[Tagging] Public Transport Timetables

Jo winfixit at gmail.com
Wed Nov 7 17:07:17 UTC 2018


(started writing this several hours ago)

The way this proposal is evolving, there will be 2  versions. One that
gives an approximate idea of how much time there is between 2 buses for a
given time of day/day of week. Those can be added as tags on the route
relations.

That one should not be dismissed outright.

And another that goes into full detail, listing all the departures at the
first stop and then lists all stops, with the most common times between
stops as roles. For this we would need separate public_transport=timetable
relations.

I've been trying how that could work and I can confirm what everybody
already knew: it's a lot of work, even for lines that seem relatively
simple at first sight! :-) An incredible time sink.

It is an interesting exercise though and I found some errors in the route
relations while doing it.

One of the shortcuts I took when creating route relations is that I only
mapped the longest variations. An advantage of adding the timetables the
way I'm proposing it, is that the stop sequences of the shorter variations
now also become visible. This may make validation easier to do. When stops
are not in order anymore in a route relation, the validator can detect that.

But it's a lot of data to add and it becomes stale very quickly, plus it's
hard to verify whether it's still OK, or not, even more so than the route
relations for the buses. The only advantage is that they don't
'deteriorate' due to other people mapping. Errors are introduced in route
relations all the time because they are so 'fragile', due to ways getting
split, removed/readded to OSM, but not to the relations, etc.

Anyway, I wanted to make sure that the proposal is as good as can be, but
I'm not convinced that it's maintainable for a larger region either.
Of course, 10 years ago, I was not convinced any small group of volunteers
would be able to create a detailed map of the world.

I think, at present, it's far more important we get to a way of mapping
public transport with a single object (preferably a node next to the
highway) to represent each stop.

Polyglot
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