How are roads classified as 'Urban' or 'Rural'

[basimexe]

Hi,
I'm currently OSRM's car profile referring to #6002 I understand the precedence of speed. There is a road in Denmark whose tags should be:

• highway=unclassified
• maxspeed=80
• surface=asphalt

I have set the speed of unclassified type to 72, but as this road is in a rural area, I have set max speed of rural as 50 in:

maxspeed_table_default = {
      urban = 50,
      rural = 50,
      trunk = 110,
      motorway = 130
    },

• Calculating the speed between two points on the said road I get 72.
• I don't understand how OSRM is classifying a road as Urban or Rural. If the said road is in a rural area shouldn't the speed be overridden by 50?
• How does Wayhandlers.maxspeed actually work?

[ftrebien]

In car.lua, maxspeed_table hints that OSRM uses source:maxspeed somehow. car.lua defines that WayHandlers.speed (which infers the speed from the way type) runs before WayHandlers.maxspeed (which should then override it if a maxspeed tag is present). WayHandlers.maxspeed defines that source:maxspeed will be used if maxspeed is not set on the way. This in turn calls WayHandlers.parse_maxspeed which uses maxspeed_table_default with the urban/rural/trunk/motorway suffix of source:maxspeed values.

So if your way has neither maxspeed nor source:maxspeed, the inferred speed is the one related to the way type. If it has only source:maxspeed, then it is inferred from the urban/rural type it specifies. If it has both maxspeed and source:maxspeed, maxspeed should be used.

[basimexe]

Perfect, it makes sense now.
Thanks.