[Talk-transit] NEW Proposed Feature

Jo winfixit at gmail.com
Wed Feb 2 13:56:46 GMT 2011


2011/2/2 Michał Borsuk <michal.borsuk at gmail.com>:
> On 01/28/2011 02:45 PM, Jo wrote:
>>
>>    Yes that's one option. I'm a bit reluctant to put in separate
>>    relations for each direction unless someone actually gives me a
>>    compelling reason to do so. I already have some ways with more than 20
>>    relations, and I don't really want to double that number without good
>>    reason.
>>
>> http://www.openstreetmap.org/?lat=50.85106&lon=4.75651&zoom=17&layers=M
>> <http://www.openstreetmap.org/?lat=50.85106&lon=4.75651&zoom=17&layers=M>
>>
>> Lijn 7 uses Krijkelberg twice. Bus stop Sint-Kamillus is served by both
>> directions. This can be mapped without ambiguity if there is one
>> relation for each direction.
>
> Do we need such level of details if we can't present it to the user at
> present?

We're mapping for the future. öpnvkarte is not functioning anymore
anyway at present, so the only way of viewing routes is in an editor
like JOSM. What I mean, is that at present we can't present anything
to the user.


>
>> http://www.openstreetmap.org/?lat=50.881607&lon=4.715&zoom=18&layers=M
>> <http://www.openstreetmap.org/?lat=50.881607&lon=4.715&zoom=18&layers=M>
>>
>> Bus station in Leuven. It's perfectly clear where the buses will travel.
>> Not so if both directions are in only one relation.
>
> Is the improvement worth the extra time?

That's something everyone will have to weigh for themselves.

>
>> Sure it would be possible to program something to process a 1 route
>> relation, but it would not be straightforward.
>
> Such situations are quite exceptional. I would know, because I've mapped a
> mixed urban-suburban area, where some lines are the perfect A-to-B straight
> lines, and some are pretty crazy (spoon shape is the least strange of all).

Not all that exceptional, over here it seems to happen in 5-10% of all
bus routes I'm mapping. Buses making loops and spoons, that is.
>
> So: how about "two relations per line are to be optional in cases where one
> relation does not successfully explain the route"?

Sounds fair. Maybe we should have a tag to indicate which approach was used.

paradigm=allinoneroute

or

paradigm=onerouteperdirection

I'm sure someone will come up with better names.

>> Most importantly though,
>> with one route relation per direction, it's a whole lot easier for the
>> mappers to check that the relation is continuous.
>
> At the cost of extra time to enter and maintain, and confusion (it's not how
> it is on printed maps!).

Many things in OSM are not like in printed maps, since a printed map
is only one of the possible goals. For instance people also want to
create drawings of sequences of stops.
>
> I've managed to check continuity with one route, and if you're worried about
> continuity in the aspect of future routing, then it's irrelevant - routing
> software does not follow the route itself, but its bus stops.
>
> I am a die-hard opponent of relation-per-direction, but please convince me
> that it is really worth it.

If the examples I've presented a few days ago can't convince you, I'm
afraid nothing will, so 'I rest my case' :-)

>
>> As far as routes go that have a shorter itinerary during the week, I
>> wouldn't make an extra sets of relations for those. Simply put the
>> longest road traveled in both relations.
>
>
> Sure, that's the way to go, but what is your proposal for routes with
> different paths? I have at least 2 such routes, each has 4 variants. I have
> so far mapped them as one relation, but this is suboptimal. Four relations
> are not much better, and if I were to apply one relation per direction, I'd
> have eight. That's an overkill.

I guess I'm fortunate our PT company assigns a new ref number when
such a situation occurs. This means there are many routes which share
large parts of their paths... So the number of relations doesn't
become less, but since the ref number is different, we don't have
another choice but to create separate relations for these cases.

Cheers,

Jo



More information about the Talk-transit mailing list