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[mkgmap-dev] STOP signs and routing

From Hendrik Oesterlin hendrikmail2002 at yahoo.de on Mon Sep 20 19:50:54 BST 2010

"Harri" kuuma at bastu.net wrote on 20/09/2010 at 22:22:58 +1100
subject "[mkgmap-dev] STOP signs and routing" :

> On 09/20/2010 01:43 PM, maning sambale wrote:
>> A thread for improving routing gave this suggestion in the points style.
>> highway=traffic_signals { add mkgmap:road-speed = '-2'; add
>> mkgmap:road-speed-min = '1' }
>> highway=crossing { add mkgmap:road-speed = '-1'; add
>> mkgmap:road-speed-min = '1' }
>> highway=stop { add mkgmap:road-speed = '-2'; add mkgmap:road-speed-min = '1' }
>> traffic_calming=* { add mkgmap:road-speed = '-2'; add
>> mkgmap:road-speed-min = '1' }
>> barrier=toll_booth { add mkgmap:road-speed = '-2'; add
>> mkgmap:road-speed-min = '1' }
>> The reduces the road speed of the way with the traffic_signal node.
>> I haven't tested fully but it seems to improve time calculation.

> I have tested it. There seems to be two major problems with that. First
> of all, it lowers the speed of the segment that has the poi. Lenght of
> that segment is sometimes just a few meters, sometimes a long road.

> So, it is more or less based on luck, whether the calculation of time is
> better or not. In any case, the time calculated should be longer. 
> Matters could be improved by for example making an automatic split for a
> road if the segment containing speed-lowering poi gets too long.

This reduces the speed in both directions?

> Another problem is with Garmin routing. I'd be more interested in 
> avoiding the low-speed points. However, Garmin does not use road speed
> too intelligently. Instead it seems to calculate the route based on 
> road_class mostly.

Generally, the maxspeed value seems to be respected.
But I have seen a case where higher speed was applied to the road,
probably the speed of the next road segment.
Maybe it was triggered by some turn of the road.

You can see the effective road speed if you put your Garmin device in
"simulation" mode and route to some POI. 

Hendrik Oesterlin - email hendrikmail2002 at yahoo.de

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