Talking about surface=ice, how do we handle ice_road=yes? Those roads are common in the Arctic regions and cross frozen lakes, so only accessible in winter. See http://overpass-turbo.eu/s/ls3

In the generic new style map I made those roads unroutable.
https://github.com/ligfietser/mkgmap-style-sheets/blob/master/styles/generic%20new/lines
highway=* & ice_road=yes { addlabel 'ice road' } [0x10002 resolution 24]