Hi.
On 27.08.2010 11:36, Nathan Edgars II wrote:
One would think that a router would be able to prefer a parallel
footway without a special tag.
+1
One real problem with routing along
sidewalks is that they sometimes don't have curb cuts at
intersections, yet it's legal to cross there. Example:
http://maps.google.com/maps?ll=28.457321,-81.45624&spn=0.000993,0.002575&t=k&z=20&layer=c&cbll=28.457407,-81.45623&panoid=W8rLGRkFUgFWzRRpWLSWCg&cbp=12,59.26,,0,10.44
To route correctly here, you'd either have to draw an incorrect
footway, or the router would need to be able to "jump" a gap if
there's no barrier (and you don't tell it you're in a wheelchair).
Hmm... Where there are strips of grass between street and sidewalk I
didn't draw a crossing yet, as usually there is a more secure crossing a
few meters away (e.g. traffic signals or zebra crossing).
In Germany I think there would be a crossing somewhere on the next
kilometer aside - and to get the most secure route it should be advised
to use that.
To make clear:
using crossings only is not a must - that's right.
But often the most secure route is required - for blind people or even
for children. To fit this requirement an application should be able to
decide where a crossing is most secure,
Impossible, where not given in the data.
If the router has to guess crossings, there will even be routes across
big streets outside of cities.
In any case:
- it's not possible to guess reliable for crossings by software without
support from the data
- it's not a good option to ignore tagged crossings.
regards
Peter
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