ISO/TR 18155:2025
(Main)Railway applications — Principles of train detection for operations and services
Railway applications — Principles of train detection for operations and services
This document describes the general principles of train detection for operations and services which are applied to any railway. This document provides the link of train detection with management of operational principles. It includes descriptions of operational and environmental conditions affecting train detection and impacts on operations. This document provides non-technical guidance for supporting the choice of a suitable train detection method relating to railway operations, for new lines and upgrade or renewal of train detection systems. This document excludes all technical aspects.
Applications ferroviaires — Principes de détection des trains pour les opérations et services
General Information
Standards Content (Sample)
Technical
Report
ISO/TR 18155
First edition
Railway applications — Principles
2025-11
of train detection for operations
and services
Applications ferroviaires — Principes de détection des trains pour
les opérations et services
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Operational aspects regarding train detection . 1
4.1 General .1
4.2 Application situation of train detection in operations .2
4.3 Impacts of train detection on operations .2
4.3.1 Impacts of train detection on operation safety .2
4.3.2 Impacts of train detection on operation efficiency .3
4.4 Combined application of train detection methods .3
5 Application of train detection . 3
5.1 General principles of train detection related methods .3
5.1.1 Categorization .3
5.1.2 Operational characteristics .4
5.1.3 Environmental conditions .4
5.1.4 Principles under normal operation .4
5.1.5 Principles under degraded operation .5
5.1.6 Selection principles .5
5.2 Operational and environmental conditions affecting train detection methods .6
5.3 Impact of train detection method on normal and degraded operations .8
5.3.1 Operation management guidance in normal situations .8
5.3.2 Operation management guidance in degraded situations .10
5.4 Possible selection criteria for train detection method .11
5.4.1 Selection criteria .11
5.4.2 Application in practice . 12
Bibliography . 14
iii
Foreword
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iv
Technical Report ISO/TR 18155:2025(en)
Railway applications — Principles of train detection for
operations and services
1 Scope
This document describes the general principles of train detection for operations and services which are
applied to any railway. This document provides the link of train detection with management of operational
principles. It includes descriptions of operational and environmental conditions affecting train detection
and impacts on operations.
This document provides non-technical guidance for supporting the choice of a suitable train detection
method relating to railway operations, for new lines and upgrade or renewal of train detection systems.
This document excludes all technical aspects.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
train detection
safe recognition of the presence or absence of any trains on a defined section of the track or at a given point
[SOURCE: IEC 62290-1:2025, 3.1.41]
4 Operational aspects regarding train detection
4.1 General
The detection of the presence of train contributes to the avoidance of collisions and derailment. Different
methods of train detection will contribute to a different extent. Operation is dependent on the position
information of trains, therefore some means of train detection are used.
Figure 1 outlines the boundaries of train detection for operations and services.
Figure 1 — Boundaries of train detection for operations and services
4.2 Application situation of train detection in operations
Train detection has been commonly applied to most railway lines.
There are various train detection methods, which can be classified into two categories (see 5.1.1):
— signal block detection;
— single point detection.
Different train operators adopt distinct train detection methods and use several train detection methods
in some cases, in order to suit their specific operational characteristics and environmental conditions, and
further meet the operational requirements.
Train detection methods exhibit varying characteristics. Selecting appropriate train detection method is
crucial for ensuring operation safety, enhancing operation efficiency and improving operation service
quality. The selection of train detection method is based on the operational characteristics described in
5.1.2 as well as the environmental conditions specified in 5.1.3.
When a specific method of train detection is applied, the equipment supplier, relevant stakeholders and the
operator can work together to establish the application, maintenance and management rules, so as to ensure
that its functions align with the operation requirements and ensure the operation safety and efficiency
according to the operational requirements. At the same time, the operator can always observe the working
status of the train detection equipment to ensure that the train detection function is normal under the
normal operation mode (see 5.1.4). When the train detection function fails, the operator needs to switch to
the degraded operation mode (see 5.1.5) and take appropriate operation management measures.
4.3 Impacts of train detection on operations
4.3.1 Impacts of train detection on operation safety
Train detection is vital for ensuring the safety of train operations. By detecting train presence and occupancy
on tracks, operators can coordinate signalling systems to maintain safe distances between trains. This helps
prevent collisions between trains, as well as between trains and the infrastructure, which enhances overall
railway safety. The details are as follows.
a) For the management of railway operations, the operator can set up an operation control centre to
manage lines within its jurisdiction. Train detection provides information of train position across the
railway network, through which the operator can manage the specific position of each train to grant
safety movement authorities which maintain a safe distance between trains. In certain cases, these
plans need adjustment based on train location, operation time changes, and the status of trains and
lines, such as due to engineering works, failures or accidents.
b) Train detection can be used by train control system, which ensures the safety of train movement, e.g.
calculation of the safe running interval between trains, protection of level crossing with warning to users.
4.3.2 Impacts of train detection on operation efficiency
Train detection plays an important role in providing services for passengers, freight and other users,
ensuring effective capacity management, improving infrastructure utilization and ensuring operational
efficiency.
a) Through train detection, the operator can accurately track the location of the train and estimate the
arrival and departure time of the train at different locations. This information can be used for effective
train scheduling to ensure the smooth flow of trains. Accurate train detection can authorize the use and
cancellation of routes more quickly, shorten the interval between trains and minimize delays, thereby
allowing trains to operate at appropriate speeds and improve operational efficiency.
b) The train detection information is used in passenger information services to serve passengers with
their current location information and predict the arrival time according to the real-time train position
and schedule; it is provided to the freight owners in order to track the location of the freight during the
journey.
c) Train detection information is used for various purposes such as environmental monitoring, fire
alarm, etc., to improve operational services and emergency response capabilities. For example, in train
environmental monitoring, the system utilizes train location data, the total number of trains on a specific
section of track and the duration each train occupies the section; such monitoring can automatically
activate ventilation as needed.
4.4 Combined application of train detection methods
More than one train detection method can be used on the same line simultaneously. By combining different
detection accuracies in multiple ways, it is possible to ensure the continued detectability of train position
even if one detection method fails. For example, border detection can serve as a redundancy for section
detection where the line is liable to flooding.
5 Application of train detection
5.1 General principles of train detection related methods
5.1.1 Categorization
There are two main types of train detection methods, as follows:
a) Signal block detection: It is a technical method based on train detection, using signals, movement
authority or certificate to ensure that a certain distance is kept between the forward train and the
following train to ensure that there is normally only one train in each section at a time, including the
following three types:
1) Section detection: This comprises continuous detection of the presence of trains within a specific
track section, typically by a track circuit. For a plain line section, it is used to maintain the safe
tracking interval of train operation; for a station or junction, it is used to detect the continuous
multiple track sections that can be combined into a complete “route”, so as to meet the needs of
station receiving, dispatching and shunting operations and prevent conflicting routes.
2) Border detection: This is based on the borders of one or multiple consecutive block sections on a
railway line, which detect when a train passes the border, and determine the clear/occupied status
of the track sections divided by these borders through safety computing, typically by the axle
counter.
3) Manual block (where this is permitted by national rules): This means, considering a block section
between two stations, with the permission of the arrival station, the departure station grants the
train operation certification or block release, after which the section between the two stations is
placed in a blocked state. When the train arrives at the arrival station, the driver hands over the
operation certification from the departure station or the train is observed to be complete, allowing
the block to be released. The status of the block can be determined either by the train operations
staff (e.g. station manager, station operator) according to operating rules or can be partially
automated.
b) Single point detection: This is detecting the passage of trains at a specific single position on the railway
track, typically by optical detection and treadle, etc. It is typically used for level crossing protection.
5.1.2 Operational characteristics
Typical operational characteristics are as follows:
— Section block mode: There are several ways of dividing the line into track sections depending on the
train detection method.
— Train running speed: This includes such speed levels as high-speed (typically 200 km/h and above) and
lower speed.
— Train running density: The headway is changed as the train departure density is changed.
— Railway transport type: This mainly refers to main line railway (passenger or freight), metro, etc.
— Train location at the station: Station entrance, throat area, station track, station exit, etc.
— Operational facilities: This includes shunting or permissive working, etc.
— Interface conditions: This includes traction power supply interface, train detection information
transmission medium, etc.
— Infrastructure conditions: This includes subgrade area, bridge area and tunnel area, rolling area of
humped shunting yard, level crossing area, poor ballast area, etc.
5.1.3 Environmental conditions
The environment conditions include:
— climatic conditions, including air pressure, temperature, humidity, wind, rain, snow and hail, ice, solar
radiation and lightning;
— geographical conditions, including plateau area and plain area;
— maintainability conditions, including remote access for maintenance;
— physical environment factors, including electro-magnetic environment, vibrations and shocks, and
power supplies;
— other conditions, including pollution, fire protection, salt mist, sand and dust storms.
5.1.4 Principles under normal operation
5.1.4.1 When no functional failure of train detection occurs, the train detection conforms with the
following principles:
a) Train detection has the capability to detect every train type that can run on the line.
b) Train detection has the capability to detect whether each track section is occupied or clear.
c) For each train detection method, the clear safety application conditions (including operation,
maintenance, design, construction and installation, etc.) and output to the staff are defined.
d) Train detection provides the status of the train detection section to other systems and provides
information to facilitate the operation of trains.
5.1.4.2 When no functional failure of train detection occurs, operation management conforms with the
following principles:
a) Operation management assigns different train detection requirements based on line location and
operating conditions.
b) The train detection method comprehensively considers preventive maintenance and corrective
maintenance factors.
c) The train detection method meets the requirements for tracking intervals of operating trains.
5.1.5 Principles under degraded operation
5.1.5.1 When the train detection function fails, the operator needs to switch to the degraded operation
mode. In this case, the train detection conforms with the following principles:
a) When the facility is provided, train detection can detect and report its own failures and faults to allow
intervention.
b) When the train detection fails, in accordance with the fail-safe principle it cannot result in “section clear”
information being given and the failure information can be sent to the train operations or maintenance staff.
c) When the train detection device is interfered with by external factors or its own function fails, any
credible failure results in a safe state.
d) Before the train detection method recovers from the faults, continuous provision of information
necessary to maintain degraded mode operation is ensured.
5.1.5.2 In certain cases, the failure of the train detection method leads to the operation degradation mode
such as the reduction of train speed. In this case, the operational management conforms with the following
principles (refer to 5.3 for details):
a) When operating in degraded mode, the risks and consequences related to running safety are clearly
identified.
b) The operating scope of degraded mode ensures that the train can be reliably decelerated to stop.
c) The normal operation mode can be restored after all faults have been rectified, if it can be confirmed
that the train detection is working correctly.
5.1.6 Selection principles
The train detection method is suitable for the purposes for which train detection information is u
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