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PD CEN TS 13149 — Public Transport Road Vehicle Scheduling and Control Systems (Part 7 System and Network Architecture; Part 8 Physical Layer for IP Communication)
Public Transport — Road Vehicle Scheduling and Control Systems — System and Network Architecture / Physical Layer for IP Communication
📡 PD CEN/TS 13149 is a class of Published Documents issued by the British Standards Institution (BSI) based on the European Technical Specification CEN/TS 13149, which specifies communication and interface requirements between on-board equipment and between on-board equipment and the operational control centre of public transport road vehicle scheduling and control systems (often called fleet management or automatic vehicle location / fleet management systems, AVL/FMS). The two parts covered in this batch, PD CEN/TS 13149-7:2015 and PD CEN/TS 13149-8:2013, define respectively the system and network architecture and the physical layer supporting IP communication, together forming a key element of the communication infrastructure in an intelligent public transport dispatch system.
💡 The CEN/TS 13149 series is prepared by the European Committee for Standardization (CEN) intelligent transport systems committee. The UK participates through Technical Committee EPL/278 and publishes it as a Published Document. Such technical specifications are provisional, initially valid for about three years, after which CEN members evaluate whether to convert them into formal European Standards.
1. Overview of the Series 📌
A public transport vehicle scheduling and control system must connect many distributed on-board devices — positioning, stop announcement, on-board information, in-vehicle surveillance, on-board fare collection and data recording — into a unified information network, and exchange data with the operations management system in the control centre. The CEN/TS 13149 series is designed for exactly this “multi-device, multi-site, cross-network” open on-board communication requirement, focusing on the architectural structure of data communication and the low-level transmission implementation.
The two parts of the series in this batch are summarised below:
| Standard | Part Topic | Main Provisions | Year |
|---|---|---|---|
| PD CEN/TS 13149-7:2015 | System and Network Architecture | Overall architecture, design principles, functional layering and information-flow organisation of on-board and operational networks | 2015 |
| PD CEN/TS 13149-8:2013 | Physical Layer for IP Communication | Physical layer requirements for IP communication, including transmission medium, connectors and signal characteristics | 2013 |
⚠️ Note that other parts of CEN/TS 13149 (such as those dealing with in-vehicle buses or application-layer interfaces) are outside this batch. When applying the series in engineering, the complete set of parts should be used, so that on-board communication is not designed against only a single part.
2. Part 7: System and Network Architecture 🔗
PD CEN/TS 13149-7:2015 is the core document defining the “architecture” of the CEN/TS 13149 series, and includes terms and definitions, symbols and abbreviations, and a series of design principles. The part starts from the system as a whole and clarifies which functional entities make up the vehicle scheduling and control system, how they interconnect, and the layering approach aligned with the Open Systems Interconnection (OSI) reference model.
In terms of architecture, a dispatch and control system can typically be divided into the following functional levels:
- On-board layer: positioning terminals, stop announcement / information displays, driver terminals, in-vehicle surveillance, on-board fare collection, data recorders and similar devices;
- Communication layer: the on-board local area network and wide-area wireless communication (mobile networks, dedicated radio, etc.) that aggregate vehicle data to the control centre;
- Dispatch / operations layer: fleet monitoring, vehicle location, schedule planning, real-time arrival information, operational statistics and back-office management systems.
Part 7 focuses on the interface relationships of this “on-board — communication — operations” three-layer model, and gives the layering principles corresponding to the OSI reference model, enabling on-board subsystems from different suppliers to work together through standardised interfaces.
✅ The value of Part 7 lies in its “top-level constraint”: it does not prescribe the physical details of any particular bus, but first agrees on the network architecture and information-flow organisation, providing a unified framework for the subsequent parts (physical layer, application layer, etc.) and preventing on-board systems from being developed in isolation and failing to interconnect.
3. Part 8: Physical Layer for IP Communication 🌐
PD CEN/TS 13149-8:2013 specifies the physical layer requirements for IP communication; it is the part of the series that addresses the concrete transmission implementation. It defines the transmission medium, electrical / optical interfaces, connectors and signal characteristics that the physical layer must satisfy when data is exchanged using IP protocols in a vehicle scheduling and control system, so that the on-board local area network can reliably carry application-layer communication based on IP.
Because public transport vehicles operate in harsh environments (temperature variation, vibration, electromagnetic interference, supply-voltage fluctuation), Part 8 places targeted requirements on the physical layer’s immunity to interference, vibration and connection reliability, together with appropriate verification methods. Using mature wired Ethernet-class physical-layer technology gives the on-board network ample bandwidth and good scalability, supporting high-volume applications such as in-vehicle video surveillance, on-board information displays, stop announcement and dispatch.
⚠️ The physical layer is the “foundation” of communication. If the physical layer does not meet requirements, no matter how well designed the upper-layer protocols are, communication may suffer packet loss, bit errors or even complete interruption. Physical layer design in the on-board environment must balance bandwidth, reliability and electromagnetic compatibility.
4. Key Technical Requirements 🔧
Combining Parts 7 and 8, the key technical requirements of the series can be summarised as:
- Standardised interfaces: on-board subsystems, and the on-board system and the control centre, should exchange data through standardised interfaces and protocols to ensure interchangeability and interoperability.
- Layered implementation: following the OSI reference model, the physical, data-link and network/application layers have clearly separated responsibilities, allowing independent upgrade and maintenance.
- Reliability design: accounting for supply-voltage fluctuation, electromagnetic interference, temperature variation and vibration, reliability requirements are placed on the physical layer and connectors.
- Scalability: the network architecture should allow new equipment and services to be added gradually without rebuilding the whole system.
- Interoperability verification: communication protocols and physical interfaces are subject to conformity verification to ensure equipment from different manufacturers can work together.
5. Engineering Practice and Applications 🛠️
In urban transit intelligence upgrades, the CEN/TS 13149 series is commonly applied to:
- Fleet Management (FMS): on-board positioning terminals, driver terminals and the control centre exchange position, status and dispatch commands over an IP network;
- Intelligent dispatch: dynamically arranging departure plans based on real-time vehicle positions, supporting automatic stop announcement and operational statistical analysis;
- On-board informatisation: reliable transmission of high-volume data such as on-board information screens, in-vehicle surveillance and passenger-flow statistics;
- Multi-supplier integration: with standardised interfaces, vehicle equipment and dispatch software can be supplied by different vendors, reducing system coupling and total cost of ownership.
💡 Implementation advice: during project tendering and design, the requirements specification should explicitly reference the relevant parts of CEN/TS 13149, and suppliers should be required to provide conformity statements and interoperability test reports, locking in communication-architecture consistency before the system is built.
6. Frequently Asked Questions ❓
❓ Q: What is the difference between PD CEN/TS 13149 and a formal BS EN standard?
A: The “PD” prefix denotes a Published Document, the UK national implementation of a European Technical Specification (CEN/TS). It is provisional, initially valid for about three years, after which CEN members decide whether to convert it into a formal European Standard.
A: The “PD” prefix denotes a Published Document, the UK national implementation of a European Technical Specification (CEN/TS). It is provisional, initially valid for about three years, after which CEN members decide whether to convert it into a formal European Standard.
❓ Q: What is the relationship between Part 7 and Part 8?
A: Part 7 specifies the overall system and network architecture and design principles — the “framework”; Part 8 specifies the physical-layer implementation that IP communication relies on — the “foundation”. They are used together: first set the architecture, then set the physical layer.
A: Part 7 specifies the overall system and network architecture and design principles — the “framework”; Part 8 specifies the physical-layer implementation that IP communication relies on — the “foundation”. They are used together: first set the architecture, then set the physical layer.
❓ Q: Why does public transport on-board communication place so much emphasis on physical-layer reliability?
A: On-board equipment is long exposed to vibration, temperature change, supply-voltage fluctuation and electromagnetic interference; if the physical layer fails, the entire communication link breaks. The standard therefore sets targeted requirements for the transmission medium, interface and immunity.
A: On-board equipment is long exposed to vibration, temperature change, supply-voltage fluctuation and electromagnetic interference; if the physical layer fails, the entire communication link breaks. The standard therefore sets targeted requirements for the transmission medium, interface and immunity.
❓ Q: What benefits does IP communication bring to a transit dispatch system?
A: IP communication reuses a mature, open network protocol stack with ample bandwidth and a rich equipment ecosystem, making it easy to connect to control centres, internet applications and big-data platforms, and to extend to new services such as video and passenger-flow data later.
A: IP communication reuses a mature, open network protocol stack with ample bandwidth and a rich equipment ecosystem, making it easy to connect to control centres, internet applications and big-data platforms, and to extend to new services such as video and passenger-flow data later.
❓ Q: Is the technical specification mandatory?
A: CEN/TS is a technical specification and is not itself mandatory; but as a UK Published Document its technical requirements are often incorporated into contracts or tender documents by purchasers, thereby acquiring contractual force in specific projects.
A: CEN/TS is a technical specification and is not itself mandatory; but as a UK Published Document its technical requirements are often incorporated into contracts or tender documents by purchasers, thereby acquiring contractual force in specific projects.