Line sections

Description

In his forum post, Torben Brand asked for the implementation of line sections within railML. A line section shall be defined as a part of the railway line and a collection of railway tracks. It thus represents some "meso level of detail" in the model of the railway network with lines on macroscopic and tracks on microscopic level.

Background

The line section is an element that is used in some other railway infrastructure models, too. For example, the European format RINF (Railway Infrastructure Register) defines line sections ("Sections of Line") as a part of the (railway) line between adjacent operational points that may consist of several tracks.

In railML, line sections may be introduced in order to have a functional infrastructure representation on mesocopic topology level ("between lines and tracks").

Questions to be solved for implementation:

• What is the (operational) background of a line section? Why is this element important?
• What is the exact dimension of a line section? Where does it begin and where does it end?
• Is it necessary to define a "station" before specifying line section dimensions?
• Shall the <lineSection> have an attribute @type to specify whether the line section belongs to a station ("station") or the path ("path")?
• Is it allowed to have more than one <ocp> in one <lineSection>?
• What is the difference between the (interlocking) related "TVD section" and the (infrastructure) based line section?

Links

• Forum discussion
  • Torben Brand, December 2016: [https://www.railml.org/forum/index.php?t=msg&th=482&start=0&] with feedback from Dirk Bräuer and Christian Rahmig
  • Torben Brand, December 2016: [https://www.railml.org/forum/index.php?t=msg&th=483&start=0&] with feedback from Dirk Bräuer and Christian Rahmig

Proposed solution in railML 3.1

Following first thoughts about a separate element <lineSection> a different solution has been identified in the discussions: hierarchy of <line> elements.

In particular: a <line> element can reference a "parent" line element using the attribute @belongsToParent. Thus, a line can be divided into line sections and a line section can be divided into smaller line sections and so on. The approach is generic.