[Routing] generalized routing format

[Marcus Wolschon]

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flo Detig schrieb:
> Robert (Jamie) Munro wrote:
>>
>>
>> For example, you don't want to go all the way around the M25 to
>> get from Dartford to Thurrock, you want to take the A282 over the
>> Dartford Crossing (which links the 2 ends of the almost circular
>> motorway)
>>
http://www.openstreetmap.org/?lat=51.4718&lon=0.2514&zoom=12&layers=B000FTF
>>
> That is an important point! The reason to stay on 'bigger' roads
> (e.g. motorways) is because it's generally faster. Any shortcut
> that is faster despite being on a lower layer network actually
> belongs to the higher layer network. Computing the layers seems
> thus more complicated. Do you think it could suffice to do greedy
> (dijkstra like) searching in all directions, add nodes and edges
> of the desired layer (with travel-time  as cost) and whenever such
> a shortcut appears add it as an additional edge?

I don't think this will be enough for a general format.
It may work for only one application where you limit
yourself to one or two metrices but for a general format
you have to ensure that the data-format works out for
any metric that an application reading this format may
desire.

I think it would be better to discuss basic
storage and indexes first before going on
about special optimizations.

..just my 2ct

Marcus
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