[Talk-GB] railway=rail + oneway?

[Mark Goodge]

On 15/01/2021 10:41, David Woolley wrote:
> 
> I think you are taking a general public consumer view of the map. The 
> main value of maps is often for planners, and researchers, not for 
> travellers.
> 
> Whilst rail planners will already have more detailed maps, and other 
> planners might occasionally benefit from the information, but the other 
> big factor is that a great deal of information goes on OSM because 
> people are enthusiastic about particular subjects, for which maps may 
> exist, but are not generally published, e.g. people collect information 
> on sewers networks.

Where are we going to get the information from, though? It's not 
something you can reliably tell just by looking at the track. And even 
where you can tell, the track often isn't accessible to the general 
public. So it's not amenable to on-the-ground mapping.

On the other hand, unlike a road dual carriageway, you can't assume that 
a double track railway line is a matched pair of single-direction 
routes, because there are a lot of places where it isn't. So it's not 
amenable to armchair mapping either - there's no way at all to infer the 
data from the aerial imagery.

The only reliable, complete source of such information is Network Rail's 
own data. But unless that's published under a compatible licence, we 
can't derive data from it.

So all we're left with is a few, isolated instances where someone with 
the relevant local knowledge updates the map. But that's not 
sustainable, or even particularly useful. And some of the examples 
mentioned by Dave F at the start of this thread are clearly erroneous - 
it's logically impossible for a terminus track to be one-way.

So, while this might be something that some rail enthusiasts might like 
to put into OSM, I really don't think that OSM is an appropriate 
repository for it.

Mark