[Routing] pre-compute routing and building an ETA-database

[Marcus Wolschon]

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Tim Thornton schrieb:
> Hi
>
> On 9/27/07, *Marcus Wolschon* <marcus at wolschon.biz
> <mailto:marcus at wolschon.biz>> wrote:
>
>
>     You cannot do precomputed routing for 3 simple reasons:
>
>
> Well, you can, but I understand what you're saying. It might work as a
> cache for the common case though, so I wouldn't dismiss it.

Ok, lets think about a cache that can speed up large-scale routing.
For what routing-algorithm and parameters would such a cache be usefull?
It makes little sense to do such a thing for the worldwide net of
secondary roads because that net is too big.
But the network of motorways is so small, that I can
route through it in less time that I need to fetch a URL.
(Besides being usually offline while navigating and re-calculating
 routes while driving.)

>
> I mean if you have more than one type of route, you're just
multiplying the the total dataset size by the number of types.

Sorry, the number is infinite a soon as the user
can input his average speed for each road-type
(Like I can do with every navigation-program and most
 navigation-websites I am using).

> I would be really interested to see if we can build a picture of actual
> average road speed for a given time/day from the data collected so far.
> I'm not sure that we could at the moment, given the emphasis is on
> building a complete map rather than collecting "redundant" points.
> Nonetheless, could make routing ETAs very good. Thoughts?

Collecting average real-world times for segments would be really
usefull data!
Given a service and an API to collect such data I would add a checkbox
for the user to contribute to it right now!
Given user-selected vehicle-class, time of way and boolean
weekdey/weekend such a database could be used to augment ETA-estimates.

Great idea!

Marcus
- --
 Marcus Wolschon
 Wolschon Softwaredesign und Beratung
 UStID: DE238951181
 Marcus at Wolschon.biz
 +49 177/6272871 (m-a-r-c-u-s-1)
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