[mkgmap-dev] _link roads speed limit needs increasing

Sun Aug 5 13:25:00 BST 2012

The ramps connect a secondary to a trunk. Hence, I'd tag them as 
trunk_link, not secondary_link. That could result in correct routing. 
But in the Bing images, the "dirt track" looks more like a residential, 
which could contribute a
contrary effect.
Since the ramps are very long in that special case, setting a speed 
limit explicitly might also help.
Maybe the Garmin device did not reognize that U-turn correctly, or the 
"penalty" for a U-turn is to small. Which tags are required that a 
U-turn is recognized as a U-turn?
Kind regards,
Bernhard
Am 03.08.2012 02:12, schrieb Peter Hendricks:
> Travelling down highway 32, then 329 in Thailand recently I was told to
> do a U-turn, then use a dirt track, rather than the ramp that linked to
> h'way 329. Try routing yourself in Mapsource or Basecamp at N14 27.106
> E100 32.322. It should look like something in this pic:
> https://dl.dropbox.com/u/30711166/OSM.T.jct.32-329-route.prob.jpg
>
> The route chosen by both GPSr&  Mapsource is actually longer than simply
> following the ramp, but it avoids the ramps.
>
> The ramps were drawn as secondary_link which in the Garmin map becomes
> low-speed ramp with speedlimit 20 and RC=2.
>
> The U-turn is a trunk_link =>  principal h'way, SL=90, RC=4.
>
> The dirt track has SL=20, RC=0.
>
> It looks like the Route Class is less important here than the SL: by
> following the main route you only travel for a short distance over a
> slow road (the track), whereas the ramps are quite long. Mathematically
> this would make for a quicker trip.
>
> To avoid people being routed off main highways I propose that ramps
> mapped from secondary_link get the same SL as secondary and that the
> speed limits on the other links are reviewed.
>
> Regards,
> Peter.
>
>