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Working groups for ERTMS specification are currently in the midst of the program's "consolidation phase." Their objective is to reissue a consistent set of specifications by the end of 2004. The consolidation phase is clearly a period for correcting the errors of past specifications. Their base reference is the currently published set of documents as they appear in the Technical Specification for Interoperability (TSI, May 2002). Modifications are being made to those specifications by UNISIG and the ERTMS EEIG User Group to ensure consistency. It is expected that the end of the consolidation phase will generate a new release of the TSI, and most notably a new SRS version 3.0.0.
Probable new functions
There will probably be further functional modifications requested after consolidation. Several major functions come to mind, such as Level 1 limited supervision (as promoted by the Swiss SBB), as well as Level 3, which has been postponed until now. As time passes, we may also conclude that some of today's national functions should indeed be shared and integrated into the common core.
In more than one instance, separate countries are adding functions to the core of ERTMS for their own operations, but each one is doing it in its own way leading to multiple implementation of the same function. It is reasonable to expect from both the industry and the railways that those common functions be included in the core of the standard.
Although we know the specification will change again, some amount of stability will be required in the specification releases so that actual implementation and deployment can be realistic.
The need for this stability has been raised by all parties: - Railway infrastructure owners and operators, who will have to manage various versions of ERTMS.
- Industry members, who need time to specify, develop and prove continued interoperability.
As leading members of the rail industry, we strongly believe that such a process is already highly intertwined and that putting several of those processes in parallel would lead to unstable and confusing situations. Baselines must be put in series.
Version management a "must" for the new specification
ALSTOM believes that this "version management" must be discussed with all involved parties to come up with a sensible and realistic road map. We also think that version management should be specified in the next TSI release in order to be prepared for the future. Many contracts have already been placed and most refer to the TSI dated May 2002. A strong effort from UNISIG is underway to ensure that the consolidated version of the TSI to be issued beginning of 2005 will be backward compatible with the existing one, but there is not yet any certainty that this will be the case.
ALSTOM, as a system provider and an ERTMS leader, is trying to anticipate potential problems. We are raising issues. For example, we have offered possible solutions for car-borne flexibility concerns. We now are hoping to have railway industry feedback on these issues so that together, we can influence the specification to the best ends.
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ALSTOM's suggestions for improving ERTMS specifications
- Take into account a 4-year lead-time between baselines to ensure that changes will be rock-solid
- Require that each baseline come with a migration plan in order to help infrastructure owners and to facilitate switching from one baseline to the next.
- Extend the TSI to include a mechanism allowing car-borne equipment to host several versions of ERTMS/ETCS so that it can cope with various track sides.
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