[Routing] Gosmore routing server - remarks

[Lambertus]

Nic Roets wrote:
>> - Relatively often Gosmore is not able to find a route while looking at
>> the OSM data does not reveal any obvious problems. It would be
> 
> There is a bug in SVN : Gosmore will start and end at the nearest
> segment to the start and end points respectively, even if that segment
> is an administrative boundary. Here is a patch :
> --- gosmoreBadRoute.cpp 2008-05-25 17:50:52.000000000 +0200
> +++ gosmore.cpp 2008-05-28 13:41:56.000000000 +0200
> @@ -392,6 +392,7 @@
>        // We don't do for (int dir = 0; dir < 1; dir++) {
>        // because if our search box is large enough, it will also give us
>        // the other node.
> +      if (!(((wayType*)(data + itr.nd[0]->wayPtr))->bits & (1<<car))) continue;
>        if (itr.nd[0]->other[0] < 0) continue;
>        __int64 lon0 = lon - itr.nd[0]->lon, lat0 = lat - itr.nd[0]->lat,
>                lon1 = lon - (ndBase + itr.nd[0]->other[0])->lon,
> 
> 
I have downloaded the svn version again this morning and performed some 
tests, below are some remarks (more to come probably):

- If one uses 'motorcar' and a cycleway is closest to the 'from' or 'to' 
coordinates then Gosmore seems to select the cycleway and try to route 
from there and failing subsequently because it's a cycleway. Same 
applies to waterways and perhaps areas like 'landuse'? It happens quite 
often that one of these features is besides a road and the current 
behavior requires the user to place their to en from coordinates very exact.

- The wiki page on junction=roundabout [1] explains that the tag 
oneway=yes is not necessary as both the tag 'junction' and the rotation 
direction of the circular way determine the allowed driving direction. 
Gosmore currently calculates a route that cuts the roundabout short when 
the oneway tag is not supplied. Gosmore calculates the route correctly 
on roundabouts with a oneway tag present.

- There's also a roundabout [2] that Gosmore refuses to route over when 
driving to/from the North. I have checked it using Potlatch but can't 
find any problem with the junction.

[1] <http://wiki.openstreetmap.org/index.php/Tag:junction%3Droundabout>
[2] <http://tile.openstreetmap.nl/?zoom=16&lat=53.04656&lon=5.6792>