[GraphHopper] Duration tag

[Andreas Wolf]

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Hi,

Am 05.05.2015 um 12:10 schrieb jean hilda:
> We are testing graphhopper with the CarFlagEncoder. To do so, we
> have created ways with highway=primary and maxspeed value and ways
> with route=ferry and duration tags with value = "hh:mm:ss" (no
> maxspeed for ferry).
> 
> primary ways and ferry routes are connected with nodes belonging to
> each others. With duration tag and no maxspeed tag on ferry
> routes, Graphhopper can't find a route. With no duration tag and
> maxspeed tag on ferry routes, Graphhopper is able to find a route.
> 
> Are we missing something or maybe graphhopper don't work with
> duration tags on ferry route ?

AFAIK, there is no support for durations currently. At least I have
not seen it in the flag encoding, which is where it should normally be.

There are—in my eyes—two ways to add this:

1. add support for durations in addition to speed or
2. use the length of the ferry and the time to calculate a speed

Approach 1 is definitely more work, especially in the routing part (I
have not really dug into that, so I cannot tell you exact steps).
Approach 2 OTOH might be rather inaccurate, as the speed is rounded
with a given precision (I think 5 km/h by default) to save space. With
an additional flag, you could probably turn off this rounding for some
ways (at the expense of lower possible maximum speed, but ferries are
rather slow anyways).

Regards
Andreas

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