ERTMS, the European Railway Traffic Management System, serves as a transformative force in the landscape of rail transportation. Comprising the European Train Control System (ETCS) and the Global System for Mobile Communications – Railway (GSM-R), ERTMS is designed to modernize and standardize rail safety and efficiency. In this blog post, we will explore the components of ERTMS, delve into the historical evolution of railway signaling, and examine the crucial reasons behind the industry’s shift towards adopting this cutting-edge system. From addressing the limitations of Automatic Train Control (ATC) to fostering interoperability and enhancing capacity, ERTMS emerges as a strategic solution for the dynamic challenges of contemporary rail traffic management.
What is ERTMS?
ERTMS, the European Railway Traffic Management System, is a comprehensive solution comprising two key components:
ETCS (European Train Control System) and GSM-R (Global System for Mobile Communications – Railway):
What is ETCS(European Train Control System)
ETCS stands as a pivotal element within ERTMS. It represents the advancement of the automatic train control center(ATC), modernized and standardized to cater to the pressing needs of railway safety and efficiency in European rail transportation.
ETCS at its higher levels of implementation replaces traditional national track-side signaling systems, offering a unified approach that facilitates interoperability across diverse rail networks. It can not only transmit speed limit information directly to the driver but also monitor the driver’s response to this information.
What is GSM-R
GMS-R is a radio technology that handles the exchange of information between the ground and the train. The backbone of communication within the ERTMS framework is GSM-R. It is the backbone of communication in ERTMS systems that is Tailored specifically for railway operations. It is a GSM mobile telephone standard but runs different frequencies specifically selected for railways with some advanced functions.
GSM-R ensures reliable and secure communication between trains and control centers where drivers can speak with traffic management centers and it can also be used to convey information about maximum permitted speed. This global system for mobile communications in railways plays a crucial role in supporting the seamless functionality of ERTMS, enabling real-time data exchange and coordination.
Journey from hand signals to ERTMS
Railway signaling is a term that represents the technology employed to ensure the safe movement of trains. The backbone of railway signal technology lies in the concept that “The prevention of train collisions relies on ensuring that they are not authorized to occupy the same track section simultaneously.”
The evolution of railway signaling traces a remarkable journey from manual interventions to the sophisticated systems in place today. In the mid-nineteenth century, hand signals and stopwatch-wielding personnel were employed to prevent collisions, but accidents were frequent. The introduction of semaphores around 1900 enhanced communication between trains and signal operators.
With the advent of the electrical telegraph and telephone in the early 20th century, confirmation of a cleared track became possible, reducing the risk of accidents. Optical signals emerged in the 1930s, paving the way for the semi-automatic block system. As fixed mechanical signals replaced hand signals, the system evolved into the automatic block, eliminating the need for manual intervention.
The track circuit, invented in 1872, revolutionized detection, allowing for the continuous monitoring of block occupancy. In the 21st century, Automatic Train Protection (ATP) systems, with speed monitoring capabilities, further elevated railway safety, eventually giving rise to fully driverless Automatic Train Control (ATC) systems. The historical progression, marked by technological innovations, underscores the relentless pursuit of safety and efficiency in railway signaling.
Why ERTMS? Exploring the Shift in Rail Traffic Management
In the ever-evolving landscape of rail transportation, the adoption of the European Rail Traffic Management System (ERTMS) emerges as a strategic move for various compelling reasons. Let’s delve into the key factors that underscore the shift towards ERTMS.
ATC Limitations at High Speeds:
- One primary catalyst for transitioning to ERTMS lies in the limitations of Automatic Train Control (ATC) systems, which are not approved for speeds exceeding 200 km/h. As high-speed rail becomes more prevalent, the need for a modernized and adaptable control system becomes imperative.
Outdated ATC Equipment:
- The existing ATC equipment, developed in the 1970s, operates on aging principles and components. The technical lifespan of this system has been reached, prompting the industry to seek a more contemporary and sophisticated solution in ERTMS.
Intra- and Interoperability:
- ERTMS offers a harmonized approach to rail traffic management, fostering both intra- and interoperability. This ensures seamless communication and coordination between diverse rail networks, facilitating a more integrated and efficient rail transport system across borders.
Capacity Enhancements:
- Embracing ERTMS brings about significant capacity enhancements. The system’s advanced features enable optimized utilization of rail infrastructure, contributing to a more streamlined and responsive rail network capable of handling increased traffic demands.
Cost Reductions:
- A pivotal consideration in the shift to ERTMS is the potential for cost reductions. The modernized system promises efficiency gains, reduced maintenance expenses, and enhanced resource utilization, all contributing to a more cost-effective rail operation in the long run.
Improved Availability and Punctuality:
- ERTMS introduces a paradigm shift in rail transport reliability. By leveraging advanced technology and real-time data, the system enhances overall availability and punctuality, ensuring a more dependable and predictable rail service for passengers and freight.
History of ERTMS and why it is needed
In December 1989, the European Union initiated a project to address signaling and train control issues. By the end of 1990, the European Institute of Railway Research (ERRI) began developing a common interoperable Automatic Train Protection (ATP) and Automatic Train Control (ATC) system that could be universally adopted across European countries.
This initiative led to the establishment of the European Rail Traffic Management System (ERTMS), also known as ETCS (European Train Control System). A significant milestone was reached as a result of the decision to make ERTMS/ETCS the international command-control and signaling system.
Standardizations achieved through ERTMS have ensured interoperability within the European rail network since the early 21st century. Additionally, from 1996 onward, ERTMS became the sole standard for High-Speed (HS) and High-Capacity (HC) railway lines across many European states, integrating seamlessly with the HS/HC projects and transforming the European railway network into a more efficient and interconnected system.
What is ERTMS, ETCS, and Automatic Train Control (ATC)?
The ATC system represents a technological advancement from Automatic Train Protection (ATP) and is part of the European Train Control System (ETCS) within the European Rail Train Control System (ERTMS). It is designed to protect trains by considering various factors such as rolling stock characteristics, track conditions, speed limits, and signaling details.
Functionality and Constraints of ATC
ATC ensures train safety by continuously providing information on the maximum permissible speed, incorporating factors like track characteristics, train features, and temporary speed restrictions.
It adjusts train speed in case of overruns, utilizing calculations that consider line conditions and train attributes. Precise exchange of information between ground and onboard systems is crucial for real-time speed calculations.
How ETCS works
ERTMS has different levels of train control systems that vary due to the level of advancement of the ETCS sub-system and the types of equipment provided for signal control.
ETCS Basics:
- Ground-based equipment transmits information to or from trains by trackside balises or GSM-R communication.
- This information is processed by an onboard computer in the train to continuously calculate the maximum permitted speed and update movement authority (the allowed distance to travel) based on a continuous calculation of a stopping distance called the braking curve.
ETCS Level 0 and STM level
- does make use of lateral signals, however, relying on trainborne equipment to monitor the maximum speed of a train on non-ETCS routes.
- The train driver remains responsible for observing trackside signals and ensuring safety in operations.
- While lacking some advanced features, Level 0 represents a foundational step towards ERTMS/ETCS adoption.
- STM units are provided to trains, that are ETCS-equipped and operating on lines where the legacy national system must be used. In the case of STM-equipped trains, ETCS serves as a conduit between the national ATP (Automatic Train Protection) and the driver.
ETCS Level 1 (ETCS-1):
- A switchable ETCS balise is provided at each signal
- Eurobalises (standardized European beacons) along the track transmit information about the signal state, speed limit, and track condition to the train.
- While trackside and train communicate in a discontinuous manner, usually through Eurobalises, the onboard computer continuously monitors the maximum allowed speed and computes the braking curve to the point at which the train is authorized to proceed (the end of movement authority).
- Trackside signals may be omitted if a semi-continuous infill is equipped (a semi-continuous infill is when infrastructure data is sent to the train from the Euroloop or the Radio infill unit, giving the train knowledge about its intended course in the future).
- Track detection systems and train integrity checks(checking whether the train wagons are split by accident ) are out of the scope of the ERTMS system
- ETCS Level 1 serves as a cab signaling system, coexisting with existing fixed signal lateral systems. Eurobalise radio beacons transmit Movement Authority and route data to the train, allowing the onboard computer to calculate maximum speed and braking curves.
- This level, known for its interoperable Cab Signalling, is operational on specific lines in Austria, Britain, and Spain.
Illustration of ETCS level 1 as diagram
- In Figure 1, Train 1 receives authorization when passing over balise A at the green signal to run until the end of track section 2. Normally train 1 can travel at the maximum line speed until balise B. If the train has no new information, it should stop before the signal at Balis C.
- Normally train 2 would have left the track section 3 when train 1 passes the green signal at balse B. Hence new authorization is issued to train 1 to continue movement until signal at balis C with the maximum line speed. but if the preceding train hasn’t left, the speed reduction is enforced and train 1 should stop at the stop signal at balis C. When the signal shows yellow the train can move ahead.
ETCS Level 2 (ETCS-2):
- ETCS Level 2 is a digital radio-based signal and train protection system that replaces traditional lateral signals with trainborne displays. Using virtual signals(cab signaling), the system continuously monitors train movements via GSM-R radio communication.
- The Balise information can be transmitted by radio (GSM-R) but Includes Level 1 features. Trains equipped with GSM-R radios can operate on both level 1 and level 2 lines.
- No need for trackside signals, leading to significant installation and maintenance savings. However, few track-side indicator panels are used to indicate overriding or border points.
- Installation of Radio Block Centre (RBC) on land and onboard.
- RBC sends continuous preprocessed information, making traditional signaling unnecessary.
- Through the GSM-R radio network, every train automatically reports its precise location and direction of travel to the RBC (Radio Block Centre) regularly.
- The RBC keeps a close eye on train movements. Along with speed and route data, any movement authority is continuously communicated to the train via GSM-R.
- Track circuits remain active for train detection and integrity verification beyond the scope of ERTMS.
- Eurobalises serve as passive positioning beacons, ensuring accurate train positioning(error checking) between reference points. Between the balises sensors provide location data.
- ETCS Level 2 is currently deployed on Italian High-Speed/High-Capacity lines.
Illustration of ETCS level 2 as diagram
- At ETCS level 2 (see figure below), new movement authority can be issued to the ETCS train to update the authorization to proceed at any time via the GSM-R system
- As Train 2 leaves Section 3, the Radio Block Centre receives this information from systems on the ground (axle counters, track circuits, etc.) and immediately transmits a new authorization to train 1 to allow it to proceed to the end of Section 3.
- In ETCS-1 this new information would not be received until the end of section 2, thereby obliging the train to travel at low speed for a significant part of section 2. At level 2, this information is immediately available, contributing to increased traffic fluidity.
ETCS Level 3 (ETCS-3):
- Represents a full radio-based train spacing system, eliminating the need for fixed track-release signaling devices
- Trains can transmit their exact position through positioning beacons and sensors, enabling more dynamic train spacing calculations based on actual distances between trains.
- Optimizes line capacity and reduces ground equipment.
- Train location and integrity are managed within the scope of the ERTMS system
- This level, known as “moving block,” or absolute braking distance spacing enhances line capacity and is under development, showcasing ERTMS’s evolution towards higher efficiency and sophistication.
- ETCS-3 is still in the experimental testing and research stage but has major long-term benefits in maintenance and operational capacity.
The European Rail Traffic Management System (ERTMS) stands as a game-changer in rail transportation, prioritizing operational compatibility for cross-border traffic. Boasting cost-effective manufacturing, ERTMS encourages competition, making systems more affordable. With heightened safety standards compared to its predecessor, ATC(automatic train control), ERTMS ensures a secure operating environment. It also enhances capacity and speed, optimizing traffic flow and meeting modern rail demands. The system’s cost-efficient operations, from reduced maintenance to resource optimization, underscore its role in shaping a more interconnected, competitive, and technologically advanced future for rail transport.