non-passable: A signal that protects an area of conflict or other
infrastructure such that a significant hazard would arise in the event of it
being passed at danger without authority. Such signals cannot be passed at
danger without specific authority from the signaller, in accordance with the
Rule Book
Passable: A signal which is able to be passed at danger without specific
authority from the signaller, in accordance with the Rule Book, without a
significant hazard arising.
Signal spacing (as applied to this document)
The distance between the signal or lineside sign displaying the first cautionary aspect
and the signal or lineside sign at which the train is required to stop.
Signal/stop signal
The word ‘signal’ includes not only colour light and semaphore signals, but also any
lineside sign that performs the function of a signal.
For the purposes of this document, the term stop signals also include shunting
signals, stop boards, buffer stops and points set indicators.
Standard three aspect sequence
The following colour light aspect sequence is referred to as a standard three aspect
sequence:
Green – Single Yellow – Red
Standard four aspect sequence
The following colour light aspect sequence is referred to as a standard four aspect
sequence:
Green – Double Yellow – Single Yellow – Red
Other defined terms are included in GK/RT0002.
B4 Principles
This document supports HMRI Safety Principle 20 – ‘Signalling – Safe routing,
spacing and control’.
B5 Provision of stop
signals
B5.1 Choice of signal type
B5.1.1 Running lines
A stop signal that controls a running direction movement along or onto a running
line shall be a main signal, except as permitted below.
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Provision of Lineside Signals
It is permissible for a shunting signal to be provided for the control of other than
timetabled passenger train movements, subject to consideration of the following
factors:
a)
the number and proportion of movements that proceed up to the signal
ahead on the running line
b)
the visibility of the signal ahead upon the movement reaching the running
line
c)
the distance to the signal ahead on the running line
d)
the number and proportion of movements proceeding onto a passenger line
that is already occupied.
It is permissible for such a shunting signal to become facing for running
movements (ie operated as a preset shunt) and be controlled in accordance with
GK/RT0060.
B5.1.2 Sidings
A stop signal controlling movements into or along sidings shall be a shunting
signal, unless other considerations require it to be a position light aspect on a
main signal.
B5.2 Block signalling
In all forms of fixed block working, the entrance and exit of every signal section
shall be denoted by a stop signal.
The method of block signalling in use shall be reviewed in the event of a
proposed change of operational use, to ensure that it is still consistent with the
criteria set out in GK/RT0041, GK/RT0042 and GK/RT0051.
B5.3 Facing junctions
A stop signal shall be provided on every line on which signalled movements can
approach facing points, with the exception of train operated points equipped with
points indicators (see section B6.1).
B5.4 Level crossings
Where a level crossing is required to be protected by interlocked signals (see
GI/RT7012), a stop signal shall be provided on every line on which signalled
movements approach the crossing.
B5.5 Conflicting movements
A stop signal shall be provided on every line on which signalled movements can
approach an area of conflict, including trailing points and other items of
infrastructure including movable bridges, so that:
a)
trains can be given movement authorities when movements are to be made
b)
trains not having a movement authority are stopped before reaching the
area of conflict.
B5.6 Lockout systems
Where a lockout system for the protection of trackside personnel is provided, a
stop signal shall be provided on every line on which signalled movements can
approach the area protected by the lockout system, positioned so as to protect
the personnel making use of the system.
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Date February 2002
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B5.7 Signals at point of reversal
B5.7.1
Where trains are required to reverse on lines worked by track circuit block or
absolute block, a stop signal (referred to in section B5.7.2 as the set-back signal)
shall be provided at the point of reversal to authorise the movement in the
reverse direction.
B5.7.2
Where practicable, the set-back signal shall be positioned so that:
a)
the whole of the train comes to a stand behind the signal after making the
outward movement
b)
when the outward movement has been completed, the distance between the
end of the train and the signal is minimised.
B5.7.3
It is permissible to provide a marker sign, such as a multiple-unit car stop or other
appropriate sign, at the outward stopping point to aid the driver. Such a sign shall
not be used to define the limit of movement authority for the outward movement.
B5.8 Ground frames
Signals on running lines protecting ground frames shall be controlled signals,
designated non-passable. It is permissible for movements from running lines into
or entirely within sidings accessed by ground frame operated points to be
controlled by handsignal.
B6 Constraints on
positioning of stop signals
B6.1 Position of signals relative to facing points
B6.1.1
Where a signal reads over facing points, it shall be positioned not more than
800 m from the first set of facing points, so that risk due to the following is
minimised:
a)
the likelihood of the driver forgetting the indicated route
b)
the ability to accelerate to greater than the permissible speed over the
diverging route.
B6.1.2
The 800 m limit does not apply in respect of any of the following:
a)
points which are operated from a ground frame
b)
a signal which is positioned parallel with other signals, one of which is within
800 m of facing points, and other factors prevent the positioning of all
signals closer to the junction (see GK/RT0037)
c)
facing points which are in the same position for all movements from the
signal (eg, at the entrance to unidirectional passing loops)
d)
facing points which are secured out of use
e)
as a temporary consequence of stageworks. In such circumstances an
appropriate warning shall be published to drivers using the route during the
stageworks.
B6.2 Position of signals relative to points and level crossings
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Provision of Lineside Signals
Where practicable, stop signals shall be positioned so that:
a)
the associated overlap is clear of points, level crossings and other moveable
infrastructure
b)
trains stopped at the signal do not stand over points or level crossings or
foul any other line. This necessitates taking into account the stopping
positions(s) of trains relative to the signal and the lengths of trains
authorised to operate on the route.
Stop signals shall be positioned so that trains stopped at them do not stand over
runaway catch points.
B6.3 Position of stop boards
Where authority is required to pass a stop board, it shall be positioned such that
the authority can be given from the usual working place of the shunter or
person-in-charge. Where this is not practicable one of the following options shall
be adopted:
a)
A means of direct communication (ie telephone or radio) between drivers
and the shunter, signaller or person-in-charge shall be provided.
b)
The stop board shall be replaced by a signal.
B6.4 Position of signals relative to platforms
Stop signals shall be positioned to minimise the risk arising from passenger trains
without central door locking or power operated doors stopping with a platform
adjacent to only part of the train. See also GK/RT0037.
B6.5 Position of signals relative to hazardous locations
B6.5.1
Where practicable, stop signals shall be positioned to avoid the risk of a
passenger train stopping in a hazardous location (eg on a viaduct or in a tunnel).
B6.5.2
Where a signal is required at such a location, eg so as to maintain headway,
signalling controls shall be applied to the previous signal so as to minimise the
risk of a train being brought to a stand at such a location. Where two or more
successive signal sections are affected by such controls, the headway is likely to
be adversely affected.
B6.5.3
It is not necessary to apply such special controls where the risks associated with
trains stopping on viaducts or in tunnels are adequately controlled by other
means, such as:
Hazard
Control measure
Passengers alighting (other
than at a station)
Central door locking or power operated doors on
all trains; trackside walkways for train evacuation
purposes.
Drivers able to pass signals at
danger on own authority
Secure communication between all trains and
the controlling signal centre.
SPAD
Train protection system fitted to trains and to
signals that control movements up to signals at
the hazardous location.
Table 1
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B6.5.4
Where practicable, stop signals shall be positioned such that the driver is not
exposed to hazards such as live d.c. traction rails when leaving the cab of a train
stopped at the signal.
Stop signals shall be positioned so that the exposure of the driver to hazard whilst
using the signal post telephone is minimised.
B6.6 Other constraints
Subject to all other requirements for the positioning of signals having been met,
stop signals shall, where practicable, be positioned such that trains are not
required to stop:
a)
on severe rising or falling gradients
b)
at known sites of poor adhesion.
B6.7 Movements onto occupied running lines
GK/RT0044 specifies limits on the distance from the protecting signal to the rear
of a train ahead where a movement onto an occupied running line is to be
permitted.
B6.8 Overhead electrification systems (25kV a.c. and 1.5kV d.c.)
B6.8.1
On lines electrified with overhead systems, stop signals shall be appropriately
positioned in relation to a neutral section or section gap to minimise the likelihood
of:
a)
an electric train with only one pantograph being brought to rest with the
pantograph in a neutral section or section gap
b)
an electric train restarting from a signal stalling in a neutral section or
section gap (allowance being made for the gradient, the attainable speed
and the positions of the APC magnets, where provided).
B6.8.2
Stop signals shall be appropriately positioned in relation to relevant overhead line
sectioning locations, so as to minimise the likelihood of an electric arc being
drawn when a pantograph bridges the sectioning point when the train is travelling
slowly or is stationary.
B6.8.3
To ensure that the requirements of sections B6.8.1 and B6.8.2 are met,
consideration shall be given to the positions of the pantographs on all types and
formations of stock which are authorised to operate on the route.
B6.9 Conductor rail electrification systems
B6.9.1
On lines electrified with conductor rail systems, stop signals shall be positioned to
minimise the likelihood of trains stalling in conductor rail gaps.
B6.9.2
Where there is a gap between two sections of conductor rail which can be
electrically isolated from each other by remote switching, stop signals shall be
positioned to ensure that it is not possible for a train stopped at a signal to bridge
the gap.
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Provision of Lineside Signals
B7 Designation of main
signals
B7.1 Designation of main signals
Main signals shall be designated as ‘Passable’ or ‘Non-passable’ for the purpose
of specifying whether or not a driver is permitted to pass the signal at danger
under his own authority.
The requirements for the provision of identification plates to indicate the
designation of signals are set out in section B12 of this document.
B7.2 Non-passable signals in track circuit block areas
B7.2.1
A main signal shall be designated as non-passable where a significant hazard
would arise from the driver passing a signal at danger under his own authority. A
significant hazard shall always be considered to exist in any of the following
situations:
a)
where the signal protects points within the route up to the signal ahead
b)
where the layout is such that a directly opposing route or overlap could
conflict with the route or overlap
c)
where the signal protects other hazardous features of the permanent way
(eg a moveable bridge)
d)
where the signal protects a manually controlled level crossing
e)
where the signal is required to be held at red on the approach to a traction
supply section that is isolated.
B7.2.2
In addition to the circumstances listed in the above section, where operational
circumstances exist which make it undesirable for the driver of a train to be
allowed to pass a signal at danger under his own authority, the signal shall be
designated as non-passable, although it is permissible for the interlocking system
to treat it as automatic.
B7.3 Passable signals in track circuit block areas
B7.3.1
It is permissible for a main signal to be designated as Passable where none of
the significant hazards listed in section B7.2 exists.
B7.3.2
Where the overlap beyond the signal ahead of the signal under consideration
contains points or a level crossing but there is no other hazard (as listed in
section B7.2), it is permissible, subject to a risk assessment, for the signal under
consideration to be designated as passable; although the interlocking system has
to treat it as controlled (see GK/RT0060). The risk assessment shall include, but
not be limited to, consideration of the following:
a)
the distance of the points or level crossing beyond the signal ahead
b)
the frequency and nature of conflicting movements
c)
the likelihood and consequences of the signal ahead being passed at
danger.
B7.4 Intermediate block home signals in absolute block areas
A main stop signal shall be designated an intermediate block home signal where
it is provided to enable an additional block section to be controlled by one signal
box (under the Absolute Block Regulations) and where none of the significant
hazards listed in section B7.2 exists.
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B7.5 Stop signals in other than track circuit block areas
All main stop signals shall be classified as controlled and non-passable, with the
exception of those designated as intermediate block home signals.
B8 Aspect sequences
B8.1 Standard three aspect sequence
B8.1.1
A driver, running under authority of a green aspect in a three aspect section of line,
shall be warned of a stop aspect by the standard three aspect sequence. The
minimum signal spacing distances between the yellow and red aspects for various
speeds and gradients are set out in GK/RT0034.
B8.1.2
Where the headway requirements are such that that the distance between
successive stop signals is greater than the maximum allowed by GK/RT0034,
separate distant signals shall be provided.
B8.1.3
Where the permissible speed of trains is greater than 100 mph, four aspect signalling
shall be considered (for areas where three aspect signalling would otherwise be
adequate), due to the long signal spacing distances which would be encountered by
slower speed trains.
In deciding whether to apply four aspect signalling, the following factors shall be
considered:
a)
range of permissible speeds of trains authorised to use the route
b)
range of permissible braking characteristics of trains authorised to use the
route
c)
infrastructure improvements allowing future increase in permissible speed
d)
anticipated incidence of poor visibility (mist, fog, etc)
e)
variation in signal spacing distance due to gradient changes
f)
variation in required reading time of successive signals (for whatever
reason)
g)
risks associated with isolated sections of four aspect signalling along a
predominantly three aspect route.
B8.2 Modified three aspect sequence
Where it is necessary to position signals such that the required spacing between a
yellow and a red aspect in the standard three aspect sequence cannot be provided,
sufficient warning of the stop aspect shall be provided by means of one of the
following:
a)
an isolated standard four aspect sequence (preferred method)
b)
approach control from red of the previous signal to the signal with sub-standard
spacing. The approach control shall be such as to ensure that the speed of the
train is reduced to an extent commensurate with the reduced signal spacing to
the signal ahead.
The modified aspect sequence is then:
Green – Single Yellow – Red/controlled to Single Yellow – Red
c)
RAILWAY SAFETY
the imposition of a speed restriction.
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Provision of Lineside Signals
B8.3 Standard four aspect sequence
A driver, running under authority of a green aspect on a four aspect section of line,
shall be warned of a stop aspect by the standard four aspect sequence. The
minimum signal spacing distances between the double yellow and red aspects for
various speeds and gradients are set out in GK/RT0034.
B8.4 Modified four aspect sequences
B8.4.1
Where it is necessary to position signals such that the required spacing cannot be
provided between a double yellow and a red aspect in the standard four aspect
sequence, double yellow aspects shall be additionally displayed at one or more
preceding signals such that minimum signal spacing distance is provided between
the outermost double yellow aspect and the red aspect. The standard aspect
sequence is therefore modified:
Green – Double Yellow - Double Yellow – Single Yellow (*) – Red
Such sequences shall be avoided unless the required headway and signal
spacing cannot be achieved by any other means. Additional mitigation shall be
provided by a train protection system, fitted as a minimum to the signal marked
thus (*) in the diagram above. This system shall be configured to stop
movements within the overlap beyond the signal marked when it is displaying a
red aspect.
As an alternative to a modified aspect sequence it is permissible, where
appropriate, to impose a restriction of the permissible speed (differential if
necessary) to enable the required signal spacing distance to be accommodated
within a standard aspect sequence.
B8.4.2
Where it is necessary to position signals such that the spacing between the single
yellow and the red aspect does not meet the requirements of GK/RT0034 for a four
aspect sequence (ie one third of the applicable signal spacing distance), then one of
the following modified aspect sequences shall be adopted:
a)
The previous signal to the signal at danger shall be approach controlled
from red. The approach control shall be such as to ensure that the speed of
the train is reduced to an extent commensurate with the reduced signal
spacing to the signal ahead. The modified aspect sequence is then:
Green – Double Yellow - Single Yellow – Red/controlled to Single Yellow – Red
b)
The previous signal to the signal at danger shall display a single yellow
aspect and the signal previous to that signal shall also display a single yellow
aspect. This modified aspect sequence shall be applied only where the
previous signal to the signal at danger is a closing up or a mid-platform
signal. Additional mitigation shall be provided by a train protection system,
fitted as a minimum to the signal marked thus (*) in the diagram below. This
system shall be configured to stop movements within the overlap beyond the
signal marked when it is displaying a red aspect.
The sequence is then:
Green – Double Yellow - Single Yellow – Single Yellow (*) – Red
Any such sequence shall not include more than two consecutive single yellow
aspects.
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B8.4.3
Where, in a modified four aspect sequence, it is necessary that a particular signal
never displays a double yellow aspect, that signal shall retain the form of a four
aspect head.
B8.4.4
Where, in a modified four 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 ahead of the junction on the diverging route to enable a train
traversing the junction at the permissible speed for the diverging route to stop at it.
B8.5 Semaphore aspect sequences leading to a stop aspect
B8.5.1
Under normal operating circumstances, the minimum warning of a semaphore signal
at danger shall be a distant signal caution aspect displayed at least minimum signal
spacing distance from the stop signal.
B8.5.2
Where a signal ahead of the first stop signal beyond the distant signal is being held at
danger, the preceding stop signal shall also be maintained at danger (preferably by
signalling controls but alternatively by instruction) until such time as an approaching
train is nearly at a stand.
B8.5.3
A distant signal shall display a clear aspect only when all the stop signals to which it
applies are displaying a clear aspect.
B8.5.4
The distant signal shall be capable of displaying caution and clear aspects unless it
applies to a place where either:
a)
all trains stop, or
b)
a very low permissible speed applies (typically 20 mph or less).
In these cases it is permissible for it to be fixed at caution or a distant board provided.
B8.5.5
Where the next signal ahead of a distant signal is a stop signal to which the distant
signal does not apply, a repeat distant arm shall be provided in association with that
stop signal.
B8.6 Semaphore equivalent aspect sequence
Where semaphore signals are replaced by colour light signals and signal spacing in
accordance with GK/RT0034 is possible, standard three or four aspect sequences
shall be provided.
Where, however, constraints on signal spacing prevent the use of the normal colour
light aspect sequences, the aspect sequence principles for semaphore signalling
shall be followed, as described in section B8.5. All colour light stop signals (other
than the section signal) shall be capable of displaying a yellow aspect, and each stop
signal shall display a green aspect only when all stop signals ahead, up to and
including the section signal, display green aspects.
B8.7 Aspect sequence where no main route reads up to a signal
It is permissible for a signal which cannot be approached under the authority of a
main aspect (eg a terminal platform starting or yard exit signal) to show a red aspect
with no preceding warning signal.
RAILWAY SAFETY
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Provision of Lineside Signals
The following sequence shall be displayed when such a starting signal is displaying a
proceed aspect with the next signal ahead at danger:
Single Yellow – Red
When the starting signal is off while the second signal beyond the starting signal is at
danger, the following sequence shall be displayed, except in the circumstances
described below:
Green – Single Yellow – Red
This sequence shall not be displayed where the yellow aspect of the signal
immediately beyond the starting signal would alone provide insufficient signal spacing
distance to the red aspect in accordance with GK/RT0034, having regard to
attainable speed. In such circumstances the starting signal shall display a double
yellow aspect.
B8.8 Aspect sequence up to a points indicator
A points indicator shall be preceded by a signal (at the appropriate signal spacing
distance) displaying a caution aspect, except where all trains start from rest within
sight of the indicator. It is permissible for the caution aspect to take the form of a
colour light yellow aspect, a semaphore distant signal arm fixed in the caution
position, or a distant board.
B8.9 Aspect sequence up to a stop board
A stop board shall be preceded by a signal displaying a caution aspect, except where
it cannot be approached by a running movement. It is permissible for such a signal to
take the form of a colour light yellow aspect, a semaphore distant arm fixed in the
caution position or a distant board, positioned at the appropriate signal spacing
distance.
B8.10 Aspect sequence up to a buffer stop
A buffer stop shall be regarded as a stop aspect for the purposes of aspect
sequences and the cautionary aspect, or aspect sequence, appropriate to the
prevailing type of signalling (ie colour light or semaphore) shall be displayed at signal
spacing distance on the approach. It is permissible for a distant board to be provided.
B8.11 Stepping down of aspect
In track circuit block areas, where technically feasible, failure of illumination of a
proceed aspect of a colour light signal shall cause the display of a more restrictive
aspect in that signal, with the aspects in the previous signal(s) adjusted to preserve a
correct sequence.
Failure of illumination of the most restrictive aspect shall cause the previous stop
signal to display a red aspect.
B8.12 Prohibited aspect sequences
Successive signals shall not simultaneously display the following:
16
a)
a red aspect immediately preceded by any colour light aspect other than a
single yellow aspect
b)
a single yellow aspect followed by any aspect other than red, except as
permitted in sections B8.4.2b and B8.6
c)
a red aspect immediately preceded by a semaphore distant arm in the ‘off’
position
d)
a semaphore stop signal arm in the ‘on’ position preceded by a semaphore
distant signal arm in the ‘off’ position
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e)
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Date February 2002
Page 17 of 36
a semaphore stop signal arm in the ‘on’ position preceded by any colour
light aspect other than a single yellow aspect.
B9 Aspect sequence
transitions
B9.1 Segregation of three and four aspect sequences
B9.1.1
The number of transitions between three and four aspect signalling shall be kept to a
minimum. However, where signal spacing and headway considerations require such
boundaries, each group of three or four aspect signals shall consist of a sufficient
number of signals (typically three complete sequences) to establish a clear pattern for
the driver (except as permitted by section B9.1.2).
B9.1.2
It is permissible for an isolated four aspect sequence to be displayed in an otherwise
three aspect sequence (see section B8.2), but an isolated three aspect sequence
shall not be displayed in a four aspect section of line, except in respect of a signal
which has no main signal route reading up to it, as detailed in section B8.7 of this
document.
B9.1.3
It is permissible for parallel running lines signalled for movements in the same
direction to be considered as independent sections of line for the purpose of this
section B9.
B9.2 Transition from three aspect to four aspect
At the transition from continuous three to four aspect signalling, one of the following
arrangements shall be applied (see diagrams in Appendix 1):
a)
The first four aspect signal displays a single yellow up to the next signal at
red or a double yellow up to the next but one signal at red. A train protection
system shall be provided at (as a minimum) the last signal in the three
aspect sequence (signal 7 in Appendix 1 Figure A1.1).
b)
The first four aspect signal shows only red/double yellow/green and an
additional distant signal (yellow/double yellow/green) is provided between it
and the next stop signal ahead.
b)
The first four aspect signal is approach controlled from red to yellow when the
next signal ahead is at red.
In deciding which method to apply, the following factors shall be considered:
RAILWAY SAFETY
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Provision of Lineside Signals
Method
a) First caution for
two consecutive
signals
Factors
a) The relative likelihood of a driver seeing the first 4aspect signal (signal 5 in Appendix 1, Figure A1.1) at
single yellow and double yellow respectively.
b) The likelihood of a driver mis-reading a single yellow
aspect at signal 5 as double yellow (because he
usually receives a double yellow).
The distance from the double yellow to the red (signal 9 in
Appendix 1, Figure A1.1) will generally be greater than the
signal spacing distance by at least 50%, so that a risk
assessment in accordance with GK/RT0034 will be
necessary.
b) Additional distant
signal
The practicability of fitting in an isolated distant signal in
respect of:
a) distance to facing points, level crossings
b) the effect on signals on parallel lines
c) adequacy of overlaps and standage
d) position of critical electric traction sectioning points
c) Approach control
a) the effect of approach control from red on driver
anticipation.
b) secondary hazards created by loss of headway and
consequent increase in incidence of red signals seen
by drivers.
Table 2
A further factor for consideration is need for consistency, ie the undesirability of
mixing methods a) and b) in successive transitions.
B9.3 Transition from four aspect to three aspect
At the transition from four to three aspect signalling, the first signal in the three aspect
sequence (ie which shows a single yellow aspect when the preceding signal is at
green) shall not have the appearance of a four aspect head. This prohibition is not
applicable where the transition occurs at a junction signal in respect of a branch or
slow line.
If the first signal beyond the junction on the branch or slow line is at least minimum
signal spacing distance from the next signal beyond, the junction signal shall display
a green aspect when this next signal is at single yellow.
B9.4 Transition from colour light to semaphore
At the transition from colour light to semaphore signalling, it is permissible for the last
colour light signal to be one of the following:
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a)
a colour light distant signal
b)
a three aspect stop signal at the correct signal spacing distance (ie also
performing the function of the distant for the semaphore stop signal ahead)
c)
a stop signal capable of showing single yellow at less than signal spacing
distance (but at least one-third of signal spacing distance – see GK/RT0034)
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from the semaphore stop signal ahead, preceded by a signal capable of
showing double yellow, which is located at not less than minimum signal
spacing distance from the semaphore stop signal
d)
a red/green stop signal.
B9.5 Transition from semaphore to colour light
At the transition from semaphore to colour light signalling, it is permissible for the
distant signal preceding the first colour light stop signal to be either of the following:
a)
colour light
b)
power worked semaphore.
It is not permissible for the last semaphore stop signal to have a colour light lower
distant on the same post.
B9.6 Interfaces with other signalling systems
Within the transition zone between different types of lineside signalling systems,
all route indications and signal aspects shall be displayed so as to permit the
driver to comply with subsequent signals, including route indications, and
subsequent changes in permissible speed over the route set. A specific example
of such arrangements is given in Appendix 2.
The core requirements for transitions between lineside and cab signalling
systems are set out in GE/RT8026.
B10 Junction signalling
B10.1 Method of junction control
In order to enable a driver to control the train speed correctly through a diverging
junction, an appropriate combination of aspect sequences and approach control
shall be applied. The permitted combinations for colour light signalling and the
criteria for their use are set out in Appendix 3.
The requirements for the signing of permissible speeds over a junction are set
out in GK/RT0038.
B10.2 Indication of route
B10.2.1
The route set at a colour light junction signal shall be indicated to the driver by
means of one of the following:
a)
a position light junction indicator
b)
an alphanumeric route Indicator
c)
a combination of a position light junction indicator (to define routing) and an
alphanumeric route indicator (to define destination); see section B10.3c).
Subject to approach speed and sighting requirements, position light junction
indicators shall be provided for simple junctions, and standard alphanumeric
route indicators for complex junctions (eg at the approaches to major stations).
GK/RT0031 sets out constraints on:
RAILWAY SAFETY
a)
the use of standard alphanumeric route indicators
b)
the particular route indications permitted to be displayed, for both position
light junction indicators and for alphanumeric route indicators.
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Provision of Lineside Signals
B10.2.2
Where it is self-evident that the main or highest speed route lies straight ahead,
then no indication shall be given for that route unless this is required to facilitate
consistency of route indications as required by GK/RT0037.
Where there is no route ahead of a junction signal which is self evidently the main
or highest speed route, a route indication shall be provided for all signalled
routes.
Where the track layout is such that the straightest route through the junction is an
unsignalled route, but which might appear to a train driver to be a legitimate
route, a route indication shall be provided for all signalled routes.
Where routes from a signal with position light junction indicators diverge but then
cross on the level before reaching the signal ahead, the junction indicator
positions shall reflect the order in which the divergences from the straight route
occur, rather than the geographical positions of the signals ahead.
B10.3 Alternative routes to a common destination
One of the following arrangements shall be applied to a signal that has more than
one route to a common destination:
a)
The same route indication shall be displayed for all routes. Any route
having a permissible speed of more than 10 mph lower than the highest
speed applicable to that destination shall be approach controlled to an
extent commensurate with the lower permissible speed. The same route
indication shall not be given for alternative routes with a speed differential of
more than 10 mph.
b)
The routing and destination shall be displayed by different indications of the
route indicator or position light junction indicator (see section B10.2.1).
c)
Exceptionally, where the complexity of the layout warrants, the routing and
destination shall be displayed by a combination of route indicators, the
routing by a position light junction indicator and the destination by an
alphanumeric route indicator.
B10.4 Unrestricted aspect sequence
Where an unrestricted aspect sequence is applied to a diverging route, both the
junction signal and the preceding signals shall be free to display aspects as
determined by the aspects beyond the junction for the route set.
B10.5 Approach control from yellow (free yellow)
B10.5.1
Where approach control from yellow is applied to the junction signal, it shall clear
from yellow to a less restrictive aspect (as determined by the aspect displayed at
the signal ahead) when the approaching train has passed the double yellow and
reached a position from which the route indication and main signal are both
readable (see GK/RT0031 Issue 4, Table 16). Wherever possible, this shall be
before reaching the associated AWS inductor.
B10.5.2
Where there is a significant risk of reading through from the junction signal to the exit
signal of the route from the approach controlled signal, the latter shall be held at red
until such time as the junction signal is required to clear from yellow.
B10.6 Flashing yellow aspects
B10.6.1
In three aspect signalling a flashing single yellow aspect shall be displayed in the
following sequence:
Green – Flashing Single Yellow – Single Yellow (Junction Signal)
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In four aspect signalling flashing yellow aspects shall be displayed in the following
sequence:
Green – Flashing Double Yellow – Flashing Single Yellow – Single Yellow (Junction
Signal)
The sequences defined above shall not be extended by displaying flashing aspects at
a greater number of signals than shown. No signal shall be capable of displaying
flashing aspects relating to more than one junction signal.
B10.6.2
The positioning of junction signals shall, if possible, be such that the driver of an
approaching train can read the route indicator at the same time as the main
aspects. However, if this is not possible, then:
a)
the junction signal shall be maintained at red if the approaching train has
reached a position corresponding to less than the required reading time on
the approach to the signal which would display flashing single yellow, and
b)
the junction signal shall be placed and maintained at red if the signal that
should display flashing single yellow fails to commence flashing or
subsequently fails.
In both of the above cases, the junction signal shall subsequently be approach
controlled from red.
B10.6.3
The junction signal shall clear from yellow to a higher aspect (as determined by
the aspect displayed at the signal ahead) when the approaching train has passed
the flashing single yellow and reached a position from which the route indication
and main signal are both readable. Wherever possible, this shall be before
reaching the associated AWS inductor (see GK/RT0031 Issue 4, Table 16).
B10.6.4
Where there is a significant risk of reading through from the junction signal to the exit
signal of the route from the approach controlled signal, the latter shall be held at red
until such time as the junction signal is required to clear from yellow.
B10.6.5
A flashing yellow aspect sequence shall be inhibited when the signal ahead of the
junction on the diverging route is at red, unless one of the following conditions
applies:
a)
The controls for the signal ahead are satisfied (except approach control)
and the signal is therefore capable of clearing to a proceed aspect once any
approach control conditions have been satisfied.
b)
The signal ahead is at the end of a loop or station platform line where the
drivers of all trains expect to stop.
B10.7 Colour light splitting distant aspects
B10.7.1
Where advance warning of a diverging route is conveyed by an aspect sequence
employing splitting distant aspects, the junction signal shall be free to display aspects
as determined by the aspect of the signal ahead. The signal immediately preceding
RAILWAY SAFETY
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Provision of Lineside Signals
the junction signal shall display the splitting distant aspect appropriate to the aspect
displayed by the junction signal.
See Appendix 4 for the aspects displayed in the main and offset heads and for
aspect sequences approaching junctions controlled by splitting distant signals.
See GE/RT8035 for the AWS indications to be given at colour light splitting
distant signals.
B10.7.2
An outer splitting distant signal shall be provided only where a splitting distant alone
cannot be positioned so as to give sufficient advance warning of a divergence for
either of the following purposes:
a)
to enable the necessary reduction of speed to meet the permissible speed
over or beyond a turnout
b)
to enable a driver whose train which is being misrouted to stop before reaching
the junction signal, where the misrouting of trains would give rise to a safety
hazard (eg gauge or traction system incompatibility or serious operational
inconvenience).
Where an outer splitting distant is provided, the signal preceding the junction signal
becomes an inner splitting distant signal. However, the use of an outer splitting
distant shall be avoided wherever possible, eg by positioning the splitting distant at an
appropriate distance from the junction signal (within the constraints set out in
GK/RT0034).
B10.7.3
The positioning of junction signals shall, if possible, be such that the driver of an
approaching train can read the route indicator at the same time as the main
aspects. However, if this is not possible, then:
a)
the junction signal shall be maintained at red if the approaching train has
reached a position less than the required reading time on the approach to
the signal which would display the inner splitting distant indication, and
b)
the junction signal shall be placed and maintained at red if the signal that
should display the inner splitting distant indication fails to do so or
subsequently fails.
In both of the above cases, the junction signal shall subsequently be approach
controlled from red.
B10.7.4
Splitting distant aspect sequences are not permitted to extend back to another
junction signal if the sequence would apply to any route other than the main
(highest speed) route at that junction signal.
B10.8 Approach control from red
B10.8.1
Where approach control from red is applied to the junction signal, the approach
aspect sequence shall be identical to the sequence displayed when the signal is
at danger for any other reason.
B10.8.2
The junction signal shall clear from red to a higher aspect (as determined by the
aspect displayed at the signal ahead) when the approaching train has passed the
single yellow and reached a position from which the route indication and main
signal are both readable – see GK/RT0031, Issue 4, Table 16. Wherever
possible, this shall be before reaching the associated AWS.
B10.8.3
Where a banner signal applies to the junction signal, either
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a)
splitting banners shall be provided, or
b)
the clearance of the junction signal for the approach controlled route shall be
delayed until the train has passed the banner.
B10.9 Provision for facilities for temporary approach control
Facilities shall be provided to enable temporary approach control from red to be
enforced in the event that it is necessary to impose a temporary or emergency
speed restriction through or beyond junctions on a route signalled by any of the
following:
a)
an unrestricted aspect sequence (see section B10.4)
b)
a free yellow aspect sequence (see section B10.5)
c)
a flashing yellow aspect sequence which is applicable to more than one
route (see Appendix 1).
B10.10 Semaphore aspect sequences for junctions
B10.10.1
The route set at a semaphore junction signal shall be indicated to the driver by
means of multiple semaphore arms, displayed in accordance with the principles
defined in GK/RT0031 and GK/RT0037, and/or by an alphanumeric route indicator in
association with a single semaphore arm.
B10.10.2
A semaphore distant signal shall not be capable of being cleared for a diverging
route, except where it forms part of a splitting distant signal.
B10.10.3
It is permissible to provide semaphore splitting distant signals where the use of a
single distant arm would be too restrictive to enable trains to take the diverging route
at the permissible speed (taking into account also the permissible speed beyond the
junction on the diverging route).
B10.10.4
Where a semaphore splitting distant signal is provided, the appropriate distant signal
arm shall be off only when the corresponding junction signal arm, and any other stop
signals to which the distant arm applies, are also off. Where a semaphore stop signal
on the approach to a junction signal conveys an indication of the route to be taken at
the junction, the driver shall be given equivalent route information at any preceding
stop signals controlled from the same signal box.
See GE/RT8035 for the AWS indication to be given at a semaphore splitting distant
signal.
B10.10.5
Where the next signal ahead of a splitting distant signal is a stop signal to which the
splitting distant signal does not apply, repeat splitting distant arms shall be provided in
association with that stop signal (see section B8.5.5).
B10.11 Route indicators for position light signals
The requirements for the application of route indicators to position light signals are set
out in GK/RT0031 (Lineside Signals and Indicators).
B10.12 Prohibited aspect sequences at junctions
The following combinations are prohibited:
a)
RAILWAY SAFETY
a flashing single yellow aspect immediately preceded by a signal displaying
a flashing single yellow aspect
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Provision of Lineside Signals
b)
a flashing double yellow aspect immediately preceded by a signal displaying
a flashing single yellow aspect or flashing double yellow aspect
c)
a flashing double yellow aspect immediately followed by a signal displaying
any aspect other than flashing single yellow
d)
any sequence involving both a flashing colour light aspect and a semaphore
signal
e)
a free yellow aspect sequence and a flashing yellow sequence for different
routes from the same junction signal
f)
flashing aspects relating to more than one junction signal
g)
a flashing aspect and a splitting distant aspect sequence for different routes
from the same junction signal.
B11 Bi-directional
signalling
This section does not apply to adjacent lines signalled as independent single
lines by one of the means set out in GK/RT0051.
All other requirements of this document apply to signals for both directions on bidirectional lines.
Two forms of bi-directional signalling are permitted, as set out below:
B11.1 Full bi-directional signalling
B11.1.1
For every signal provided, there shall be a parallel signal for movements in the
same direction on the adjacent line(s). GK/RT0037 specifies other requirements
for the positioning of parallel signals.
B11.1.2
On bi-directional lines where a predominant (normal) direction of traffic is
designated, it is permissible for signalling in the contra-flow direction to be three
aspect whilst that in the same (normal) direction on the adjacent line is four
aspect, provided that a lower permissible speed is applied for contra-flow
direction movements, to correspond with the reduced signal spacing distance
between the caution aspect and the stop signal.
B11.2 Reduced capacity bi-directional signalling
B11.2.1
Where the headway requirement for the contra-flow direction does not warrant
the same signal spacing as is provided for the normal direction, it is permissible
to provide fewer signals, but consecutive stop signals shall not be more than ten
miles apart.
Where provided, contra-flow direction signals shall be positioned parallel to
normal direction signals on the adjacent line(s), subject to signal sighting
requirements.
B11.2.2
It is permitted for the provisions of section B11.1.2 to be applied.
B12 Identity of signals
B12.1 Signal numbering
B12.1.1
Each signal shall have an identity that is unique to its controlling signal box or
locality, comprising the signal box prefixes code, the signal number and, where
required, a suffix (see section B12.1.3).
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GK/RT0032
Issue Two
Date February 2002
Page 25 of 36
The number of each signal worked by a lever shall be the same as the lever
number.
All signals, including automatic and distant signals, except distant signals worked
from the same lever as a stop signal, (see section B12.1.3) shall be individually
numbered as part of a sequence. Separate sequences shall be used for:
a)
running signals (including slots) and equivalent stop or distant boards
b)
shunting signals (including slots), limit of shunt signals and equivalent stop
boards.
B12.1.2
Except where signals are worked by levers, the rules for determining the
sequences of numbers are as follows:
a)
The sequences of numbers shall be separate and distinct from other
numbered functions such as points, ground frame releases and lockout
systems.
b)
The sequences shall be logical and the rationale for the numbering shall be
documented as part of the signalling design records.
c)
Odd numbers shall be used for down direction signals and even numbers for
up direction signals.
d)
Odd numbers shall usually ascend and even numbers descend in the
direction of traffic flow.
e)
It is permissible to vary the numbering sequence to achieve a logical
arrangement, eg to give platform-starting signals at a terminal station the
same numbers as their platforms.
f)
If there is more than one running line in each direction (eg fast and slow) the
numbers for each line shall be in separate sequences.
g)
As far as possible, train drivers shall be presented at successive signals
with signal numbers which are consecutive odd or even numbers.
h)
Where up to five signals applying to traffic in the same direction are
positioned side by side the last digit of each signal identity shall be different.
i)
Where more than five signals are positioned side by side, the last digit of the
identities of adjacent signals shall be different.
Exceptions to the above are permitted to achieve consistency with existing
numbering sequences.
B12.1.3
The following signal suffixes shall be used for the applications indicated and not
for any other purpose:
BR – for a banner repeating signal, the number being the same as that of the
repeated signal.
CA – for a co-acting signal, the number being the same as that of the primary
signal.
R – solely for a distant signal worked from the same operating device as a stop
signal, the number being that of the stop signal.
RR – solely for an outer distant signal worked from the same operating device as
a stop signal, the number being that of the stop signal.
RAILWAY SAFETY
25
Document to be Withdrawn as of 03/04/2010
To be Superseded by GKRT0045 Iss 1 Published on 06/02/2010
Uncontrolled When Printed
Railway Group Standard
GK/RT0032
Issue Two
Date February 2002
Page 26 of 36
Provision of Lineside Signals
B12.2 Signal identification plates
B12.2.1
Identification plates as depicted in GK/RT0033 shall be provided at the following
signals:
a)
Colour light signals.
b)
Semaphore running signals.
c)
Position light shunt and limit of shunt signals.
d)
Banner repeater signals.
e)
Stop boards.
f)
Distant boards.
Identification plates are not required at other types of signal or board.
B12.2.2
In addition, the following signals require the appropriate sign, which shall be
combined with the identification plate (see GK/RT0033):
a)
Passable signals (auto plate).
b)
Intermediate block home signals.
c)
Colour light distant signals.
B12.2.3
Identification plates at main signals shall display the signal box prefix code, the
signal number and a suffix where required. For shunt signals, it is permissible to
omit the signal box code.
B12.2.4
Identification plates shall indicate, by means of an arrow, the line to which the
signal applies where the signal is positioned on the right hand side of the line in
the direction of traffic flow. It is permissible to provide an arrow for signals on the
left hand side, where this helps to avoid confusion.
26
RAILWAY SAFETY
Document to be Withdrawn as of 03/04/2010
To be Superseded by GKRT0045 Iss 1 Published on 06/02/2010
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Provision of Lineside Signals
Railway Group Standard
GK/RT0032
Issue Two
Date February 2002
Page 27 of 36
Appendix 1
(This Appendix is mandatory)
Transition from Three to Four Aspect Signalling
1
3
5
3asp
3asp
4asp
G
7*
9
4asp
11
4asp
13
4asp
4asp
Y
R
G
Y
R
YY
Y
R
G
YY
Y
R
G
YY
Y
R
G
YY
Y
G
YY
G
* Train protection system (eg TPWS) required at this signal (No. 7)
Figure A1.1 Signal 3 providing first caution for both signal 7 and signal 9 (Section B9.2 a)
G
1
3
5
3asp
3asp
4asp
7
9
3asp YGY
11
4asp
13
4asp
4asp
Y
R
G
YY
Y
R
G
YY
Y
R
G
YY
Y
R
G
YY
Y
G
YY
G
Figure A1.2 Additional distant signal 7 provided (Section B9.2 b)
RAILWAY SAFETY
27
Document to be Withdrawn as of 03/04/2010
To be Superseded by GKRT0045 Iss 1 Published on 06/02/2010
Uncontrolled When Printed
Railway Group Standard
GK/RT0032
Issue Two
Date February 2002
Page 28 of 36
Provision of Lineside Signals
Transition from Three to Four Aspect Signalling
G
1
3
5
7
9
3asp
3asp
3asp
4asp
4asp
Y
R
G
Y
11
13
4asp
4asp
#1
G
R
Y
R
YY
Y
R
G
YY
Y
R
G
YY
Y
G
YY
#1: approach control condition
Figure A1.3 Signal 7 approach controlled from red when signal 9 at red (Section B9.2 c)
28
RAILWAY SAFETY
Document to be Withdrawn as of 03/04/2010
To be Superseded by GKRT0045 Iss 1 Published on 06/02/2010
Uncontrolled When Printed
Provision of Lineside Signals
Railway Group Standard
GK/RT0032
Issue Two
Date February 2002
Page 29 of 36
Appendix 2
(This Appendix is for information)
Interface with London Underground lineside
signalling
This Appendix details the historical interface arrangements between Railtrack and
LUL infrastructure. LUL use a two aspect (red/green) signalling system. A green
aspect permits trains to travel at permissible speed until sighting a red aspect.
Where sighting distances are less than train stopping distances, repeater signals
(yellow/green) are provided. An exception applies on lines traversed by non-LUL
trains, where aspect sequences complying with this document are provided.
The following examples apply to interfaces that are traversed only by LUL trains.
Where non-LUL trains cross the interface, aspect sequences and signal spacing
distances that comply with Railway Group standards are provided.
When travelling on Railtrack controlled infrastructure, the aspect sequences
mandated in this document also apply to LUL trains.
i) Railtrack to LUL
The last Railtrack signal is a stop signal.
Where the first LUL stop signal is at greater than train stopping distance from the
last stop signal on Railtrack controlled infrastructure, the latter is a two aspect
(red/green) stop signal.
An exception occurs where the first LUL stop signal would otherwise have
required a yellow/green repeating signal visible to the driver of a train standing at
the last Railtrack controlled stop signal. In such circumstances, the yellow/green
repeating signal is omitted, but the last Railtrack controlled signal is capable of
displaying a yellow aspect to provide an aspect sequence complying with this
document.
Where the first LUL stop signal is at less than train stopping distance from the
last Railtrack controlled stop signal, an aspect sequence complying with this
document is provided up to the first LUL stop signal.
ii) LUL to Railtrack
The aspect sequence to the first stop signal on Railtrack controlled infrastructure
maintains the minimum signal spacing distance from the first caution to the stop
signal. Where necessary, a repeating signal associated with the last LUL stop
signal is provided to achieve such an aspect sequence.
RAILWAY SAFETY
29
Document to be Withdrawn as of 03/04/2010
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Uncontrolled When Printed
Railway Group Standard
GK/RT0032
Issue Two
Date February 2002
Page 30 of 36
Provision of Lineside Signals
Appendix 3
(This Appendix is mandatory)
Criteria for the selection of method of junction control (colour light
signalling)
In order to enable the driver to control the train speed correctly through a diverging junction, an appropriate
combination of aspect sequences and approach control has to be applied. The permitted forms of aspect sequences
and approach control are set out below, together with the criteria for their provision. In the table, the term ‘straightahead route’ refers to the higher speed route (for which a normal aspect sequence applies and no route indication or
approach control is provided), and the term ‘diverging route’ refers to the lower speed route (to which the permitted
forms of aspect sequence and approach control apply).
In selecting an appropriate form of junction control, consideration shall be given to the methods in the order listed,
cognisance being taken of the aspect sequences prohibited in sections B8.12 and B10.12.
Method of
control
Unrestricted
aspect
sequence
Criteria for use
(all criteria shall be met)
Section
reference
B10.4
a)
Not more than 10 mph difference between the permissible speeds of the
straight-ahead and diverging routes through and immediately beyond the
junction.
b)
No safety hazard would arise if the train is wrongly routed at the junction (eg
gauge or traction supply incompatibility; serious operational inconvenience with
consequential secondary safety hazards).
Notes:
i)
It is permissible to apply unrestricted aspect sequences to more than one
diverging route at a junction signal.
ii) It is permissible for the aspect of a junction signal to be unrestricted in
respect of trains approaching from a direction over which the permitted
speed is not greater than 10 mph more than the turnout speed, even
though approach control is required for the straight route approaching the
signal.
Free yellow
at junction
signal
30
a)
More than 10 mph difference between the permissible speeds of the straightahead and diverging routes through and immediately beyond the junction.
b)
The signal preceding the junction signal is able to show double yellow as part of
a four aspect sequence applicable to the diverging route.
c)
No safety hazard would arise if the train were wrongly routed at the junction (eg
gauge or traction supply incompatibility; serious operational inconvenience with
consequential secondary safety hazards).
d)
Approach control from red is too restrictive to enable trains to take the diverging
route at the permissible speed (taking into account also the permissible speed
beyond the junction on the diverging route).
e)
There is sufficient distance from the junction signal to the junction itself for the
driver to reduce speed to the permissible speed through and immediately
beyond the junction on the diverging route (taking into account the fact that a
double yellow aspect is displayed at the signal preceding the junction signal but
without any advance indication of which route is set at the junction).
f)
There is sufficient distance from the junction signal to the next stop signal on
both the straight-ahead and diverging route that a driver (having received a
double yellow at the signal preceding the junction signal but without any advance
indication of which route is set at the junction) can bring the train to a stand at
whichever stop signal beyond the junction he is routed to, even if he was
B10.5
RAILWAY SAFETY
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Provision of Lineside Signals
Method of
control
Railway Group Standard
GK/RT0032
Issue Two
Date February 2002
Page 31 of 36
Criteria for use
(all criteria shall be met)
Section
reference
expecting to be routed the other way.
Notes:
i)
It is permitted to apply free yellows 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.
ii) Sections e) and f) above are required to be met by all classes of train
authorised to run on the route.
Flashing
yellows
a)
It is not possible to apply either an unrestricted aspect sequence or a free yellow
at the junction.
b)
Approach control from red is too restrictive to enable trains to take the diverging
route at the permissible speed (taking into account also the permissible speed
beyond the junction on the diverging route).
Note:
Splitting
distants
B10.6
It is permitted to apply flashing yellows 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, and any safety hazards or serious operational
inconvenience arising from misrouting are common to all routes to which the
flashing yellow aspects apply.
a)
It is not possible to apply either an unrestricted aspect sequence or a free yellow
at the junction (see note 1).
b)
The use of a flashing yellow sequence or approach control from red is too
restrictive to enable trains to take the diverging route at the permissible speed
(taking into account also the permissible speed beyond the junction on the
diverging route).
Notes:
i)
B10.7
It is permitted to use a splitting distant aspect sequence where a safety
hazard or serious operational inconvenience precludes the use of an
unrestricted or free yellow aspect sequence.
ii) Only one offset head shall be provided on a splitting distant signal.
Approach
control from
red
Approach control from red shall be applied to:
a)
all diverging routes where the criteria for less restrictive aspect sequences (as
listed above) cannot be met
b)
other diverging routes at a junction that is equipped with splitting distants for one
of its diverging routes
c)
other diverging routes at a junction that is equipped with flashing aspects, but to
which the flashing aspect sequences do not apply
d)
other diverging routes at a junction that is equipped with a free yellow, but to
which the free yellow aspect sequence does not apply.
Note:
RAILWAY SAFETY
B10.8
There are also circumstances when a junction is equipped with flashing
yellows or splitting distants but it is not appropriate to use them, approach
control from red being applied instead. See sections B10.6.2, B10.6.5 and
B10.7.3.
31
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Uncontrolled When Printed
Railway Group Standard
GK/RT0032
Issue Two
Date February 2002
Page 32 of 36
Provision of Lineside Signals
Figure A3.1
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RAILWAY SAFETY
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Provision of Lineside Signals
Railway Group Standard
GK/RT0032
Issue Two
Date February 2002
Page 33 of 36
Appendix 4
(This Appendix is mandatory)
Colour light splitting distant signals: Permissible arrangement of aspects
Inner
Outer
Profile
Offset
Main
Meaning
Profile
Offset
Main
Meaning
Stop
Stop
Caution
Caution
Preliminary caution
(lower speed
divergence to left at
junction signal)
Preliminary caution
Preliminary caution
(straight-ahead route
set at junction signal)
Clear (lower speed
divergence to left at
junction signal)
Clear (lower speed
divergence to left at
junction signal)
Clear (straight-ahead
route set at junction
signal)
Clear (straight-ahead route
set at junction signal)
Figure A4.1 Splitting distant aspects for diverging route to left
RAILWAY SAFETY
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Document to be Withdrawn as of 03/04/2010
To be Superseded by GKRT0045 Iss 1 Published on 06/02/2010
Uncontrolled When Printed
Railway Group Standard
GK/RT0032
Issue Two
Date February 2002
Page 34 of 36
Provision of Lineside Signals
Colour light splitting distant signals: Permissible arrangement of aspects
Inner
Outer
Profile
Offset
Main
Meaning
Profile
Offset
Main
Meaning
Stop
Stop
Caution
Caution
Preliminary caution
(lower speed
divergence to right at
junction signal)
Preliminary caution
Preliminary caution
(straight-ahead route
set at junction signal)
Clear (lower speed
divergence to right at
junction signal)
Clear (lower speed
divergence to right at
junction signal)
Clear (straight-ahead
route set at junction
signal)
Clear (straight-ahead
route set at junction
signal)
Figure A4.2 Splitting distant aspects for diverging route to right
34
RAILWAY SAFETY
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To be Superseded by GKRT0045 Iss 1 Published on 06/02/2010
Uncontrolled When Printed
Provision of Lineside Signals
Railway Group Standard
GK/RT0032
Issue Two
Date February 2002
Page 35 of 36
Colour light splitting distant signals: Permissible aspect sequences
Left hand divergence; diverging route set
Left hand divergence; straight ahead route set
Right hand divergence; straight ahead route set
Right hand divergence; diverging route set
Figure A4.3 Colour light splitting distant signals: Permissible aspect sequences
Appendix 4 Legend
Lit Aspects:
Green
Yellow
Red
Unlit Aspect
Lit Position Light Junction Indicator
Unlit Position Light Junction Indicator
RAILWAY SAFETY
35
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Uncontrolled When Printed
Railway Group Standard
GK/RT0032
Issue Two
Date February 2002
Page 36 of 36
Provision of Lineside Signals
References
GA/RT6001
Railway Group Standards Change Procedures
GA/RT6004
Temporary Non-Compliance with Railway Group Standards
GA/RT6006
Derogations from Railway Group Standards
GE/RT8026
Safety Requirements for Cab Signalling Systems
GI/RT7012
Design, Construction and Maintenance of Level Crossings
(Due for publication in 2002)
GE/RT8035
GI/RT7006
Automatic Warning System (AWS)
Risk Assessment to Prevent & Mitigate Over-runs
GK/RT0002
Glossary of Signalling Terms
GK/RT0031
Lineside Signals and Indicators
GK/RT0033
Lineside Signs
GK/RT0034
Lineside Signal Spacing
GK/RT0037
Signal Positioning and Visibility
GK/RT0038
Signing of Permissible Speeds and Speed Restrictions
GK/RT0041
Track Circuit Block
GK/RT0042
Absolute Block
GK/RT0044
Controls for Signalling a Train onto an occupied Line
GK/RT0060
Interlocking Principles
GK/RT0051
Single Line Control
GK/RT0054
Radio Electronic Token Block
GK/RT0207
Signalling Design Production
GO/RT3000
Rule Book
The Catalogue of Railway Group Standards and the Railway Group Standards
CD-ROM give the current issue number and status of documents published by
Railway Safety.
36
RAILWAY SAFETY