| Re: suggestion for switchIS@type="crossingPart" [message #3922 is a reply to message #3846] |
Sun, 08 March 2026 08:14   |
christian.rahmig
Messages: 580
Registered: January 2016
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Senior Member |
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Dear all,
the topic of modelling simple crossings in a way of unambiguous layouting has been discussed in the SCTP working group and in the BaneNOR workshop, too. As shown in the presentation [1], we could solve the question of unambiguous layouting for single switch crossing and double switch crossing. However, the situation with simple crossings remained open:
The following model of a crossing (see slide 17) still results in two possible layouts:
<crossing id="cro42" angle="140">
<name name="69K08" />
<spotLocation id="swi42_sloc01" netElementRef="ne_15" ... />
<straightBranch netRelationRef="nr_a15a18" radius="0" />
<straightBranch netRelationRef="nr_a16a17" radius="0" />
</crossing>
Question to be answered in this example: what is the reference for the angle attribute? Solution proposal: we define a semantic rule that a simple crossing always needs to be located on the topology (netElement) using a <spotLocation> element. This means that the simple crossing will be located at exactly one of four <netElement> elements connected in this crossing. This one <netElement> can be the reference as "incoming branch" from which the angle of the crossing branch can be added in a mathematical positive direction with values in range 1..179. For above example referring to slide 17 of the presentation [1] this means that the layout of the crossing will be one of the two lower options.
For solving the last step, looking at the navigable <netRelation> elements is necessary. For example:
<netRelations>
<netRelation id="nr_a15a16" navigability="Both" positionOnA="1" positionOnB="1">
<elementA ref="ne_15" />
<elementB ref="ne_16" />
</netRelation>
</netRelations>
In this example the connection from "ne_15" to "ne_16" is navigable. Together with the information about the crossing angle as described above, we end up with an unambiguous layout of the simple crossing. Do you agree?
[1] https://cloud.railml.org/s/XpJHA6HSNPTZfy4
Best regards
Christian
Christian Rahmig – Infrastructure scheme coordinator
railML.org (Registry of Associations: VR 5750)
Altplauen 19h; 01187 Dresden; Germany www.railML.org
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