SIST EN 50668:2021

SLOVENSKI STANDARD
SIST EN 50668:2021
01-junij-2021
Železniške naprave - Signalni in kontrolni sistemi za urbane železniške sisteme, ki
niso v sistemu UGTMS
Railway applications - Signalling and control systems for non UGTMS Urban Rail
systems
Bahnanwendungen - Nicht UGTMS Signal- und Zugbeeinflussungssysteme für den
städtischen schienengebundenen Personennahverkehr
Applications ferroviaires - Systèmes de signalisation et de contrôle pour systèmes
ferroviaires urbains non-UGTMS
Ta slovenski standard je istoveten z: EN 50668:2019
ICS:
35.240.60 Uporabniške rešitve IT v IT applications in transport
prometu
45.020 Železniška tehnika na Railway engineering in
splošno general
SIST EN 50668:2021 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 50668:2021

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SIST EN 50668:2021

EUROPEAN STANDARD EN 50668

NORME EUROPÉENNE

EUROPÄISCHE NORM
July 2019
ICS 93.100
English Version
Railway applications - Signalling and control systems for non
UGTMS Urban Rail systems
Applications ferroviaires - Systèmes de signalisation et de Bahnanwendungen - Signal- und Zugsteuerungssysteme
contrôle pour systèmes ferroviaires urbains non-UGTMS für städtische Schienenbahnsysteme ohne UGTMS
This European Standard was approved by CENELEC on 2019-07-08. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.



European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN 50668:2019 E

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EN 50668:2019
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms, definitions and abbreviations . 5
3.1 Terms and definitions . 5
3.2 Abbreviations . 6
4 General provisions and boundary conditions . 7
4.1 General . 7
4.2 Independent point control . 8
4.3 Single track section control . 9
4.4 Level crossing control . 9
4.5 Route control . 9
5 Hazards to be covered . 9
5.1 General . 9
5.2 Independent point area . 10
5.3 Single track section area . 11
5.4 Level crossing area . 12
5.5 Route control area . 13
5.5.1 Hazardous situations in TOS/GOA0. 13
5.5.2 Hazardous situations in NTO/GOA1a . 15
6 Functional requirements . 16
6.1 General . 16
6.2 Independent point control . 16
6.2.1 General . 16
6.2.2 Set and interlock points . 17
6.2.3 Signalling of points. 18
6.3 Single track section control . 19
6.3.1 General . 19
6.3.2 Set and secure single track section . 20
6.3.3 Signalling of single track section. 21
6.4 Level Crossing Control . 21
6.4.1 General . 21
6.4.2 Set level crossings . 22
6.4.3 Signalling of level crossings for rail traffic . 23
6.5 Route control . 24
6.5.1 General . 24
6.5.2 Set and secure routes . 25
6.5.3 Display movement authority . 27
6.6 Interface with signal aspects of road traffic controller . 28
Bibliography . 29

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EN 50668:2019
European foreword
This document [EN 50668:2019] has been prepared by CLC/SC 9XA “Communication, signalling and
processing systems” of CLC/TC 9X “Electrical and electronic applications for railways”.
The following dates are fixed:
• latest date by which the existence of this document has to (doa) 2020-01-08
be announced at national level
• latest date by which this document has to be implemented (dop) 2020-07-08
at national level by publication of an identical national
standard or by endorsement
• latest date by which the national standards conflicting with (dow) 2022-07-08
this document have to be withdrawn
This document has been prepared under a mandate (M/486) given to CENELEC by the European Commission
and the European Free Trade Association.
The 2013 CEN/CLC Guide 26, Railway applications – Preparation of standards for urban rail systems design,
construction, manufacture, operations and maintenance, has been used as guidance for the preparation of this
document.
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Introduction
This document covers systems restricted to on-sight train operation (TOS/GOA0) and non-automated train
operations (NTO/GOA1 with intermittent supervision), and covers signalling on tramways and other urban rail
systems which do not fall directly within either existing railway or highway standards. This would typically be for
parts of systems which are along off-street alignment, and which operate to line of sight, or automatic interlock
signalling with intermittent train control (i.e. as defined in the EN 62290 series, GOA0 and GOA1 with
intermittent supervision systems). This document does not conflict with the scope and requirements of the
EN 62290 series.
This document proposes the minimum required functions of signalling systems for guided urban system
operating line of sight and non-automated operations.
This document does not set any operational rules, any system architecture or any rules for application conditions
of technical systems for the different categories of urban rail systems.
In this document GOA1a describes a GOA1 with intermittent supervision systems.
This document covers all GOA0 and GOA1a urban guided transport systems.
Such systems require more functionality and a better safety level than that provided by traffic signal controllers
(as set out in EN 12675) but avoid the requirements inherent in railway signalling systems which from a tramway
perspective may be restrictive operationally and financially.
Numerous states in Europe use these systems to control points, manage train movements along single lines
and prevent conflicts at junctions as well as on at grade crossings with road and pedestrian traffic. Whilst
adopting much of the functional requirements and safeguards used in standard traffic signal controllers, there
is additional functionality required and currently in use to fulfil the needs of urban rail.
Mainline railway signalling systems include a lot of such additional functionality, but in terms of this and the
required safety integrity, they are not ideally suited to the needs of urban rail.
The two fundamentally different approaches for the design of signalling systems are:
• technology as used for traffic signal controllers, or
• technology as used for signalling systems to be developed in accordance with Safety Integrity Levels
sufficient for tramways and urban rail,
both of which are currently in use to some extent on most systems. This may leave system owners and operators
vulnerable to challenge, particularly after an incident, because there is no relevant accepted standard to justify
appropriate use of such equipment.
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1 Scope
This document specifies minimum functional requirements for urban rail signalling and control systems:
• which operate on line of sight or using automatic interlock signalling with intermittent train control,
• not covered by the existing UGTMS standard EN 62290 series,
• not forming a part of an urban traffic control system but possibly interfaced with such systems.
The document is restricted to minimum functional requirements which allow users to define more specific
requirements based on the given framework of the system requirements at top level. This document is not
applicable to command and control systems for urban rail using continuous data transmission and continuous
supervision of train movements by train protection profile (already covered by the EN 62290 series).
2 Normative references
There are no normative references in this document.
3 Terms, definitions and abbreviations
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• ISO Online browsing platform: available at http://www.iso.org/obp
• IEC Electropedia: available at http://www.electropedia.org/
3.1 Terms and definitions
3.1.1
external device
device providing external demand inputs to elements of signalling control
Note 1 to entry: The methods of making these demand inputs can vary from simple manual inputs to automatic data
derived inputs from train-borne equipment.
Note 2 to entry: Example of external device:
• Remote inputs from control rooms;
• Input from road traffic controller;
• A request transmitted from a train.
3.1.2
level crossing
level grade crossing
crossing of a urban rail system and a road at the same level
Note 1 to entry: In some member states when a tramway on its own alignment crosses a road used by other traffic it does
not normally do so as a level crossing within the meanings of national road and rail traffic legislation, but is usually termed
a road junction or crossing at grade. References to level crossing in this document equate to a crossing at grade when the
urban rail system under consideration is a tramway.
[SOURCE: IEC 60050-821:2017, 821-07-01, modified – Note 1 to entry has been added.]
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3.1.3
level crossing area
portion of the level crossing between the road stop lines on either side of the urban rail system
3.1.4
road traffic
road vehicles, pedestrians, equestrians, bicycles and any other road users
3.1.5
route
predefined path for a traffic movement
Note 1 to entry: This is as distinct from the meaning in railway signalling of a route. With respect to TOS/GOA0, the driver
is the person in charge of the vehicle and is required to be able to stop the train within his sighting distance.
[SOURCE: IEC 60050-821:2017, 821-01-22, modified – Note 1 to entry has been added]
3.1.6
signal
apparatus by means of which a conventional indication is given
Note 1 to entry: This conventional indication, visual or acoustic, generally concerning the movements of urban rail
vehicles, is transmitted to the staff entrusted to observe it.
Note 2 to entry: When a tramway track or part of a tramway route is in an area which is part of the highway or public road
it may not be called a signal under some national legislation unless it complies with prescribed diagrams and usage to
control traffic. Equipment used only to confirm such things as the lie and interlocking of points may therefore described in
some countries as a point indicator. In this document where the terms point signal or point interlocking signal appear, it shall
be taken that these refer to a point indicator or point interlocking indicator as appropriate.
[SOURCE: IEC 60050-821:2017, 821-02-01, modified – Note 2 to entry has been added]
3.1.7
train
combination of rolling stock coupled together
Note 1 to entry: Rolling stock includes banking locomotives.
Note 2 to entry: The term is used in this document for all categories of urban rail, such as trams, or GOA0 or GOA1a
systems for example light rail, etc.
[SOURCE: IEC 60050-821:2017, 811-01-08, modified – Note 2 to entry has been added]
3.2 Abbreviations
For the purposes of this document, the following abbreviations apply.
GOA Grade of Automation
GOA0 Grade of Automation 0
GOA1a Grade of Automation 1 with Intermittent Supervision
HMI Human Machine Interface
NTO Non-automated Train Operation
(O) Optional
TOS Train Operations on Sight
UGTMS Urban Guided Transport Management System
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4 General provisions and boundary conditions
4.1 General
The signalling systems covered by this document and their components should be suitable for use on street
alignment or off-street alignment.
Figures 1 to 3 below provide an overview of the areas of non UGTMS Urban Rail systems for which operational
scenarios need to be considered. In each area a train passes through, specific functionality is required.
This document covers the following areas:
a) Independent points (stand-alone) used for TOS/GOA0 operations, to direct trains to different tracks of
the network.
b) Single track sections used for TOS/GOA0 operations where the guideway layout is restricted to a single
track for train movements in either direction of travel.
c) Level crossings (crossings at grade) used for both TOS/GOA0 and NTO/GOA1a operation, where a
guideway crosses public streets and/or footpaths.
d) Route control area used for:
• TOS/GOA0 where the guideway layout has a higher complexity than for independent points areas and
it is reasonable to set a route consisting of various route elements for passage of the train, to ease
operation,
• NTO/GOA1a where train movements on safe routes are compulsory.
On-sight train
Signalling
operation
System

Route Control
Level Crossing
Independent Single Track
Area
Point

External Systems
(e.g. Operations Control System, Road Traffic Controller)

Figure 1 — On-sight train operation (TOS/GOA0)
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Non-automated Train
Signalling
Operations (NTO/GOA1)
System
Route Control Area

Level Crossing

External Systems
(e.g. Operations Control System, Road Traffic Controller)


Figure 2 — Non-automated train operations (NTO/GOA1a)
On-sight train Non-automated Train
Signalling
operation Operations (NTO/GOA1)
System

Route Route Control Area
Independent Single Track
Level Crossing
Control Area
Point

Level Crossing

External Systems
(e.g. Operations Control System, Road Traffic Controller)


Figure 3 — Combined on-sight train operation (TOS/GOA0) and non-automated train operations
(NTO/GOA1a)
4.2 Independent point control
Independent point control is used to set points in different positions and to avoid points moving under trains by:
• setting and securing points,
• checking and displaying the position of points.
Independent point control is used for on-sight train operation (TOS/GOA0) and covers independent points which
may be linked together, but it is not part of a route control area.
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4.3 Single track section control
Single track section control is to prevent concurrent use of a single track section by trains travelling in opposite
directions by:
• ensuring the routes associated to single track sections are set and secured,
• signalling of single track sections.
Single track section control is used for TOS/GOA0 operation. Control of points is treated separately.
4.4 Level crossing control
Level crossing control is to prevent concurrent use of the guideway by rail and crossing road/pedestrian traffic
by:
• signalling and/or signage of level crossings for rail and road traffic, and
• when signalled, closing to road /pedestrian traffic and holding level crossing for use by rail traffic.
Level crossing control is used for both TOS/GOA0 and NTO/GOA1a operations.
Some functionalities of level crossing control are covered by route control for NTO/GOA1a operation.
4.5 Route control
Route control is used to set routes via various route elements for:
a) TOS/GOA0
the prevention of conflicting movements and points moving under trains, by:
• setting and securing all routes via level crossings, switchable (e.g. points) and non-switchable (e.g.
track sections) route elements,
• signalling of routes.
b) NTO/GOA1a
the prevention of conflicting movements and points moving under trains, by:
• setting and securing all routes via level crossings, switchable (e.g. points) and non-switchable (e.g.
crossing, track sections) route elements,
• ensuring safe separation of trains,
• signalling of routes and control of train movements at specific locations.
5 Hazards to be covered
5.1 General
Boundary conditions depending on grades of automation:
a) In TOS/GOA0 operation, it is assumed that:
• whilst operating on street alignment, conflicts with other road and pedestrian traffic are covered by
highway legislation and means of prevention (e.g. traffic signs, road traffic signals and controllers) are
therefore not part of this hazard identification,
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• the train driver is responsible for carrying out such functions, within the boundary conditions defined
by national or operational rules; The train driver is responsible for carrying out conflict with road and
pedestrian traffic,
• the separation of trains is the responsibility of the driver,
• the determination of appropriate speed to avoid collisions is the responsibility of the train driver,
• the observance of appropriate speed to avoid derailment is the responsibility of the train driver.
b) In NTO/GOA1a operation:
• trains operate on a segregated guideway,
• the separation of trains is managed through the signalling system,
• speed supervision is part of the signalling system (O).
The hazard analysis described in 5.2, 5.3, 5.4, and 5.5 is general, to support any specific hazard analysis
performed in a project.
5.2 Independent point area
Boundary conditions
• for locally set points, the driver is responsible for checking that the switching of the point is permissible, for
observing that the point is correctly positioned and to observe the permitted speed relative to the position
of the points,
• there are no conflicting train movements, only the hazards due to the point are considered.
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Table 1 — Hazard analysis for independent point area
Case Hazardous situation Unwanted Mitigation Function Remarks
occurrence
1 Remotely set point in Collision with Independent Set and
unexpected position road traffic point control interlock points
- point - detect
machine position of
point
2 Remotely set point moves Derailment Independent Set and Point interlocking
under the train interlock points
point control equipment
for passage of including train
- interlock
a train detection and
point
physical locks

a
3 Train passes point at Derailment Independent Signalling of
inappropriate speed point control points
Displayed
- point - display position supports
position of
indicator the speed
points relative to the
position of the
points
4 Train moves on guideway Collision with Independent Signalling of Optional
TOS/GOA0 road traffic point control points
- road traffic controller - Interface to - consistency
displays movement authority road traffic of road traffic
in direction divergent from controller controller
point signal, train driver aspect
continues train movement
wrongly based on road traffic
controller authorization
a
The use of point indicators is not necessary if in defined cases of low speed operation over remotely set points the
train driver is responsible for observing that the point is correctly positioned and to observe the permitted speed relative
to the position of the points.
5.3 Single track section area
Boundary conditions
• hazard analysis is limited to the section of track which is designated for bidirectional use.
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Table 2 — Hazard analysis for single track section area
Case Hazardous situation Unwanted Mitigation Function Remarks
occurrence
a
1 Conflicting train movement Collision Single track Set and secure
while trains are approaching at section control single track
the same time from both section
directions
- secure track
section in
opposite
direction
a
2 Entry of a train on the section Collision Signal for train Ensure section
with a train already on the operation on signals set to
section sight and stop.
warning
- Activate
elements
warning
(optional)
elements
3 Train moves on guideway Collision with Single track Signalling of
TOS/GOA0 other train or section control single track
road traffic section
- road traffic controller displays - Interface to
movement authority divergent road traffic - consistency
from signal for single track controller with road traffic
section, train driver continues controller aspect
train movement wrongly based
on road traffic controller
authorization
4 Train moves on guideway Derailment or Route control Signalling of
without movement authority collision route
- Train stop
device -monitor
movement at
route entrance
and at discrete
locations
a
The use of single track section control is not necessary, if:
• the single track section is sufficiently short to be observed end to end by drivers and movement speeds are low;
• movement authority is granted by operational procedures (e.g. secured by token) for temporary single track sections
(e.g. track works).
5.4 Level crossing area
Boundary conditions
• hazard analysis is limited to events affecting train movements,
• on level crossings on which priority to rail traffic is given, the road traffic should obey the road traffic
signals/signage.
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Table 3 — Hazard analysis for level crossing area
Case Hazardous situation Unwanted Mitigation Function Remarks
occurrence
a
1 Train moves on Collision with Level Crossing Closing level
guideway approaching road traffic control crossings to road
level crossing traffic
- road traffic level
- road traffic passes crossing signals
level crossing
- barriers
(optional)
b
2 Train moves on Collision with Level crossing Closing and
guideway road traffic on control holding level
level crossing crossings
- road traffic is not able - Interface with
to leave the level road traffic - potential interface
crossing due to traffic management to adjacent road
congestion traffic controllers
c
3 Road traffic have Collision with Level Crossing Signalling of level
authorization to cross road traffic control crossing for rail
the level crossing and a traffic
- signal for on-
train is arriving
sight train - authorize train
operation movement
- level crossing
supervision signal
4 Train moves on Derailment or Route control Signalling of route
guideway without collision
-monitor movement
- train stop device
movement authority
at route entrance
and at discrete
locations
a
The use of level crossing control may not be necessary, if:
• visibility between approaching train and road traffic is ensured and movement speeds are low and
• road traffic signs for level crossing give priority to train movements.
b
To indicate that this scenario is only in GOA1, and in GOA0 that the driver shall stop the train in this case.
c
For this specific situation, where there are no signals for trains or road traffic.
5.5 Route control area
5.5.1 Hazardous situations in TOS/GOA0
Boundary conditions
• separation of trains in TOS/GOA0 is the responsibility of the train driver, including avoidance of anything in
conflict with the path of a train,
• determination of speed in TOS/GOA0 is the responsibility of the train driver following operational rules
(knowledge of permitted speed, speed signs and/or point indicators, signal aspects for on-sight train
operation).
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Table 4 — Hazard analysis for TOS/GOA0 route control area
Case Ha
...