Switches and their reference points
Description
Current railML 3 data model of a simple switch is missing an attribute to store the switch tangent length. This information is required to calculate the alternative switch reference point.
Background
There are two possible reference points for a switch:
- the switch center point - useful when creating schematic track plans, but exists only "virtual"
- the switch begin - the point, where the branching starts, which is easy to determine outside in the field
Links
- Forum discussion
- Christian Rahmig, 21.02.2022: https://www.railml.org/forum/index.php?t=msg&th=858&start=0&
- Development issues
- Wiki documentation
- IS:switchIS: https://wiki3.railml.org/wiki/IS:switchIS
Proposed solution railML 3.2
The element <switchIS> shall be extended with optional element <locationReference> with attributes @tangentLength given in meters (positive decimal value) and @referencePoint (enum: "switchBegin", "switchCenter").
The new element <locationReference> shall only be provided if the switch is located using a <spotLocation>. If the switch is located with an <areaLocation> ranging from switch begin to its two ends, the switch center point can be calculated as half distance between switch begin and switch end.
Tbd: Is the attribute @tangentLength also needed for crossing elements? No, not needed.