| [railML3] Use of @next= to link operationalTrainParts into a sequence [message #3993] |
Wed, 06 May 2026 16:27 |
Mike Stallybrass
Messages: 2
Registered: May 2026
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Junior Member |
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I am a long-time railway timetable and real-time operations expert, having worked in the railway industry for over 50 years. Over that time, I have worked on the front-line as a timetabler, as an operations controller and manager, but have also designed and developed a number of timetableing and real-time control systems that are in use around the world today. While the majority of my career has been UK based, I have been seconded to both DB in Germany and Amtrak in the USA, have worked as a consultant for railways in over 25 countries, on every continent except Antartica, and am now (through membership of the UK BSI) participating in CEN and ISO standards development.
I note that railML has an @next= attribute on an operationalTrainPart, which allows them to be linked together into a sequence of train movements. Ultimately, such linkages represent a thread for the deployment of rolling-stock. But in my experience, there are three distinct reasons why, in a passenger railway operational timetable, one train or train-part may be explicitly linked to a following one.
1. As a commercial constraint on later vehicle scheduling, to indicate a commercial requirement for through coaches between trains or train parts, enabling passengers to make a through journey without changing seat. Such constraints are normally created by the train operator during the conceptual development of a timetable. At the time that the constraint is initially created, there may be no information about formations, as no vehicle scheduling will have been done.
2. As an operational constraint on later vehicle scheduling, to indicate an operational requirement for one arrival to become a subsequent departure. Such constraints are commonly imposed for reasons of terminal station capacity, and are normally created by the infrastructure manager during the later stages of development of a conceptual timetable, when the total infrastructure impact of all relevant timetables at a particular location can be considered. I know that such infrastructure capacity driven constraints have been applied at locations such as Charing Cross in London and Hamburg Hauptbahnhof. Again, at the time that the constraint is initially created, there may be no information about formations, as it is unlikely that vehicle scheduling will have been done at that stage of the process by the operator.
3. As a result of vehicle scheduling, to detail the intended sequence of journeys to be performed by the rolling-stock. Such linkages are normally created by the train operator during the vehicle scheduling associated with a timetable. Note that the vehicle scheduling may change the calendar granularity of the timetable, for example if a different train formation is to be used on some days of the week.
Because these three reasons for having an embedded linkage in the timetable have arisen from three very different use cases, would it be sensible to add an additional attribute to indicate if the linkage is there as a pre-vehicle scheduling constraint, and if so, whether it is there for commercial (at seat journey) or operational (capacity) reasons.
[Updated on: Wed, 06 May 2026 19:21] by Moderator Report message to a moderator |
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