EN 12675:2017
(Main)Traffic signal controllers - Functional safety requirements
General Information
- Abstract
This European Standard specifies the functional safety requirements for traffic signal controllers. It is applicable to traffic signal control equipment permanent¬ly and temporarily installed, but excludes portable traffic control equip¬ment. Traffic signal controllers, as defined by this European Standard, are required to control conflicting traffic, both vehicular and pedestrian, e.g. junction signals, pedestrian crossings, shuttle signals, public transport signals, in a safe manner.
The electrical safety requirements and additional traffic safety requirements, the interfacing with external equip¬ment and the test methods for verifying compliance with this European Standard are contained in HD 638.
NOTE National requirements may specify special conditions for public transport signals (PT) and for any other signal that is not specified in a European Standard.
- Status
- Published
- Publication Date
- 22-Aug-2017
- Withdrawal Date
- 27-Feb-2018
- Technical Committee
- CEN/TC 226 - Road equipment
- Drafting Committee
- CEN/TC 226/WG 4 - Traffic control
- Current Stage
- 9093 - Decision to confirm - Review Enquiry
- Start Date
- 29-Jul-2024
- Completion Date
- 02-Sep-2026
Overview
EN 12675:2017 - "Traffic signal controllers - Functional safety requirements" (CEN) defines the functional safety requirements for traffic signal controllers used to manage vehicular and pedestrian traffic. The standard applies to permanently and temporarily installed traffic signal control equipment (excluding limited portable shuttle-only units) and focuses on preventing hazardous signal displays by requiring fault detection, classification and safe-state responses. Electrical safety, interfacing and test methods are addressed in the related standard EN 50556 (HD 638 referenced in earlier editions).
Key Topics
- Scope and definitions: Clear definitions for terms such as signal group, absent/unwanted signals, failure mode, major/minor fault, mode-specific operation, and time base frequency.
- Functional safety requirements: Minimum safety objectives ensuring controllers prevent or mitigate hazards from incorrect signal displays (e.g., failure to display red, conflicting green, incorrect sequences or timings).
- Diagnostic checks and monitoring: Requirements for power-up self-tests, continuous diagnostics of the controller logic, and methods of monitoring to detect faults.
- Fault classification and handling: Specification of major and minor faults, required responses (change to safe states like flashing yellow or signals off), and storage/recording of fault events.
- Conflict and absent-signal management: Rules addressing signal group conflicts (unwanted signals), absent red/green/yellow signals, and national signal regulations that may impose additional constraints.
- Safety timings and time settings: Requirements for safety-relevant timing parameters and the impact of timing faults on safe operation.
- User documentation, marking and labelling: Minimum documentation and labeling required to support safe operation, service and reprogrammable memory management.
Applications and Users
EN 12675:2017 is practical for stakeholders involved in the design, procurement, installation and maintenance of traffic control systems:
- Traffic signal manufacturers and controller designers (functional safety compliance)
- Road authorities and municipalities (specifying controllers for intersections, pedestrian crossings, shuttle signals and public transport signals)
- System integrators and central traffic management centres (ensuring safe network control and monitoring)
- Maintenance and inspection personnel (fault diagnostics, documentation and safe-state procedures)
- Test laboratories and certification bodies (verifying functional safety requirements in conjunction with EN 50556)
Related Standards
- EN 50556 - Road traffic signal systems (electrical safety, interfacing and test methods).
- National signal regulations - may define country-specific classes, sequences and additional requirements for public transport (PT) signals.
EN 12675:2017 is essential for ensuring that traffic signal controllers meet consistent, safety-focused requirements across European installations, reducing risks from signal failures and improving road-user safety.
Relations
- Effective Date
- 19-Jun-2010
- Effective Date
- 09-Feb-2026
- Referred By
EN 50556:2018 - Road traffic signal systems - Effective Date
- 09-Feb-2026
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Frequently Asked Questions
EN 12675:2017 is a standard published by the European Committee for Standardization (CEN). Its full title is "Traffic signal controllers - Functional safety requirements". This standard covers: This European Standard specifies the functional safety requirements for traffic signal controllers. It is applicable to traffic signal control equipment permanent¬ly and temporarily installed, but excludes portable traffic control equip¬ment. Traffic signal controllers, as defined by this European Standard, are required to control conflicting traffic, both vehicular and pedestrian, e.g. junction signals, pedestrian crossings, shuttle signals, public transport signals, in a safe manner. The electrical safety requirements and additional traffic safety requirements, the interfacing with external equip¬ment and the test methods for verifying compliance with this European Standard are contained in HD 638. NOTE National requirements may specify special conditions for public transport signals (PT) and for any other signal that is not specified in a European Standard.
This European Standard specifies the functional safety requirements for traffic signal controllers. It is applicable to traffic signal control equipment permanent¬ly and temporarily installed, but excludes portable traffic control equip¬ment. Traffic signal controllers, as defined by this European Standard, are required to control conflicting traffic, both vehicular and pedestrian, e.g. junction signals, pedestrian crossings, shuttle signals, public transport signals, in a safe manner. The electrical safety requirements and additional traffic safety requirements, the interfacing with external equip¬ment and the test methods for verifying compliance with this European Standard are contained in HD 638. NOTE National requirements may specify special conditions for public transport signals (PT) and for any other signal that is not specified in a European Standard.
EN 12675:2017 is classified under the following ICS (International Classification for Standards) categories: 93.080.30 - Road equipment and installations. The ICS classification helps identify the subject area and facilitates finding related standards.
EN 12675:2017 has the following relationships with other standards: It is inter standard links to EN 12675:2000, EN 50556:2011, EN 50556:2018. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
EN 12675:2017 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Krmilniki za svetlobne prometne znake - Funkcionalne varnostne zahteveSteuergeräte für Lichtsignalanlagen - Funktionale SicherheitsanforderungenContrôleurs de feux d'intersection - Prescription de sécurité fonctionnelleTraffic signal controllers - Functional safety requirements93.080.30Cestna oprema in pomožne napraveRoad equipment and installationsICS:Ta slovenski standard je istoveten z:EN 12675:2017SIST EN 12675:2017en,fr,de01-oktober-2017SIST EN 12675:2017SLOVENSKI
STANDARDSIST EN 12675:20021DGRPHãþD
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 12675
August
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{ uä r z rä u r Supersedes EN
s t x y wã t r r rEnglish Version
Traffic signal controllers æ Functional safety requirementsContrôleurs de signaux de circulation routière æ Exigences de sécurité fonctionnelle
Steuergeräte für Lichtsignalanlagen æ Funktionale Sicherheitsanforderungen This European Standard was approved by CEN on
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t r s yä
egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä
translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä
CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Serbiaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey and United Kingdomä
EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels
t r s y CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN
s t x y wã t r s y ESIST EN 12675:2017
A-deviations . 19 Bibliography . 21
— fixed time operation mode; — traffic dependent operation mode; — standby operation mode; — manual operation mode; — failure mode; 3.13 monitoring method of collecting information about the traffic signal controller including diagnostic checks used to detect a fault condition SIST EN 12675:2017
Key 1 single carriage way / bridge 2 carriageway restriction / road works Figure 1 — Example for Shuttle working lanes 4 Functional safety requirements 4.1 General This European Standard specifies the minimum safety requirements for traffic signal controllers to ensure the safe state of signals displayed to traffic. This safety consists of preventing a fault, or the consequences of a fault, that could result in the display of information liable to present a hazard to road users. A hazard to road users is prevented by the ability of the traffic signal controller to detect a specified fault condition and to change to a safe state. The change to a safe state is determined by the ability of the traffic signal controller to respond to the occurrence of faults in accordance with Clause 5. A fault condition may be dependent on the configuration of signal groups for specific application requirements. The specified fault condition shall be classified as a major or minor fault condition and acted on accordingly. Diagnostic checks shall be provided within the traffic signal controller for the detection of specified fault conditions. This is achieved by monitoring the appropriate: SIST EN 12675:2017
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