I am a frequent mapper of railways and I have encountered a problem. A common feature of railways are so called “trap points”. They are usually located at the end of sidings or yards where they merge to the main line, and act as safety by diverting/derailing runaway trains instead of potentially crashing into another train.
Trap points on two sidings outside of Lund, Sweden.
The mapping of these vary greatly, at least in Sweden. I have seen the service tagged as yard, spur and siding. I think that in the case that it is connected to these services, it should be tagged as such. For example, if it connects to a siding, it should be tagged as a siding, or if it connects to a yard, it should be mapped as a yard. Basically the same as how the “service=crossover” tag is used. If it ended there, I would not be writing this post. The problem presents itself with tracks marked as usage, with no service.
Here, also outside Lund, four tracks (all marked usage=main, and rightfully so) become two. The trap points (or the tracks, really) are here marked as “service=spur”. I can’t say that I agree with that mapping, but I also can’t come up with anything better. It isn’t a siding, yard or crossover either. Trains are not even really supposed to use this track at all. It certainly can’t be tagged as “usage=main”.
I have seen on the wiki that these tracks “could perhaps be tagged with service=runaway”, but I wouldn’t start using this blindly (also it does not seem to render properly). Should the switch itself be tagged as “catch points” and in that case, how? I would like some guidance in this matter as I would not want to start changing tags blindly without the community on the same page.
So, should these be tagged as “service=runaway” or something else? Should the points get some tag of their own (like railway=switch, railway:switch=catch or something similar)? I’d like to hear your thoughts!
In Germany, we agreed about ten years ago to use service=yard for those short pieces of runaway track. From signalling point of view, a dispatcher cannot and must not permit train operations into these dead ends (it can be permitted for shunting operations). Their movement authority ends at the signal before the trap point.
And because we see service=* as the key to separate tracks which may be used for shunting only from other tracks, the runaway tracks get tagged service=yard.
As Taginfo indicates, service=runaway is rarely used (24 times worldwide, maybe some of the are not railway features at all). The wording that one could perhaps use service=runaway was added on that wiki page in 2013 when @gormur added the first description. I think that the wording was meant as a suggestion and de-facto tag usage has made this wording being outdated.
I would tag the point as a ´railway=switch` if it looks like an normal switch (having a frog and a short piece of track behind the switch).
I do understand the logic behind this and probably is a good representation in most cases, although certainly not all. I think that service=runaway should at least get its own wikipage, to give it a chance to become the de facto standard tag for this purpouse. I do understand that it would be a lot of work to fully implement.
In those caes service=runaway could be valid because any use of the runaway track by during shunting would be prohibited by the small signal Sh 0 (left track) when the point leads train into the dead end section.
I am also tagging those pieces of tracks as yard. I don’t see anything misleading doing it. Anyone with a minimum of railway operations knowledge will understand at once the purpose of these track set-ups. I don’t see any use case where someone will want to query those ways. Query the derail devices sounds good enough to me.
Also let’s not argue about derail or divert. Some of these tracks are sometime very short (less than 10m) and without buffer stop, any vehicle entering it are likely to derail even if the intent was to divert.
