On Wed, 13 Mar 2019 at 13:29, Andy Townsend <ajt1...@gmail.com> wrote:
> On 13/03/2019 13:18, Paul Allen wrote: > > I've hesitated to ask this question for months now: what's the > > consensus on superroutes? > > In what context are you asking the question? I can think of examples > where the answer would be "a really bad idea" and others where the > answer would be "essential; there's really no other sensible way to have > that data in OSM". > That's more positive than I expected: they're not always on a par with eating babies but the use has to be justifiable. Can I get the data into OSM without a superroute? Sure. Is that data useful without a superroute? Not so much. It is this bus route: https://www.openstreetmap.org/relation/8592409#map=14/52.0860/-4.6644 That is incomplete and has some omissions and errors. I really ought to fix it, but I had this thought about superroutes and realized if I fixed and then found out I could use a superroute I'd later have to rework a few things. It's a circular. It starts at what can loosely be called the bus station. It does what can loosely be called a hairy circular route to return to the bus station. The route then continues on a side trip and eventually returns to the bus station, completing the "circle." There are places where the bus goes into a dead-end and gets out by reversing into a side junction. This differs from similar manoeuvres at a terminus of a non-circular route because passengers are on board. It does a loop-the-loop. It appears to do a figure-8 but actually there are other side-trips that mean it really isn't. One problem that I don't see a solution for in PTV1, PTV2 or "we don't tag it PTV3" is a stop that is ignored on the first pass but comes into play on the second pass. The bus starts at the bus station A, passes through nodes B, C and D and turns right at D to E. On this pass through C it ignores the bus stop there. After it's gone through the alphabet back to A, it again goes through B, C and D but this time turns left to alpha, beta, etc. On this pass it does stop at C. Piling all the stops into the relation may lead the routers to conclude that you can wait at the stop C to get directly to E when you can't (but you can get on at C to take a detour through the greek alphabet and eventually get to E because it's a circular). Splitting it into route segments would fix the problem with the stop at C. On one segment it isn't a listed stop. On another segment it is. Splitting it into route segments would also make it clearer what happens in the loop-the-loop and the figure-of-8 in the town centre, if the splits are chosen judiciously. If I'm really clever I can find splits that make the variant routes fit in nicely, too. You think that route is insane? Wait until I add the variants. Best of all, I could pull these into umap. It would then be possible to display route segments in turn to see where the bus goes rather than trying to puzzle it out from the overall route. Yes, if you're very familiar with OSM you can puzzle it out from the relation, but most people can't do that (and I find it difficult, even with knowledge of how the route runs). So, good idea, bad idea, or should I stick to eating babies as that would be more socially acceptable? -- Paul
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