|Switch: usage of attribute @course [message #1540]
||Wed, 05 April 2017 12:51
Registered: January 2016
a standard question for railML newcomers is about the connection of
tracks via switches and crossings in order to form a railway network.
Some years ago, we created a Wiki page  for this topic. It became one
of the most called railML wiki pages. However, some questions remained
and I would like to bring the discussion here to the forum in order to
find a final solution for upcoming version 2.4.
A switch is situated in the beginning or the end of a track and may be
connected to other tracks. See the following example:
<trackBegin id="tr01_tb" pos="0">
<connection id="tr01_c01" ref="tr02_c01"/>
<switch id="sw01" pos="0" type="ordinarySwitch">
<connection id="sw01_c01" ref="tr03_c01" orientation="incoming"
The switch begin is located in the beginning of track "tr01". The main
course of the switch is defined by the <connection> in line 4. The
branching course of the switch is defined by the <connection> in line 8.
The attribute @course may have the values "left", "right" and
"straight". However, the choice of this value currently depends on the
orientation of the track where the switch is located. The wiki page 
shows this in four small figures (examples 1-4). Consequently, the same
type of switch (with respect to its construction layout) may define its
branch one time with course="left" and the other time with
course="right" depending on the different orientation of the track where
the switch is located.
I want to ask you if you understand the current implementation /
understanding of railML track connection modelling or whether you
support to change it in the future? Shall the choice of value for
@course depend on the orientation of the track or shall it be
independent and just linked with the construction layout of the switch?
I am looking forward to receiving your comments. The main aspects of the
discussion and the final solution will be tracked with railML Trac
ticket #39 .
 http://wiki.railml.org/index.php?title=Connection_between_tr acks
Christian Rahmig - Infrastructure scheme coordinator
railML.org (Registry of Associations: VR 5750)
Phone Coordinator: +49 173 2714509; railML.org: +49 351 47582911
Altplauen 19h; 01187 Dresden; Germany www.railml.org