Definition of speed section not sufficient for ETCS description

In ETCS a speed section is specified together with the variable Q_FRONT. This variable is defined as below:

Click to expand

image

In railML 3.3 beta2 the speed section contains an attribute called trainRelation that is meant to model this ETCS variable. However it seems that the definition vary. The ETCS definition is focused on the exit of the section, while the railML definition is focused on the entry. This may get solved by changing the documentation, but it is very likely that the necessary documentation will be very complex and hard to understand, especially for people from the ETCS world. To make matters worse the enumeration that is used to define this in railML is also used in timetable to indicate the alignment of a train with a stopping place.

I would propose the following to improve the situation:

Separate the two enumerations. Use the existing one in timetable only as only timetable

For the IS part we have two options:

Click to expand

Change the documentation: Describe that if the new speed is less restrictive than the last then it can be used to indicate that the train needs to enter the section fully before taking advantage of the less restrictive speed limit. If the speed limit is more restrictive no matter what is given it still means that the speed applies as soon as the front of the train enters.

or

change the modelling: rename the attribute to endPointValidity and have it refer to an enumeration that has values trainLengthDelay and noTrainLengthDelay, terms that are coined in ETCS and easily understood in the railway domain.

I modelled the latter in the branch: ALL.Siemens.Feedback.3.3beta2.Q_FRONT

Links

Edited by CO Onto

railML.org e.V. (Registry of Associations: VR 5750) Phone: +49 351 47582911 Altplauen 19h; 01187 Dresden; Germany