Interlocking project gets its modelling software

Statemate Magnum, from I-Logix, with model checking capability developed by OSC, has been chosen by the Euro-Interlocking project, putting it at the heart of development in the European rail industry

I-Logix and Offis Systems and Consulting (OSC) have joined the Euro-Interlocking project as industry partners to provide crucial system development technology to help standardise the functionality and interfaces for future European railway points, switching and signalling systems.

Euro-Interlocking's project tasks and deliverables have been prioritised so that railways can begin procuring their Initial Projects, which will determine where the Euro-Interlocking Standards can first be implemented on their networks, as early as 2002.

To support their collaboration, both I-Logix and OSC, the German-based embedded systems specialist, will be donating technical backup consultancy services to the core team on an ongoing basis to ensure the project meets its challenging deadlines.

Functional models of the interlockings developed with I-Logix' Statemate Magnum graphical modelling language will be the common communication language among Euro-Interlocking, the national rail companies and the rail equipment manufacturers.

Statemate Magnum, with its model checking capability developed by OSC, has been chosen by Euro-Interlocking to provide a common medium for capturing the rail companies' interlocking requirements, developing executable functional models and communicating these models back to the rail companies for validation.

Statemate Magnum does this through visual models which improve the comprehensibility of written specifications and can be used in conjunction with the model checking capability to validate mathematically that the behaviour of the models matches the functional requirement.

Formal validation of functioning models is required to ensure final interlockings meet Europe's CENELEC safety criteria.

Statemate Magnum's model checking leaves nothing to chance by checking hundreds of combinations of sequences would be hard to check by conventional simulation.

The Euro-Interlocking Project began in 1999 with a core project team based in Zurich, Switzerland.

It aims to create a common European standard for interlockings, ensure safety properties fully comply with European CENELEC criteria and significantly reduce the life-cycle costs.

Its goal is combining the different interlocking requirements from the participating rail companies and putting them into a common framework; each country currently has its own standards for interlockings, making it difficult for new suppliers to enter the market and hard to enable cross-border procurement.

Crispin de Courcey-Bayley, Euro-Interlocking's Business Manager, says: "Ambiguous requirements have long been seen as a major cause of problems in the design phase of interlocking systems.

"The dynamic functionality of the system is especially hard to describe comprehensively when merely using verbal statements.

"Reviewing engineers need a more concrete vision of the system to do this properly and in order to validate functional requirements, a functioning model is a necessity.

"We understand that Statemate Magnum gives us precisely what we need to effectively capture all functional requirements and to provide the formal verification technology needed to validate that safety properties meet CENELEC standards".

Statemate Magnum models of track elements are hidden so that the reviewer can only test them through test panels, an approach which will ensure the chosen modelling structure will not influence the reviewing work as the internal architecture is not visible.

Reviewers have to check the functionality of a track element by testing the response to certain triggering events, and this functionality should be the same as that described in the textual requirements.

By observing the changes of internal states and the outputs of the modelled interlocking systems according to selected inputs values, the reviewer can validate the system and submit change proposals based on any national differences in requirements.

Gene Robinson, President and CEO of I-Logix, and Dr Werner Damm, co-founder of OSC and Vice President of its Embedded Systems Division, said in a joint statement: "Euro-Interlocking's decision to make Statemate Magnum a central platform for capturing and communicating the project requirements puts it at the heart of development activities within the European rail industry.

"However, in addition to it being a vital tool for all the consortium members, it will also be a primary method by which requirements will be communicated to potential equipment manufacturers for procurement purposes.

"Our collaboration effectively catalyses our goal of making Statemate Magnum a defacto standard in the European rail industry".

(Updated by CR, May 2007).

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