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The ARGOS innovation partnership challenge

Computer-controlled interlockings are crucial to ensuring the safety of moving trains by controlling point and signal operations in their catchment area. Many existing interlocking boxes are old or their technologies obsolete and are therefore due for replacement. The ARGOS computer-controlled interlockings under development will enable these electro-mechanical, electrical or purely mechanical systems to be converted and upgraded to digital technology.

The ARGOS project targets high levels of technical and economic performance. By transmitting information in real time, incident response will be swifter, reducing the impact of failures and maintenance and improving traffic flows, with the attendant knock-on benefits for passengers. The solutions developed will obviate the need for intermediate relays, the resulting smaller footprint reducing the volume of ground-based infrastructure and cables and driving down installation and maintenance costs.

The benefits ultimately expected are as follows :

- a 15% decrease in installation and maintenance costs.
- a 30 % decrease in installation lead times: today, medium-sized interlocking boxes take 3 years to be commissioned. With ARGOS, this will be reduced to 2 years.
- improvement in overall performance with the new equipment, in particular with regard to cybersecurity, maintenance and operations.

For Anne-Sophie Naboulet-Larcher, Technological Strategy and Contract Award Manager at SNCF Réseau
 : “Our goal is to roll out an efficient, resilient, easily maintainable system that can be installed and tested with minimum impact on traffic”.

The three contenders emerging from a successful partnership

It was in 2018 that SNCF Réseau embarked on ARGOS, its first multi-awardee partnership. At the end of an 18-month period devoted to research, the development phase now about to begin amply demonstrates the success achieved so far by all the teams involved.

The Thales - ENGIE Solutions - Vossloh group, the company Alstom, and the Hitachi Rail - Eiffage Énergie Systèmes - SYSTRA group have now each been tasked with upgrading an existing installation and developing pre-series production interlockings, the first of which are scheduled for commissioning at end 2023.

A total of 150 experts contributed to the research phase: 35 at SNCF Réseau and 115 at its industrial partners. By deploying such extensive resources, it has been possible to conduct the project to time despite the current health crisis.

For SNCF Réseau, the partnership is a long-term commitment. At the end of the 30-month development period, infrastructure manager and industry will remain bound by a 15-year rollout contract, the purpose of which is to achieve sustainable and durable industrial excellence.


In the spirit of the ARGOS innovation partnership, the Thales-ENGIE Solutions-Vossloh group, which emerged victorious from the competition, is determined to work alongside SNCF Réseau at all stages of the change management process. As group leader, Thales is in charge of project management, system development and delivery. ENGIE Solutions is responsible for research, projects, technical inspections and compliance checks and Vossloh Cogifer for parameterisation, additional and functional tests. The technical solution proposed by Thales won plaudits for its particularly modular and innovative design. In the rollout phase, the Thales-ENGIE Solutions-Vossloh group is to produce a first production interlocking unit for the Auvergne-Rhône-Alpes region, initially focusing more particularly on the Lyon-Vienne corridor.

For SNCF Réseau, the ARGOS project not only targets new system development but is also synonymous with new implementation techniques, based on digital continuity and automation of a number of operations. To achieve this, various innovative tools are to be specially designed for this large-scale project. With the support of its civil engineering consultant SETEC, the Thales-led group has successfully come up with several original proposals with regard to research and rollout that promise to drive down installation lead times by 30%. One of today’s biggest challenges is change management and here the group will be joining forces with SNCF Réseau to maintain the same spirit of partnership that has hallmarked the research period.

“We are proud that the first solution chosen by SNCF Réseau for developing its “high-performance network” is that proposed by the Thales-ENGIE Solutions–Vossloh group for a new generation of computer-controlled interlockings making even greater use of digital technologies. It was 20 years ago that Thales began delivering computerised signalling systems and, over the years, it has built up a strong, trust-based relationship with SNCF Réseau, partnering it in the move towards converting the SNCF network to digital technologies,” Yves Joannic, Vice-President Main Line Signalling, Thales.


The planned evolvement of the interlocking technology has been developed by Alstom as part of the planned transformation of the French rail network infrastructure and the Regional Command Centre program. The new interlocking generation will allow a reduction of 15% of the total cost of ownership for the operator. Through a resilient and performant system, the interlocking will be 30% quicker to deploy than previous generations. While assuring the digital continuity of the product, special focus has been laid on cybersecurity.

Alstoms Smartlock interlocking family benefits from 30 years of worldwide experience. It is suited for all railway topologies with a centralised or distributed architecture and is applicable for both new and existing installations. The technology offers very high reliability and operational functionality, maximising safety and punctuality. Smartlock allows an easy and fast adaptation to future changes in network traffic considerably reducing implementation times in the network. The Montbard installations, spanning 30 kilometers between Paris - Dijon, including the connection to the South-East high-speed line, have been selected as the pilot to enable Alstom to deploy its solution in partnership with SNCF Réseau team from Dijon.

“I am proud that we confirm our leading position in interlocking technology with this project. With railway systems becoming ever more complex, railway operators need a system that they can count on to guarantee the performance and availability of their system. We thank SNCF Réseau for their trust in our innovation management and together to be able to bring interlocking technology to a new standard,” says Jean-Baptiste Eyméoud, President Alstom in France.

(1) contract registered in the 2nd quarter of the current fiscal year


The solution selected by SNCF Réseau and developed by the Hitachi Rail, Eiffage Énergie Systèmes and SYSTRA group is the culmination of the joint efforts of companies that have earned worldwide recognition for their skills in all branches of railway industry and for their substantial local production capacity.

Group leader, Hitachi Rail, is responsible for system development, parameterisation and delivery, Eiffage Énergie Systèmes for work on signalling and SYSTRA for design studies, interlocking study verification, technical inspections and compliance checks.

The new generation interlockings represent a major breakthrough achieved through the best possible technological combination to meet SNCF Réseau’s performance, cost reduction and timeline targets. The technical solution proposed is particularly well-adapted to local or centralised rail network operation. System resilience is enhanced by means of geographical redundancy and cybersecurity considerations built in from the design phase. The approach developed is modular and will lessen the amount of cabling needed, since the system will be able to interface directly with trackside objects such as switches and signals, etc. Its compact enclosures will slot easily into existing SNCF Réseau facilities in the field. Even the methods proposed are innovative, these being based on automation and digital continuity for better quality design processes and interlocking rollout times cut by 30%.
The Hitachi Rail, Eiffage Énergie Systèmes and SYSTRA group will be responsible for preproduction interlockings to control the signal box at Arzwiller and the automatic block signalling section between Réding and Saverne in the Grand Est region.

“The Hitachi Rail, Eiffage Énergie Systèmes and SYSTRA group is highly appreciative of the further display of confidence demonstrated by SNCF Réseau through the award of this ARGOS contract. The two years that we have spent working with SNCF Réseau and its engineers in this innovation partnership and the long-standing relations between SNCF Réseau and the members of our group have enabled us to pool our experience and tap into a wide range of skills in jointly developing the specifications and architecture for the new generation signal interlockings.

The contract that has been awarded is a tribute to the skills and efforts of the men and women who played a part in ensuring the success of the first part of the project and will enable us to further pursue our work on designing and developing the innovative solutions crucial to transforming tomorrow’s railway infrastructure,” Gilles Pascault – Chairman of the Board of Hitachi Rail STS France.

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