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

Garry Keenor garry.keenor at gmail.com
Sun Jun 14 18:53:18 UTC 2020

I think it is fairly unlikely that any more 4th rail will be built, and
certainly not converted. It is a system which makes it difficult to detect
earth faults, as well as making the design of junctions more complex. Not
impossible though.

best regards,


On Sun, 14 Jun 2020 at 12:22, Paul Allen <pla16021 at gmail.com> wrote:

> On Sat, 13 Jun 2020 at 17:50, 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,
> Or local-ish knowledge.  On-line newspaper article saying the line has
> been electrified (I'm local to me, and I know how to use the internet; the
> newspaper is local to the line).
> b) wikipedia
> Never trust wikiepedia. :)
> and c) aerial imagery.
> Sometimes aerial imagery is crappy.  Good enough to see that there are
> no gantries for carrying an overhead line but not good enough to count
> rails. Unlikely, particularly on a long line, but possible.
>> 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. :-)
> So when 8 more networks are converted to 4th rail, there's a risk that one
> of
> them (using your figures) can't be pinned down. :)
> I assume that more networks will be converted over time, or new ones will
> be built as 4th rail.  Or will they?
> --
> Paul
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