Glossary of Railway Terminology-RSSB

Uncontrolled when printed
Superseded GERT8000-Gloss Iss 4 with effect from 01/12/2018
Glossary of Railway
Terminology
Issue 5
Glossary of Railway
Terminology
December 2018
Published by:
RSSB
The authoritative version of this document is available at
www.rssb.co.uk
Contents approved by Traffic Operations and Management

Standards Committee.
Enquiries on this document can be forwarded to:

https://customer-portal.rssb.co.uk/
Issue 5
01 December 2018
© Copyright 2018
Rail Safety and Standards Board Limited
Introduction
To meet the requirements of the European Rail Agency, the
glossary is now presented by two methods - by subject matter and
by alphabetical listing.
Terms by subject matter Page 2 to 16

Terms in alphabetical Page 17 to 30
order
Conventions used in this Example

Glossary
A black line in the margin indicates a
change to that term and is shown
when published in the glossary for
the first time
09/18 1
Terms by subject matter
Electrified Lines
Conductor rail A rail through which electricity is supplied to
electric-powered trains.
Earthed The term ‘earthed’ when applied to the
overhead line equipment which is normally
live, means connected to the traction return
running rail either directly or to a structure
which is itself connected thereto.
Electrified line A line that is electrified either by 25,000 volts
AC overhead lines or by 750 volts DC
conductor rails. Local instructions are issued
for certain sections of route electrified by
1500 volts DC overhead lines.
Isolated Electrical equipment is isolated when it is
disconnected from all sources of electricity
supply in a secure way.
Isolation Isolation is the action of causing electrical
sections or sub-sections of the OLE or CRE
to be isolated. For AC it includes the entire
process of switching off, securing, testing and
earthing and issue of the overhead line
permit. For DC it includes the entire process
of switching off, securing and testing and
issue of the conductor rail permit.
Live Connected to an electrical supply.
Overhead line Wires and associated equipment, suspended
equipment over or adjacent to the railway line for
supplying electricity to electric trains.
Switched off Electrical equipment that is disconnected and
separated from all sources of supply.
2 09/18
Engineering Work
Affect the Any activity or event that allows train working
normal passage to continue but causes diversion, inability to
of trains call at a planned destination or introduction of
degraded-mode operations such as passing
signals at danger, handsignalling, manual
route setting or single line working
arrangements.
Affect the Any activity or event that may, during its
safety of train course, render a movement control or
working interlocking system unusable for the signaling
of trains.
Engineering Includes an on-track machine.
train
Engineering A reminder applied by the signaller to one or
Possession more axle counter sections in advance of
Reminder (EPR) pre-planned engineering works in order to
indicate the area affected. When removed
from an axle counter section indicating
occupied, this initiates an unconditional reset/
restoration of the axle counter without aspect
restriction.
Intermediate A location other then the limits at the ends of
point to a the possession where an engineering train
possession can enter or leave the possession to:
• an open line
• a siding not under possession.
On-track plant A road-rail vehicle (RRV) or rail mounted
maintenance machine (RMMM) also known
as ‘in possession only’ vehicles.
Possession A double-sided board, red on both sides, with
Limit Board a red light (which may be steady or flashing).
(PLB) The board also has the word STOP printed
on both sides.
09/18 3
Track circuit A special device that can be placed on the

operating line to provide protection by operating the
device (T-COD) track circuit, to hold a signal at danger.
Incidents & Emergencies

Controlled The evacuation of passengers from a train
evacuation after the signaller has confirmed that all lines
have been protected.
Detonator A small disc-shaped warning device,
designed to be placed on the railhead for
protection and emergency purposes. It
explodes when a train passes over it.
Detonator Detonator protection consists of three
Protection detonators placed 20 metres (approx 20
yards) apart on the same rail with a
possession limit board at the first detonator in
the direction of travel.
Emergency The evacuation of passengers from a train if
evacuation the signaller states that protection cannot be
given or the signaller cannot be contacted.
Emergency The means of protecting a train by track
protection circuit operating clips, hand danger signals
and detonators when:
• a driver or guard cannot contact the
signaller, or
• the signaller cannot provide signal
protection.
Protection Ways of making sure that a line is protected.
This includes keeping signals at danger,
placing detonators on the line, using a track
circuit operating clip and showing a hand
danger signal.
Track circuit A device which, in an emergency can be
operating clip placed on top of each running rail to operate
the track circuit and protect an obstruction.
4 09/18
Uncontrolled The self evacuation of passengers from a

evacuation train, which is not initiated by the driver or
guard.
Level crossings
Automatic level Any of the following level crossings:
crossing • Automatic half-barrier (AHBC)
• Automatic barrier crossing, locally
monitored (ABCL)
• Automatic open crossing, locally
monitored (AOCL)
• Crossing with red and green warning
lights (R/G).
Barrow A crossing (often at the end of a platform) for
crossing railway personnel to use. Some barrow
crossings have white-light indicators which,
when lit, indicate to the user that it is safe to
cross.
Controlled Any of the following level crossings.
crossing • Manned crossing with barriers (MCB).
• Manned crossing with gates (MG).
• Remotely controlled crossing with barriers
(RC).
• Barrier crossing with closed-circuit
television (CCTV).
• Barrier crossing with obstacle detection
(OD).
Level crossing Any manned, automatic, controlled, or open
crossing shown in Table A of the Sectional
Appendix.
Manned level A level crossing that is operated locally by a
crossing signaller or crossing keeper (MCB or LC).
09/18 5
Open level An unmanned level crossing that has no

crossing barriers, gates or road traffic signals. It has a
‘Give Way’ sign on each road approach.
Lines, Stations and Depots

Adjacent line A line or siding next to the line you are on.
Bi-directional A line on which the signalling allows trains to
line run in both directions.
Goods line A line that has not been signalled to the
standard required for running passenger
trains.
Maintenance A location defined in a train operator’s
depot Contingency Plan with the facilities to repair
or replace specified items of defective
on-train equipment.
No-block line A line on which the signaller does not monitor
the condition of the block section.
Running line A line as shown in Table A of the Sectional
Appendix as a passenger line or as a
non-passenger line.
Siding A line on which vehicles are marshalled,
stabled, loaded, unloaded or serviced clear of
a running line.
Single line One line is available for movements in both
directions.
Station Terminal, depot, yard or halt.
Lineside Equipment
Aspect The indication of a colour light signal that the
driver sees.
6 09/18
ATWS Automatic track warning system.

An individual or lineside warning system that
can be installed at a site of work to:
• detect an approaching train
• alert personnel who are on or near the
line.
It may be installed temporarily for the period
of work or it may be installed permanently at
a location. This definition does not include
TOWS or LOWS
Automatic A signal operated by the passage of trains.
Signal The signaller or a person operating a signal
post replacement switch can place some
automatic signals to danger.
Axle counter A method of detecting the presence of a train
or vehicle on a line. Track-mounted
equipment, at each end of a portion of line,
counts the number of axles passing over.
This is used to identify when a portion of line
is occupied or clear.
Axle counter A device that detects the passage of a wheel
head passing over a running rail.
Block marker Reflective board that serves as a physical
indication of signalling sections within
ERTMS. Used when degraded working is
required.
Home signal The first stop signal on the approach to a
signal box on a line not signalled by the track
circuit block system of signalling.
Interlocking A general term applied to equipment that
controls setting and releasing signals and
points to prevent an unsafe condition of the
signalling system arising during the passage
of trains.
09/18 7
Intermediate A stop signal that controls the exit from an

block home intermediate block section. (Although an
signal intermediate block home signal controls the
entrance to an absolute block section, it is
referred to as the intermediate block home
signal).
Junction signal A signal that controls more than one running
route and can display an indication of route.
LOWS Lookout operated warning system. A lineside
warning system, used to warn personnel on
or near the line about an approaching train. It
is operated by a lookout.
Main aspect The following aspects of a colour light signal:
• red
• yellow
• two yellows
• flashing yellow
• two flashing yellows
• green.
PoSA Proceed-on-sight authority. A signal used for
controlling movements into a section affected
by a failure of signalling equipment.
Right-side A failure that does not reduce the protection
failure given by signalling equipment.
Section signal A stop signal that controls the entrance to a
block section or intermediate block section
ahead.
Semi-automatic A signal normally operated by the passage of
signal trains, but can also be controlled from the
signal box or from a ground frame, or by a
person operating a signal post replacement
switch.
8 09/18
Shunt entry A lineside indicator board that indicates the

board entry of a shunt route on ERTMS cab
signalled lines where lineside signals are not
provided.
Shunting signal A signal that is provided for shunting
purposes only.
Signal post The key used to operate a signal post
replacement replacement switch.
key
Signal post A switch on the post of an automatic or
replacement semi-automatic colour light signal that can be
switch operated by a key to turn it to, and keep it at,
danger.
Stop signal A signal that can show a stop aspect or
indication.
Subsidiary A semaphore signal used for controlling
signal shunting movements and movements onto
occupied tracks. It is always positioned below
the main semaphore arm with which it is
associated.
TOWS Train operated warning system. An audible
warning system at locations listed in the
Sectional Appendix. When switched on, it is
used to warn personnel on or near the line
about an approaching train.
TPWS Train protection and warning system. A
system by which a train is stopped by an
automatic application of the brakes when
activated by lineside equipment.
Track circuit A method of detecting the presence of a train
or vehicle on a line. An electrical device,
using the rails as an electrical circuit, detects
the absence of a train or vehicle. If these
rules refer to track circuits, this also includes
detection by axle counters unless specially
excluded.
09/18 9
Wrong-side A failure that reduces or removes the

failure protection given by signalling equipment.
Points
Catch points Points designed to derail vehicles running
back on a gradient in the wrong direction.
These points may be unworked if trains
normally pass over them in one direction
only.
Derailer A device at an exit from a siding or bay
platform that derails an unauthorised
movement.
Detection An electrical or mechanical indication that
points are set in the correct position.
Facing point Equipment that physically locks facing points
lock so that they cannot move.
Facing points Points where two routes diverge.
Ground frame A control point containing levers or switches
to allow points in running lines and sidings,
and any associated signals, to be operated
locally. This local operation is only possible
when the signaller at the controlling signal
box gives a release. Also includes a
ground-switch panel.
Hand points Points that are worked manually by lever
independent of any other signalling controls.
Mechanical Points that are mechanically operated without
points any other form of power operation.
Power-operated Points that are operated by means other than
points mechanically.
Run through (of An incident where a movement runs through
points) a trailing set of points that are not set in the
correct position for the movement.
Trailing points Points where two routes converge.
10 09/18
Train-operated Points that are continuously driven to one

points position such that facing movements always
pass through them in the same direction.
Trains themselves operate the points in the
trailing reverse direction.
Trap points Facing points at an exit from a siding or
converging route that derail an unauthorised
movement, so protecting the adjacent line.
Unworked Points that are not operated from a signal box
points or ground frame.
Worked points Points that are operated from a signal box or
ground frame.
Train Signalling Regulations

Absolute block A signalling system that allows only one train
to be in a block section at the same time. The
block indicator is used to indicate whether the
line between adjacent signal boxes is clear or
occupied.
Block section The section of the line between the section
signal of one signal box and the home signal
of the next signal box ahead.
ERTMS European rail traffic management system. A
signalling system that uses in cab indications
as opposed to external track bourne signals.
Intermediate The line between the section signal and the
block section intermediate block home signal worked by the
same signal box in the same direction of
travel.
Overlap The distance beyond a stop signal up to
which the line must be clear before the
previous signal can show a proceed aspect.
Route setting Location on a signalling control panel or
position workstation from which a route can be set or
closed.
09/18 11
Station limits The line between the home signal and the
section signal worked by the same signal box
and in the same direction of travel. This does
not apply on a track circuit block line.
Track circuit A method of signalling trains in a section of
block line using track circuits or other means of
automatic train absence detection and
without using block instruments.
Train signalling Instructions for use by the signaller that give
regulations details of the rules, regulations and
instructions relating to each different kind of
signalling system.
Transition The process of the onboard ERTMS signaling
system transferring from one signalling
system to another. This process has to be
acknowledged by the driver.
Train Working
Braking The distance a train needs in which to stop or
distance reduce speed, from travelling at a given
speed.
Coupled in Traction units coupled to allow through
multiple controls by one driver.
Coupled in Each traction unit is separately controlled by
tandem its own driver, with through control of the
automatic brake only.
Driver only (or A train that is worked only by a driver and
DO) train does not have a guard.
In service A train is in service from the time it is ready to
start its journey until the time it completes its
journey. A vehicle is in service when it forms
part of a train which is in service.
End of authority The location to which a train is permitted to
proceed. The boundary of a movement
authority.
12 09/18
Full supervision The normal movement used by ERTMS, an

authority that gives comprehensive protection
to all trains.
Journey The route from the starting point of a train
(siding, platform line or other place) to its
planned destination (siding, platform line or
other place), or where:
• is required to reverse before continuing to
its destination
• vehicles are attached or detached
• it is terminated short of its destination.
Any light locomotive movement, empty
coaching stock movement or short distance
shunting movement is a separate journey
from the associated train movement.
Movement Permission for a train to run to a specific
authority location as a signalled move.
On sight A type of movement authority used by
ERTMS that allows entry into an occupied
section. The driver will be presented with a
maximum speed and must ensure that the
train is stopped short of any obstruction.
One-train Method of signalling on a single line, with or
working without a train staff, where only one train at a
time is permitted.
Out of service A train is out of service between the time that
(train) it completes its journey and the time it is
ready to start another journey.
Out of service A vehicle is out of service when it forms part
(vehicle) of a train that is out of service, or when it has
been detached from a train in a depot, siding,
platform line or other authorised place. The
detraining of passengers does not in itself
mean a vehicle has been taken out of
service.
09/18 13
Passenger A train that is in service carrying passengers.

service
Permissible The maximum permitted speed as shown in
speed the Sectional Appendix.
Shunting Any movement of a train or vehicle other than
movement a train passing normally along a running line.
Tail lamp Includes an illuminated built-in red light or
blind.
Token Any single line token, staff or tablet.
Trains
Brake van Any vehicle with a brake compartment.
Cant rail The point on the side of a locomotive or
coach where the bodyside meets the roof
(sometimes marked by an orange stripe).
Central door- A secondary locking system fitted to certain
locking slam-door passenger vehicles and controlled
by the guard that prevents passengers from
opening the doors.
Defective on- On-train equipment that:
train equipment • is not performing its intended
safetyfunction, either fully or partly
• is isolated
• is missing.
Driver machine The device used by a driver to interact with
interface (DMI) ERTMS onboard equipment. Typically a
computer screen located in the driving cab.
Driver’s A device in a driving cab that allows the driver
reminder to set a reminder that the signal ahead is at
appliance (DRA) danger. While the DRA is set, the driver
cannot take power.
Power-operated Doors on a train where the opening and
doors closing are controlled by the driver or guard.
14 09/18
TASS Tilt authorisation and speed supervision. A

system on tilting trains that controls:
• the operation of the tilt system
• the speed of the train on routes where
enhanced permissible speeds apply on
TASS fitted lines.
Track circuit Equipment provided on certain trains to
actuator improve the operation of track circuits.
Traction unit Locomotive, multiple unit, self-propelled rail
vehicle or road-rail vehicle operating in rail
mode.
Train This includes light locomotive, self-propelled
rail vehicle or road-rail vehicle in rail mode.
Workforce
Competent A person who is passed as being qualified
person and has the required knowledge and skills to
carry out a particular rule, regulation,
instruction or procedure.
Operations The term used for Network Rail Operations
control Control Offices.
Pilotman A person who has been appointed to manage
the passage of trains over a single line during
a failure of equipment, during repairs or due
to an obstruction.
Rolling stock A person who is authorised and has the
technician necessary technical competence to examine
or repair specified items of equipment forming
part of a train or vehicle.
Traincrew Driver and guard.
09/18 15
Train operator The company responsible for operating a

train.
Your employer The company, or subsidiary of a larger
organisation for whom you work.
16 09/18
A
Absolute block A signalling system that allows only one train
to be in a block section at the same time. The
block indicator is used to indicate whether the
line between adjacent signal boxes is clear or
occupied.
Adjacent line A line or siding next to the line you are on.
Affect the Any activity or event that allows train working
normal passage to continue but causes diversion, inability to
of trains call at a planned destination or introduction of
degraded-mode operations such as passing
signals at danger, handsignalling, manual
route setting or single line working
arrangements.
safety of the course, render the track, the formation or a
line structure unsafe for the passage of trains, or
unsafe for the passage of trains at normal
speed.
safety of train course, render a movement control or
working interlocking system unusable for the signaling
of trains.
Aspect The indication of a colour light signal that the
driver sees.
09/18 17
Terms by alphabetical order
ATWS Automatic track warning system.

An individual or lineside warning system that
can be installed at a site of work to:
• detect an approaching train
• alert personnel who are on or near the
line.
It may be installed temporarily for the period
of work or it may be installed permanently at
a location. This definition does not include
TOWS or LOWS
Automatic level Any of the following level crossings:
crossing • Automatic half-barrier (AHBC)
• Automatic barrier crossing, locally
monitored (ABCL)
• Automatic open crossing, locally
monitored (AOCL)
• Crossing with red and green warning
lights (R/G).
Automatic A signal operated by the passage of trains.
Signal The signaller or a person operating a signal
post replacement switch can place some
automatic signals to danger.
Axle counter A method of detecting the presence of a train
or vehicle on a line. Track-mounted
equipment, at each end of a portion of line,
counts the number of axles passing over.
This is used to identify when a portion of line
is occupied or clear.
Axle counter A device that detects the passage of a wheel
head passing over a running rail.
18 09/18
B
Barrow A crossing (often at the end of a platform) for
crossing railway personnel to use. Some barrow
crossings have white-light indicators which,
when lit, indicate to the user that it is safe to
cross.
Bi-directional A line on which the signalling allows trains to
line run in both directions.
Block marker Reflective board that serves as a physical
indication of signalling sections within
ERTMS. Used when degraded working is
required.
Block section The section of the line between the section
signal of one signal box and the home signal
of the next signal box ahead.
Brake van Any vehicle with a brake compartment.
Braking The distance a train needs in which to stop or
distance reduce speed, from travelling at a given
speed.
C
Catch points Points designed to derail vehicles running
back on a gradient in the wrong direction.
These points may be unworked if trains
normally pass over them in one direction
only.
Cant rail The point on the side of a locomotive or
coach where the bodyside meets the roof
(sometimes marked by an orange stripe).
Central door- A secondary locking system fitted to certain
locking slam-door passenger vehicles and controlled
by the guard that prevents passengers from
opening the doors.
09/18 19
Competent A person who is passed as being qualified

person and has the required knowledge and skills to
carry out a particular rule, regulation,
instruction or procedure.
Conductor rail A rail through which electricity is supplied to
electric-powered trains.
Controlled Any of the following level crossings.
crossing • Manned crossing with barriers (MCB).
• Manned crossing with gates (MG).
• Remotely controlled crossing with barriers
(RC).
• Barrier crossing with closed-circuit
television (CCTV).
• Barrier crossing with obstacle detection
(OD).
Controlled The evacuation of passengers from a train
evacuation after the signaller has confirmed that all lines
have been protected.
Coupled in Traction units coupled to allow through
multiple controls by one driver.
Coupled in Each traction unit is separately controlled by
tandem its own driver, with through control of the
automatic brake only.
D
Defective on- On-train equipment that:
train equipment • is not performing its intended
safetyfunction, either fully or partly
• is isolated
• is missing.
Derailer A device at an exit from a siding or bay
platform that derails an unauthorised
movement.
20 09/18
Detection An electrical or mechanical indication that

points are set in the correct position.
Detonator A small disc-shaped warning device,
designed to be placed on the railhead for
protection and emergency purposes. It
explodes when a train passes over it.
Detonator Detonator protection consists of three
Protection detonators placed 20 metres (approx 20
yards) apart on the same rail with a
possession limit board at the first detonator in
the direction of travel.
Driver only (or A train that is worked only by a driver and
DO) train does not have a guard.
Driver machine The device used by a driver to interact with
interface (DMI) ERTMS onboard equipment. Typically a
computer screen located in the driving cab.
Driver’s A device in a driving cab that allows the driver
reminder to set a reminder that the signal ahead is at
appliance (DRA) danger. While the DRA is set, the driver
cannot take power.
E
Earthed The term ‘earthed’ when applied to the
overhead line equipment which is normally
live, means connected to the traction return
running rail either directly or to a structure
which is itself connected thereto.
Electrified line A line that is electrified either by 25,000 volts
AC overhead lines or by 750 volts DC
conductor rails. Local instructions are issued
for certain sections of route electrified by
1500 volts DC overhead lines.
Emergency The evacuation of passengers from a train if
evacuation the signaller states that protection cannot be
given or the signaller cannot be contacted.
09/18 21
Emergency The means of protecting a train by track

protection circuit operating clips, hand danger signals
and detonators when:
• a driver or guard cannot contact the
signaller, or
• the signaller cannot provide signal
protection.
End of authority The location to which a train is permitted to
proceed. The boundary of a movement
authority.
Engineering A reminder applied by the signaller to one or
Possession more axle counter sections in advance of
Reminder (EPR) pre-planned engineering works in order to
indicate the area affected. When removed
from an axle counter section indicating
occupied, this initiates an unconditional reset/
restoration of the axle counter without aspect
restriction.
Engineering Includes an on-track machine.
train
ERTMS European rail traffic management system. A
signalling system that uses in cab indications
as opposed to external track bourne signals.
F
Facing point Equipment that physically locks facing points
lock so that they cannot move.
Facing points Points where two routes diverge.
Full supervision The normal movement used by ERTMS, an
authority that gives comprehensive protection
to all trains.
22 09/18
G
Goods line A line that has not been signalled to the
standard required for running passenger
trains.
Ground frame A control point containing levers or switches
to allow points in running lines and sidings,
and any associated signals, to be operated
locally. This local operation is only possible
when the signaller at the controlling signal
box gives a release. Also includes a
ground-switch panel.
H
Hand points Points that are worked manually by lever
independent of any other signalling controls.
Home signal The first stop signal on the approach to a
signal box on a line not signalled by the track
circuit block system of signalling.
I
In service A train is in service from the time it is ready to
start its journey until the time it completes its
journey. A vehicle is in service when it forms
part of a train which is in service.
Interlocking A general term applied to equipment that
controls setting and releasing signals and
points to prevent an unsafe condition of the
signalling system arising during the passage
of trains.
Intermediate A stop signal that controls the exit from an
block home intermediate block section. (Although an
signal intermediate block home signal controls the
entrance to an absolute block section, it is
referred to as the intermediate block home
signal).
09/18 23
Intermediate The line between the section signal and the

block section intermediate block home signal worked by the
same signal box in the same direction of
travel.
Intermediate A location other then the limits at the ends of
point to a the possession where an engineering train
possession can enter or leave the possession to:
• an open line
• a siding not under possession.
Isolated Electrical equipment is isolated when it is
disconnected from all sources of electricity
supply in a secure way.
Isolation Isolation is the action of causing electrical
sections or sub-sections of the OLE or CRE
to be isolated. For AC it includes the entire
process of switching off, securing, testing and
earthing and issue of the overhead line
permit. For DC it includes the entire process
of switching off, securing and testing and
issue of the conductor rail permit.
J
Journey The route from the starting point of a train
(siding, platform line or other place) to its
planned destination (siding, platform line or
other place), or where:
• is required to reverse before continuing to
its destination
• vehicles are attached or detached
• it is terminated short of its destination.
Any light locomotive movement, empty
coaching stock movement or short distance
shunting movement is a separate journey
from the associated train movement.
24 09/18
Junction signal A signal that controls more than one running

route and can display an indication of route.
L
Level crossing Any manned, automatic, controlled, or open
crossing shown in Table A of the Sectional
Appendix.
Lever Includes a switch, button or workstation
control.
Live Connected to an electrical supply.
LOWS Lookout operated warning system. A lineside
warning system, used to warn personnel on
or near the line about an approaching train. It
is operated by a lookout.
M
Main aspect The following aspects of a colour light signal:
• red
• yellow
• two yellows
• flashing yellow
• two flashing yellows
• green.
Maintenance A location defined in a train operator’s
depot Contingency Plan with the facilities to repair
or replace specified items of defective
on-train equipment.
Manned level A level crossing that is operated locally by a
crossing signaller or crossing keeper (MCB or LC).
Mechanical Points that are mechanically operated without
points any other form of power operation.
Movement Permission for a train to run to a specific
authority location as a signalled move.
09/18 25
N
No-block line A line on which the signaller does not monitor
the condition of the block section.
O
On sight A type of movement authority used by
ERTMS that allows entry into an occupied
section. The driver will be presented with a
maximum speed and must ensure that the
train is stopped short of any obstruction.
One-train Method of signalling on a single line, with or
working without a train staff, where only one train at a
time is permitted.
On-track plant A road-rail vehicle (RRV) or rail mounted
maintenance machine (RMMM) also known
as ‘in possession only’ vehicles.
Open level An unmanned level crossing that has no
crossing barriers, gates or road traffic signals. It has a
‘Give Way’ sign on each road approach.
Operations The term used for Network Rail Operations
control Control Offices.
Out of service A train is out of service between the time that
(train) it completes its journey and the time it is
ready to start another journey.
Out of service A vehicle is out of service when it forms part
(vehicle) of a train that is out of service, or when it has
been detached from a train in a depot, siding,
platform line or other authorised place. The
detraining of passengers does not in itself
mean a vehicle has been taken out of
service.
Overhead line Wires and associated equipment, suspended
equipment over or adjacent to the railway line for
supplying electricity to electric trains.
26 09/18
Overlap The distance beyond a stop signal up to

which the line must be clear before the
previous signal can show a proceed aspect.
P
Passenger A train that is in service carrying passengers.
service
Permissible The maximum permitted speed as shown in
speed the Sectional Appendix.
Pilotman A person who has been appointed to manage
the passage of trains over a single line during
a failure of equipment, during repairs or due
to an obstruction.
PoSA Proceed-on-sight authority. A signal used for
controlling movements into a section affected
by a failure of signalling equipment.
Possession A double-sided board, red on both sides, with
Limit Board a red light (which may be steady or flashing).
(PLB) The board also has the word STOP printed
on both sides.
Power-operated Doors on a train where the opening and
doors closing are controlled by the driver or guard.
Power-operated Points that are operated by means other than
points mechanically.
Protection Ways of making sure that a line is protected.
This includes keeping signals at danger,
placing detonators on the line, using a track
circuit operating clip and showing a hand
danger signal.
R
Reminder A device or control used to remind the
appliance signaller that a particular lever, button or
switch must not be operated at all, or used
only under certain conditions.
09/18 27
Repeater (in a A dial or indicator in a manual signal box that

signal box) shows the position of a signal arm and
whether the signal lamp is lit.
Right-side A failure that does not reduce the protection
failure given by signalling equipment.
Rolling stock A person who is authorised and has the
technician necessary technical competence to examine
or repair specified items of equipment forming
part of a train or vehicle.
Route setting Location on a signalling control panel or
position workstation from which a route can be set or
closed.
Running line A line as shown in Table A of the Sectional
Appendix as a passenger line or as a
non-passenger line.
Run through (of An incident where a movement runs through
points) a trailing set of points that are not set in the
correct position for the movement.
S
Section signal A stop signal that controls the entrance to a
block section or intermediate block section
ahead.
Semi-automatic A signal normally operated by the passage of
signal trains, but can also be controlled from the
signal box or from a ground frame, or by a
person operating a signal post replacement
switch.
Shunt entry A lineside indicator board that indicates the
board entry of a shunt route on ERTMS cab
signalled lines where lineside signals are not
provided.
Shunting Any movement of a train or vehicle other than
movement a train passing normally along a running line.
28 09/18
Shunting signal A signal that is provided for shunting

purposes only.
Siding A line on which vehicles are marshalled,
stabled, loaded, unloaded or serviced clear of
a running line.
Signal post The key used to operate a signal post
replacement replacement switch.
key
Signal post A switch on the post of an automatic or
replacement semi-automatic colour light signal that can be
switch operated by a key to turn it to, and keep it at,
danger.
Single line One line is available for movements in both
directions.
Station Terminal, depot, yard or halt.
Station limits The line between the home signal and the
section signal worked by the same signal box
and in the same direction of travel. This does
not apply on a track circuit block line.
Stop signal A signal that can show a stop aspect or
indication.
Subsidiary A semaphore signal used for controlling
signal shunting movements and movements onto
occupied tracks. It is always positioned below
the main semaphore arm with which it is
associated.
Switched off Electrical equipment that is disconnected and
separated from all sources of supply.
T
Tail lamp Includes an illuminated built-in red light or
blind.
09/18 29
TASS Tilt authorisation and speed supervision. A

system on tilting trains that controls:
• the operation of the tilt system
• the speed of the train on routes where
enhanced permissible speeds apply on
TASS fitted lines.
Token Any single line token, staff or tablet.
TOWS Train operated warning system. An audible
warning system at locations listed in the
Sectional Appendix. When switched on, it is
used to warn personnel on or near the line
about an approaching train.
Track circuit A method of detecting the presence of a train
or vehicle on a line. An electrical device,
using the rails as an electrical circuit, detects
the absence of a train or vehicle. If these
rules refer to track circuits, this also includes
detection by axle counters unless specially
excluded.
Track circuit Equipment provided on certain trains to
actuator improve the operation of track circuits.
Track circuit A method of signalling trains in a section of
block line using track circuits or other means of
automatic train absence detection and
without using block instruments.
Track circuit A device which, in an emergency can be
operating clip placed on top of each running rail to operate
the track circuit and protect an obstruction.
Track circuit A special device that can be placed on the
operating line to provide protection by operating the
device (T-COD) track circuit, to hold a signal at danger.
30 09/18
Traction unit Locomotive, multiple unit, self-propelled rail

vehicle or road-rail vehicle operating in rail
mode.
Trailing points Points where two routes converge.
Train This includes light locomotive, self-propelled
rail vehicle or road-rail vehicle in rail mode.
Traincrew Driver and guard.
Train-operated Points that are continuously driven to one
points position such that facing movements always
pass through them in the same direction.
Trains themselves operate the points in the
trailing reverse direction.
Train operator The company responsible for operating a
train.
Train signalling Instructions for use by the signaller that give
regulations details of the rules, regulations and
instructions relating to each different kind of
signalling system.
Transition The process of the onboard ERTMS signaling
system transferring from one signalling
system to another. This process has to be
acknowledged by the driver.
Trap points Facing points at an exit from a siding or
converging route that derail an unauthorised
movement, so protecting the adjacent line.
U
Uncontrolled The self evacuation of passengers from a
evacuation train, which is not initiated by the driver or
guard.
Unworked Points that are not operated from a signal box
points or ground frame.
09/18 31
W
Worked points Points that are operated from a signal box or
ground frame.
Wrong-side A failure that reduces or removes the
failure protection given by signalling equipment.
Y
Your employer The company, or subsidiary of a larger
organisation for whom you work.
32 09/18
Email https://customer-
portal.rssb.co.uk/
Tel +44 (0) 20 3142 5300
Twitter @RSSB_rail
Web www.rssb.co.uk
Rail Safety Standards Board

Limited
The Helicon
One South Place
London
EC2M 2RB

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Terms by subject matter Page 2 to 16

Conventions used in this Example

Track circuit A special device that can be placed on the

Incidents & Emergencies

Uncontrolled The self evacuation of passengers from a

Open level An unmanned level crossing that has no

Lines, Stations and Depots

ATWS Automatic track warning system.

Intermediate A stop signal that controls the exit from an

Shunt entry A lineside indicator board that indicates the

Wrong-side A failure that reduces or removes the

Train-operated Points that are continuously driven to one

Train Signalling Regulations

Full supervision The normal movement used by ERTMS, an

Passenger A train that is in service carrying passengers.

TASS Tilt authorisation and speed supervision. A

Train operator The company responsible for operating a

ATWS Automatic track warning system.

Competent A person who is passed as being qualified

Detection An electrical or mechanical indication that

Emergency The means of protecting a train by track

Intermediate The line between the section signal and the

Junction signal A signal that controls more than one running

Overlap The distance beyond a stop signal up to

Repeater (in a A dial or indicator in a manual signal box that

Shunting signal A signal that is provided for shunting

TASS Tilt authorisation and speed supervision. A

Traction unit Locomotive, multiple unit, self-propelled rail

Rail Safety Standards Board

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