[talk-ph] Car navigation using Garmin with OSM

maning sambale emmanuel.sambale at gmail.com
Mon Jun 7 06:39:28 BST 2010


Hi,

Again apologies for somewhat off-topic garmin posts.

I have been reviewing estimated time of arrival (ETA) for garmin gps
routing.  I noticed that as Sehested reported, the speed calculation
is over-optimistic.  Due to the absence of complete maxspeed data in
PH streets, I have assigned default speed limits to streets in the
garmin map (not in the osm database).  I followed some of rally and
ianlopez's notes.
http://wiki.openstreetmap.org/wiki/User:Ianlopez1115/Philippine_Tagging

Garminmaps has 8 speed levels:
#  7            No speed limit
#  6            70 mph / 110 kmh
#  5            60 mph / 90 kmh
#  4            50 mph / 80 kmh
#  3            35 mph / 60 kmh
#  2            25 mph / 40 kmh
#  1            15 mph / 20 kmh
#  0            3 mph / 5 kmh

I assigned the speed limits 0-5 to osm-ph roads.  The assigned speed
limits for each highway type are the following:

highway=motorway road_speed=5
highway=motorway_link  road_class=3
highway=trunk road_speed=4
highway=trunk_link road_speed=2
highway=* & motorroad=yes road_speed=4
highway=primary road_speed=4
highway=primary_link  road_speed=1
highway=secondary road_speed=3
highway=secondary_link road_speed=1
highway=tertiary  road_speed=3
highway=tertiary_link road_speed=1
highway=minorroad_speed=2
highway=unclassified  road_speed=2
highway=pedestrian & area!=yes road_speed=0
highway=living_street  road_speed=1
highway=residential road_speed=2
highway=bridleway road_speed=0
highway=byway road_speed=0
highway=service & service=parking_aisle road_speed=1
highway=service road_speed=1
highway=cycleway  road_speed=1
highway=footway road_speed=0
highway=path  road_speed=1
highway=steps  road_speed=0
highway=track road_speed=1
highway=unsurfaced road_speed=1

Another important note is when there is a traffic_signal, speed is
reduced to one level down.  My limited testing showed better time
estimation.  For garmin users, please test some more and report if ETA
calculations are better or needs further improvement.

On Sat, Jan 9, 2010 at 4:27 PM, <riber101-osm at yahoo.com> wrote:
>
> Hi,
> I have now been using OSM to navigate around Metro Manila and a trip to Mindoro and have some experience to share:
> On several occasions Garmin tried to guide me through on way streets going counter flow
> The OSM maps keeps getting better and each time I find a missing oneway info I just add it when I get home, so next time I will get the proper routing. So that should take care of that problem.
>
> Some roads are not connected as having separate ending points
> Guess this is due to the editors we use that doesn't warn about this.
> When funny routings occur I make a note and correct the issue when I get back to the computer.
> So time will solve this as well.
>
> Garmin routing times are overly optimistic as typical speed in Manila is 15 km/h and 20-40 km/h on SLEX
> Garmin often routes through narrow streets rather that using dedicated through fares
> The main reason Garmin is unable to provide better routing is the lack of maxspeed info for most roads.
> I suggest to add the maxspeed info for all roads according to the traffic code RA4136 as follows:
>
> SPEED LIMIT
>
> Passengers
>
> Cars and Motorcycle
>
> Motor trucks and buses
>
> Open country roads, with no "blinds corners" not closely bordered by habitations.
>
> 80 km. per hour
>
> 50 km. per hour
>
> "Through streets" or boulevards, clear of traffic, with no " blind corners," when so designated.
>
> 40 km. per hour
>
> 30 km. per hour
>
> City and municipal streets, with light traffic, when not designated "through streets".
>
> 30 km. per hour
>
> 30 km. per hour
>
> Through crowded streets, approaching intersections at "blind corners," passing school zones, passing other vehicles which are stationery, or for similar dangerous circumstances.
>
> 20 km. per hour
>
> 20 km. per hour
>
>
> Garmin is able to use the maxspeed info to calculate the fastest route and by this automatically select roads with the higher speed limits.
>
> So I will advocate that maxspeed is added to all roads in the Philippines. Until this happens Garmin will keep preferring roads WITHOUT speed limits as is thinks they are the fastest.
> Happy mapping
> Sehested
>
>
>
>
>
> _______________________________________________
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> talk-ph at openstreetmap.org
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>



--
cheers,
maning
------------------------------------------------------
"Freedom is still the most radical idea of all" -N.Branden
wiki: http://esambale.wikispaces.com/
blog: http://epsg4253.wordpress.com/
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