[talk-au] Mapping railway lines

swanilli swanilli at gmail.com
Wed Oct 7 08:45:05 BST 2009


I can't offer an opinion on Sydney-Melbourne, but I spend a fair bit of time
on trains and have checked the OSM rail data for Sydney-Newcastle,
Sydney-Richmond, Sydney-Katoomba, Sydney-Bomaderry and Sydney-Moss Vale.
This is in metal carriages and except for one occasion, my GPS reported more
than acceptable accuracy (say 6 - 8m) and I concluded that there was no need
to adjust the OSM entries. The problem, as I alluded to in another posting,
is what happens when there are large land features next to the track or
tunnels.

The exception was one trip south when the GPS was unable to get a signal at
any time. Since the carriage was identical to lots of others in which I had
no problem I concluded it must be the metallic coated glass. I have had the
same problem with Victorian VLine carriages.

While I accept that theoretically a large metal box might be a problem, my
own field observations indicate that in practice it need not be. You can
only tell by trying your GPS out in the carriage you travel in.

2009/10/7 John Smith <deltafoxtrot256 at gmail.com>

> 2009/10/7 swanilli <swanilli at gmail.com>:
> > The problem is you will find not with the metal railway carriages but
> with
> > the coating on the windows. I find my GPS works well in almost all
> carriages
> > (I get accuracy typically of 6 m).
>
> The metal box is a large part of the problem, the windows are just
> usually the easiest way to get a signal into the train but if they
> increase the density or add a metalic coating obviously this is going
> to cause problems too.
>
> I've done large sections of NSW and Qld railways from yahoo imagery,
> while not 100% accurate it is the best way we have until some govt
> agency releases data or someone is able to get a trace.
>
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