Interlocking, a plus for interoperability harmonisation

Signalling with outdoors and indoors equipment is a specific asset of the guided railway system. It has traditionally been a national domain embedded in national rules and regulations with high safety requirements. This is currently still the case, despite of the big technological changes which have especially affected the interlocking systems.

As interlockings are not directly located at the interface between track and trains, these very sophisticated and highly safety-relevant devices have not yet been in the central focus for European harmonisation. However there is an increasing awareness that today’s interlockings could become a serious obstacle to the roll-out of ETCS, especially in the radio based configuration.
Based on the findings of the Euro-Interlocking Business Case (project launched by UIC at the beginning of 2000 when the ETCS system with its three levels was in tests), the European railway infrastructure management organisations are spending over EUR 4,000 Million per year on investments and maintenance of interlocking systems for their network. Organisations are also investing a lot of resources for data preparation work, which could be at least partly automated. Implementing a new interlocking is a procedure requiring a large number of steps and processes. The Euro-Interlocking project was conceived to bring a degree of standardisation to at least one of these steps; that of the language in which the railways’ system requirements are expressed. In addition to this, it was planned at the outset of the project that the written requirements would also be modelled, to give a better understanding of their implications. This choice was driven by the indisputable fact that the current state of ambiguity in the European railways’ requirements is a major cost driver in the replacement and modification of interlocking systems. In addition, by delaying the adoption of modelling technologies which are now broadly accepted in other areas of communication and transport, the implementation of ERTMS has perhaps been unnecessarily impeded, because of the difficulty in migrating from an inconsistently documented technology.

Achieving interoperability requires a more efficient standardization

The Euro-Interlocking project, supported by 31 railway infrastructure managers and railway industry companies, is seeking to promote the railways’ use of data preparation tools for the automated configuration interlocking systems for specific sites or zones, also called “specific applications”. Some of the main advantages of data preparation systems for interlocking specific applications are significant cost and time savings for railways in developing and configuring a specific application; more precise specification data that complies with the CENELEC acceptance processes for specific applications.  This also results in less project risks and delays and last but not least, the ability for suppliers to design, configure and implement specific application interlockings more efficiently.
These existing file format standards (Interlocking and Location Data File Format Standards) are now further developed to cover ERTMS/ETCS application. These interlocking and location data exchange formats establish a standardised way to communicate between railways and different suppliers. Benefits of wider adoption can be obtained by all the stakeholders and encourage third party activities in this area. These new standards are intended to be applicable to conventional signalling systems and also to electronics subsystems such as those used in ERTMS/ETCS systems. “Adopting information technology is one way for undertakings to remain competitive. The speed with which they can respond to customers’ demands is crucial in determining the customers’ choice of commercial provider. Use of information technology also allows costs to be reduced”, declared the representatives of the International Rail Transport Committee (CIT).

[ by Elena Ilie ]