This is something that was briefly discussed not too long ago and the idea is that a road's speed or class can be modified by the presence of a POI that defines new values for either/both of them. This, hopefully, will make ways that have stuff like traffic signals and crossings, etc. less attractive to route over. The values are specified using mkgmap:road-speed and mkgmap:road-class tags added to the POI. These tags expect an integer value, optionally preceded by a + or - which make the adjustment relative to the original value. For example, mkgmap:road-speed=3 sets the speed to 3 and mkgmap:road-speed=-1 reduces the speed by 1 from whatever value it had before. Here's some possible rules for the points file: highway=traffic_signals { add mkgmap:road-speed = '-1' } highway=crossing { add mkgmap:road-speed = '-1' } highway=mini_roundabout { add mkgmap:road-speed = '1' } The region of the way that has its speed/class modified is limited to the closest points either side of the POI. Not sure if that's the right thing to do yet. Needs playing with. You need to specify the --link-pois-to-ways option to enable this functionality. All feedback welcome. Mark