handle surfaces in bike profile

profiles/bicycle.lua

@@ -65,6 +65,24 @@ route_speeds = {
 	["ferry"] = 5
 }
 
+surface_speeds = { 
+	["cobblestone:flattened"] = 10,
+	["paving_stones"] = 10,
+	["compacted"] = 10,
+	["cobblestone"] = 6,
+	["unpaved"] = 6,
+	["fine_gravel"] = 6,
+	["gravel"] = 6,
+	["fine_gravel"] = 6,
+	["pebbelstone"] = 6,
+	["ground"] = 6,
+	["dirt"] = 6,
+	["earth"] = 6,
+	["grass"] = 6,
+	["mud"] = 3,
+	["sand"] = 3	
+}
+
 take_minimum_of_speeds 	= true
 obey_oneway 			= true
 obey_bollards 			= false
@@ -158,6 +176,7 @@ function way_function (way)
 	local service	= way.tags:Find("service")
 	local area = way.tags:Find("area")
 	local foot = way.tags:Find("foot")
+	local surface = way.tags:Find("surface")
 
 	-- name	
 	if "" ~= ref then
@@ -287,6 +306,15 @@ function way_function (way)
 		way.speed = bicycle_speeds["cycleway"]
 	end
     
+    -- surfaces
+    if surface then
+        surface_speed = surface_speeds[surface]
+        if surface_speed then
+            way.speed = math.min(way.speed, surface_speed)
+            way.backward_speed  = math.min(way.backward_speed, surface_speed)
+        end
+    end
+
 	-- maxspeed
 	-- TODO: maxspeed of backward direction
 	if take_minimum_of_speeds then