[Tagging] sidewalks

Peter Wendorff wendorff at uni-paderborn.de
Fri Aug 27 12:33:19 BST 2010


  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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