Expert-Partners for Safer Rails // ZÖLLNER & SYSTRA

Innovative Track Warning System for ETCS Level 2 lines

The Need for a New System

In France, the most common method for warning work crews of approaching trains remains the use of lookouts. At the same time, the deployment of Automatic Track Warning Systems is becoming more frequent (especially for certain works such as track renewals).

With growing investment in regeneration projects, maintaining train traffic alongside construction zones is becoming standard, prompting broader deployment of automatic warning systems. ATWS systems can reduce labor needs but require an individual case study for the installation of train detectors for every system installed.

The core track network is being equipped with ERTMS digital signalling and the idea was to take advantage thereof in order to develop a system that complies with SECUFER regulations while keeping installation efforts and costs low.

 

The Requirements for the New System


Based on the context above, the development of a new automatic announcement system was to meet the following goals:

  • Enable automatic train movement announcements across the entire equipped line, regardless of location.
  • Avoid any modifications to existing signaling stations and systems, as well as any new cabling in rural areas, to prevent major additional costs.
  • Be adaptable to any line equipped with ERTMS Level 2, or to stations that integrate data exchange systems with ERTMS RBCs.
  • Comply with EN 16704 standards

To allow a flexible use of the system, three different operating modes were defined:

  • Mode 1: Warning for traffic on the adjacent track only, at maximum operating speed, for off-track work near the Danger Zone (ZD as defined by RFN regulations). This mode also allows entering the ZD if doing so on other tracks is not possible.
  • Mode 2: Warning for traffic on the adjacent track(s) at operating speed for work on a single intercepted track (same functionality as DALGV).
  • Mode 3: Warning for traffic on all tracks at operating speed for short-duration in-track work using non-fixed light tools.

The SYSTRA–ZÖLLNER Partnership

In order to develop a system that meets the above-listed requirements, the project was split according to the expertise of the two companies. The division looked as follows:

SYSTRA is responsible for system integration, from collecting data for configuring announcement equations to on-site functional testing and validating platform settings.

ZÖLLNER handles the industrial development of products in compliance with CENELEC standards, including component certification.

A Quick Side Note: What exactly is ERTMS?

ERTMS (European Rail Traffic Management System) is a standardized train control and command system developed by the European Union to

It consists of two main components:

ETCS (European Train Control System), a train protection system that

  • continuously monitors train speed and movement, replaces national automatic train protection (ATP) systems with a unified standard,
  • ensures trains operate within safe speed limits and braking distances.

GSM-R (Global System for Mobile Communications – Railway), a radio communication system based on GSM technology which

  • enables secure and reliable voice and data communication between trains and control centers.

 

Key Objectives of ERTMS

  • Interoperability: Allow trains to run across borders without changing signaling systems.
  • Safety: Prevent accidents through continuous speed supervision and automatic braking.
  • Efficiency: Increase line capacity and reduce delays.
  • Cost Reduction: Lower infrastructure and maintenance costs over time.

Testing at the La Virvée Worksite

Near Bordeaux, the LGV SEA (Sud Europe Atlantique) line connecting Tours and Bordeaux crosses the compressible area of the La Virvée marsh using a succession of engineered structures, before reaching the viaduct over the Dordogne River. Structure RBT 2952 is 406 meters long and has suffered significant settlement issues since its construction. A resin injection solution was chosen for repairs. These repairs are carried out from the railway platform and require night-time Temporary Traffic Interruptions (ITCs). Due to the site’s proximity to Bordeaux, ITC timing is offset between Track 1 and Track 2, both at the beginning of the night and during the morning handover.

Due to the significant offset between the ITC zones on Track 1 and Track 2, and the need to accelerate work progress given the high volume of injections, SYSTRA and ZÖLLNER proposed deploying their automatic Warning system. This solution enabled maintenance activities to continue on one track under ITC while allowing commercial train traffic to operate on the adjacent track.

As the system was still in a prototype phase (the formal safety certification still outstanding)—with most applications likely requiring SIL3 compliance—the time between the warning and the train passing the work zone was extended. This adjustment ensured that workers could safely rely on local safety switches installed at the worksite.

 

 

In practice, the sequence of events looked like this:

  1. The worksite is active, with one track placed under ITC (Track Occupancy Control) and the adjacent track designated as the "announced" track.
  2. Protection switches for the announced track are activated and set to "red."
  3. As a train enters the announcement zone, it triggers the warning system (with the unmistakable and clearly audible signal as well as flashing blue lights).
  4. The ASP (Personnel Safety Agent) clears the Danger Zone (ZD) on the announced track and verifies that all activities on the ITC track comply with safety requirements for a train passing on the neighboring line.
  5. The ASP then deactivates the protection switches, switching them to "green."
  6. Once the train has passed and the announcement ends—accounting for the possibility of a following train—the ASP reactivates the protection switches (back to "red") and authorizes the workers to re-enter the Danger Zone.

How it works

What comes Next?

The system has been in active operation on-site since November 2023.
Notably, the innovative components, though based on an experimental setup, have performed flawlessly throughout this period.

The next phase involves the development of new components in accordance with CENELEC standards, aiming to achieve a Safety Integrity Level (SIL) that aligns with operational and user requirements.

The system’s overall effectiveness has been clearly demonstrated. The previously outlined benefits are tangible, and a wider deployment—particularly on lines equipped with ERTMS Level 2 or managed by control centers with ERTMS interfaces—would enable rapid and efficient implementation.

About our partner SYSTRA

SYSTRA is one of the world's leading engineering and consultancy groups specialising in public transport and mobility solutions. For 65 years, the Group has been committed to helping cities and territories to contribute to their development by creating, improving, and modernising their transport infrastructures. With its 8,250 employees, the Group's mission is to make travel more fluid throughout the world in order to bring populations closer together and facilitate access to employment, education and leisure. Signature team for transportsolutions, SYSTRA supports its partners and clients throughout the lifecycle of their projects.
www.systra.com

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