[talk-au] NSW Transport Data Exchange (TDX)

Michael Gratton mike at vee.net
Tue Jan 22 22:31:40 GMT 2013

On 23/01/13 08:43, Ian Sergeant wrote:
> It raises the age old question, if we can't edit it, why put it in OSM? 
> If each set of data is intended to overwrite the last, what do we do
> when people change it?

Oh, I thought OSM was aiming for an objectively correct map via user
contributions, is there actually anyone arguing for some kind of
libertarian approach to ground truth? ;)

There's no reason why using feeds such as the TDX is incompatible with
individual user editing. From first-hand experience, even the PT
agencies get their data wrong at times, and so the
legion-with-smartphones out there is still actually quite important.

The usefulness of these feeds is two-fold, the first is obviously for
populating a large amount mostly-correct data otherwise missing from
OSM, but equally important is getting updates down the track. Bad data
is after all just as bad as missing data (worse?), as my local
government GIS friend constantly complains.

The challenge then is how to merge feed updates along with
individual-generated changes. It's not impossible, it just requires the
right data, some conventions, some code and a bot.

> It would be nice to see the data integrated with OSM as another "layer",
> however from what Andrew was saying it is only a point to point graph,
> so we can't get OSM style public transport routes from it, only stops.

I don't have any experience with TransXchange or OSM style public
transport, but GTFS does indeed include service routes and timetable
data in addition to stops. The data is there, it just needs a decent


⊨ Michael Gratton, Percept Wrangler.
⚙ <http://mjog.vee.net/>

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