[openrailwaymap] Station importance

[Alexander Matheisen]

On Sa, 2015-04-11 at 09:18 +0200, danmey at web.de wrote:
> this second mail is to think about other ways to determine the 
> importance of a station without any specific tag.
> I have to say that I have no idea about how difficult it is to render a 
> map and define render rules. So throw eggs if these ideas are not really 
> thought through...
> 
> One way to define the importance of a station could be to have a look a 
> the route relations.
> How many different route relations are conected with the stop_positions 
> of the station? Do these relations have a range of service tags (from 
> commuter to long_distance?)
> Perhaps we could define a system to evaluate this.

theoretically this could work, but it needs a lot of calculation.
Especially for rendering this is would require preprocessing of the
data.

But there is also another problem: This would work just for passenger
stations. A tagging solution would also be appliable on non-passenger
stations like freight yards. There are very important freight yards like
Maschen, Seelze, Gremberg, etc., but also freight yards in rural areas
that are just used e.g. for irregular wood or military transports. A
tagging solution would allow us to map their importance too.

> A different way could be the number of platforms: more platforms means 
> higher importance.
> Either with the platform*s*-Tag 
> (http://wiki.openstreetmap.org/wiki/Key:platforms). But it is not in 
> really wide use. I don't use it, either.
> But there could be a way to determine the number of platforms through 
> the stop_area relation.

Same problem for non-passenger stations as describe above.

Also the number of platforms does not indicate the importance of the
station. See this example:

Bonn Hbf
- 5 platform tracks
- DB category 2
- 70 long distance trains per day (according to Wikipedia)
- international traffic with EuroCity trains

Neuss Hbf
- 8 platform tracks
- DB category 2
- just 4 long distance trains per week (3x ICE, 1x IC)
- no international traffic (except from a regional express train that
ends in Venlo, the border station between Germany and the Netherlands)

Zwickau Hbf
- 8 platform tracks
- DB category 3
- no long distance trains
- no international traffic

> Of course, you can show me a lot of examples where a station with few 
> route relations / platforms has higher importance than another station 
> with more of these.
> But as far as I understand the question, the problem is a render problem 
> in cases of  collision. This happens with a small number of stations per 
> case. So, we don't need absolute importance of stations here, but a 
> relative ranking of these few stations.

For collisions, relative importance of the stations would be enough. But
when you want to render e.g. just international stations in low zoom
levels, you need an absolute ranking.


Regards
Alex
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