R: [mkgmap-dev] road_speed parameter

Wed May 27 15:04:29 BST 2009

This is what I know:

Road_speed: 0 to 7

Default values: 7=128Km/h, 6=108Km/h, 5=93km/h, 4=72km/h, 3=56km/h, 2=40km/h, 1=20km/h, 0=8km/h. In Mapsource you can change speeds for levels 2 to 6. My garmin nuvi 255 does not allow any change respect the default speeds. I don't know about other devices.

The speed is used for route calculation (shorter time). But for best route calculation, garmin gives also a time penalty to each turn you are required to do in a given route.

Road_class: 0 to 4

cGPSmapper says it is the main driver for the route calculation (but does't explain how it is used. maybe is also used to decide if a cross is a turn for you or you are just proceeding on the main road... I don't now but I'll made some experiments

Ciao.

--- Mer 27/5/09, gypakk at gmx.eu <gypakk at gmx.eu> ha scritto:

> Da: gypakk at gmx.eu <gypakk at gmx.eu>
> Oggetto: [mkgmap-dev] road_speed parameter
> A: "Development list for mkgmap" <mkgmap-dev at lists.mkgmap.org.uk>
> Data: Mercoledì 27 maggio 2009, 14:43
> Somewhere in style files there are
> road_speed parameters.
> Today I know that the speeds for 5 different road classes
> can be set in Mapsource.
> 
> I assume that the road_speed values in style file represent
> these 5 Garmin road classes. But how does the GPS device
> know what speed is referred to by what road class? Is there
> a speed table in gmapsupp.img file?
> 
> How can I change these speed values for the GPS device?
> 
> Since these speeds are surely used by the routing algorithm
> to weight alternative routes, I would like to get influence
> on that, especially for preferring cycleways and residential
> streets for cyclists.
> 
> Markus
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