Different modelling of electrification systems in RS and IS

Links

• Forum discussion:
  • Christian Rahmig, 24.05.2024: https://www.railml.org/forum/index.php?t=msg&goto=3247&#msg_3247

Summary

There are currently different ways to model electrification properties in IS and RS. While IS refers to electrification systems defined in CO by id and provides additional attributes, RS elements derive from the ElectrificationSystem type in CO and provide other additional attributes. This leads to unnecessary schema dependencies, and potential trouble matching values from IS with values from RS.

Details

CO:electrificationSystems works as a list of CO:electrificationSystems that can be referenced elsewhere. The model of an electrification system is very simple, with just two attributes:

• @voltage: electrification system voltage, in [V]
• @frequency: electrification system frequency, in [Hz]

IS:electrificationSection refers to the listed electrification systems through its subelement electrificationSystemRef. Additionally, it allows specifying properties of the contact interface between the infrastructure and the rolling stock, and requirements for the rolling stock used. I've listed the relevant properties below:

• @contactLineType: type of the installed contact line ("3rdRailBottom", "3rdRailSide", "3rdRailTop", "none", "overhead", "sideRail" or other:*)
• electrificationSystemRef: reference to a CO:ElectrificationSystem
• energyCatenary: catenary energy parameters (@allowsRegenerativeBraking, maxTrainCurrent)
• energyPantograph: pantograph energy parameters (@requiresTSIcompliance, @compliantTSITypes, @nationalPanHeadTypes, @contactStripMaterials)
• energyRollingstock: rollingstock energy parameters (@requiresPowerLimitation, @permittedStaticContactForce, @permittedMaxContactForce, @requiresAutomaticDroppingDevice, @requiredFireCategory)
• pantographSpacing: pantograph spacing parameters (@numberPantographsRaised, @spacingPantographsRaised, @speed4PantographSpacing)

RS:engine (subelement of RS:vehicle) and RS:trainEngine (subelement of RS:formation) do not reference the electrification systems listed in Common. Instead, they have differently named but identical subelements (powerMode and tractionMode, respectively), both of type TractionMode, which in turn is just an extension of ElectrificationSystem with two more attributes:

• @mode: Mode of traction related to the ElectrificationSystem ("battery", "diesel", "electricOverheadLine", "electricThirdRail", "hydrogenFuelCell" or other:*)
• @isPrimaryMode: whether this is the primary mode of traction of the train

The issue

1. The type TractionMode (used by RS:engine/powerMode and RS:trainEngine/tractionMode) conflates two possibly incompatible things: electrification system properties and traction mode (which may be non-electric, in which case the current documentation says that the electrification properties should be explicitly set to 0).
2. IS:electrificationSection@contactLineType and RS:engine/powerMode/@mode have overlapping value sets, but use different values for the same concepts:
   • "electricThirdRail" in RS is either "3rdRailBottom", "3rdRailSide", "3rdRailTop" or "sideRail"(?) in IS
   • "electricOverheadLine" in RS is "overhead" in IS
3. There are no properties in RS to match against most of the rolling stock requirements given by IS:electrificationSection. This means that we can cover the use case of listing the requirements, e.g. in a Network Statement, but we cannot cover a use case of mapping where given rolling stock can be used.
4. The derivation from ElectrificationSystem in RS (via TractionMode) leads to an unnecessary dependency on CO.

Possible solution

1. Move TractionMode from CO to RS.
2. Remove ElectrificationSystem as base for TractionMode and add an electrificationSystemRef.
3. Add an attribute to ElectrificationSystem specifying the type of electrical interface between the infrastructure and rolling stock to replace IS:electrificationSection@contactLineType and parts of RS:engine/powerMode/@mode and RS:trainEngine/tractionMode/@mode.
4. Deprecate IS:electrificationSection@contactLineType.
5. Replace "electricOverheadLine" and "electricThirdRail" with one common value in TractionMode/@mode
6. Should we add more properties to RS to match the requirements specified in IS, or is there no demand for this?
7. Clean up subelements of IS:electrificationSection (see #512)

Solution discussed in modelling telco 29.04.2024

Separation between tasks for RS and IS based on discussion in the meeting.

In RS

• Agreed
  1. Move TractionMode from CO to RS.
  2. Remove ElectrificationSystem as base for TractionMode and add an electrificationSystemRef.
• Needs discussion/alignment
  1. Replace "electricOverheadLine" and "electricThirdRail" with one common value in TractionMode/@mode
  2. Should we add more properties to RS to match the requirements specified in IS, or is there no demand for this?

In IS

1. Add an attribute to ElectrificationSystem specifying the type of electrical interface between the infrastructure and rolling stock to replace IS:electrificationSection@contactLineType and parts of RS:engine/powerMode/@mode and RS:trainEngine/tractionMode/@mode.
2. Deprecate IS:electrificationSection@contactLineType.
3. Clean up subelements of IS:electrificationSection (see #512)