[Tagging] Feature Proposal - RFC - 3rd and 4th rail (Michael Reichert)

Joseph Eisenberg joseph.eisenberg at gmail.com
Sun Jun 14 00:26:23 UTC 2020


> there are only 2 networks that I can identify worldwide that are 4th
rail, and I've tagged them both already.

If that's the case, is it worth tagging the distinction between 3rd and 4th
rail systems?

If so, perhaps only the rare 4th rail systems need a new tag, and we can
keep electried=rail for the vast majority of systems which are 3rd rail?

– Joseph Eisenberg

On Sat, Jun 13, 2020 at 9:50 AM Garry Keenor <garry.keenor at gmail.com> wrote:
>
> Paul - thanks for the response. I struggle with the idea that someone
would know that a route is electrified with a ground level contact system,
but not how many rails there are. The possible sources are a) local
knowledge, b) wikipedia and c) aerial imagery. All of these will, 9 times
out of 10, define the system. Also, there are only 2 networks that I can
identify worldwide that are 4th rail, and I've tagged them both already. :-)
>
> best regards,
>
> Garry
>
>
> On Thu, 11 Jun 2020 at 12:49, Paul Allen <pla16021 at gmail.com> wrote:
>>
>> On Thu, 11 Jun 2020 at 08:57, Garry Keenor <garry.keenor at gmail.com>
wrote:
>>>
>>>
>>> Re: using electrified=rail to mean (3rd or 4th rail)
>>> I'm not in favour of this one - railway electrification engineers (of
which I am one) do not consider 4th rail to be a special case of 3rd rail,
but rather a distinct system with its own electrical feeding arrangement.
It would also run the risk of confusion in the mappers mind - they would
read as far as electrified=rail in the tag wiki and miss the later option
for 4th rail. I'm happy to leave electrified=rail to mean 3rd rail if that
is what the group prefers.
>>
>>
>> Using electrified=rail to mean 3 rails and having a sub-tag for 4 rails
is a bad
>> thing.  But perhaps there is a case for retaining electrified=rail to
mean "It's
>> electrified using rails rather than contact line but I don't know how
many rails."
>> You mentioned that contact lines are often visible on aerial imagery.
Mappers
>> may know a route is electrified by other means (such as a newspaper
article
>> saying the route has been electrified) but don't know how many rails
there are,
>> only that there is no sign of a contact line.
>>
>> Argument against it: there may be a contact line but the imagery is too
>> coarse for it to be visible or the mapper doesn't have the skill to
>> interpret the image correctly so uses electrified=rail where it
>> should be electrified=yes.
>>
>> --
>> Paul
>>
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>
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