[mkgmap-dev] Questions regarding routing

Fri Jun 7 20:45:05 BST 2013

Hi,

I try to understand the implementation of the code that creates the road net
work.
In 2009 Mark Burton implemented a feature using tags like
mkgmap:road-speed in the points file.
See
http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2009q4/004777.html

Before that Mark also added a feature to handle points with an access tags
like 
"access", "barrier", or "highway".

I think the code for these features is not correct, it sometimes splits
roads into short arcs.

Questions:
1) If a road with road_speed=4 has e.g. 10 points (= OSM nodes) , and the
3rd point has tag
mkgmap:road-speed=-1 and the 8th point has tag mkgmap:road-speed=+1,
what is the expected result?
I would assume that the road is split into 3 parts, one containining points
1-3,
one the points 3-8, and the last one the points 8-10.
The 1st part would use the unchanged road_speed value 4, the 2nd part the 
the value 3 and the last part the value 5.
(if this doesn't introduce any short arcs, else splitting makes no sense for
these tags)
Correct?

2) If a road with 10 points and access=foot has a 3rd point with
barrier=bollard, should this 
cause a split of the road so that points 3-10 have access=bicycle?
I think no. 

3) If a road with 10 points and access=bicycle has a 3rd point with
barrier=cycle_barrier, should this 
cause a split of the road (which just seems to increase the img size) ?
I think no. 

Gerd

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