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Alex McGrath

B.Eng B.Com CPEng MIRSE

Department of Transport Victoria

The ‘obsolescence problem’ in signalling is a topic of much discussion and consternation. This paper focuses on the different types of obsolescence and the system elements and forces which drive the ‘problem’, to get a deep understanding of the landscape.

Obsolete items are a fact. Obsolescence management is a judgement function, with a predictive element (what is likely to happen), and an evaluative element (what the best course of action is). The obsolescence management standard [1] provides useful guidance – but requires the organisation to define the obsolescence items of interest.

In this paper a nested systems view of obsolescence items is proposed, identifying obsolescence items at three levels:

• Component level obsolescence is managed through established techniques, including life extension, inventory management and component substitution – each appropriate for different types of equipment.
• At the architecture level, the “Grandfather’s Axe” problem emerges, with the interfaces between components themselves identified as obsolescence items. The telecommunications and computer industries provide useful concepts including standardised and layered architectures (e.g. OSI) to respond to this problem.
• Functional obsolescence is when the existing system no longer serves the operational needs of the railway. Re-engineering rail operations is often seen as the response to this, sometimes alongside a transition to onboard technology. These big steps come with their own challenges, especially in safety assurance..