Function DetermineSurfaceAndHighwayType

generator/osm2type.cpp:597–816

}

string DetermineSurfaceAndHighwayType(OsmElement * p)
{
  string surface;
  string smoothness;
  double surfaceGrade = 2;  // default is "normal"
  string highway;
  string trackGrade;

  for (auto const & tag : p->m_tags)
    if (tag.m_key == "surface")
      surface = tag.m_value;
    else if (tag.m_key == "smoothness")
      smoothness = tag.m_value;
    else if (tag.m_key == "surface:grade")  // discouraged, 25k usages as of 2024
      (void)strings::to_double(tag.m_value, surfaceGrade);
    else if (tag.m_key == "tracktype")
      trackGrade = tag.m_value;
    else if (tag.m_key == "highway" && tag.m_value != "ford")
      highway = tag.m_value;
    else if (tag.m_key == "4wd_only" && (tag.m_value == "yes" || tag.m_value == "recommended"))
      return "unpaved_bad";

  // According to https://wiki.openstreetmap.org/wiki/Key:surface
  static base::StringIL pavedSurfaces = {
      "asphalt",       "cobblestone", "chipseal", "concrete", "grass_paver",        "stone", "metal", "paved",
      "paving_stones", "sett",        "brick",    "bricks",   "unhewn_cobblestone", "wood"};

  // All not explicitly listed surface types are considered unpaved good, e.g. "compacted", "fine_gravel".
  static base::StringIL badSurfaces = {"cobblestone",
                                       "dirt",
                                       "earth",
                                       "soil",
                                       "grass",
                                       "gravel",
                                       "ground",
                                       "metal",
                                       "mud",
                                       "rock",
                                       "stone",
                                       "unpaved",
                                       "pebblestone",
                                       "sand",
                                       "sett",
                                       "brick",
                                       "bricks",
                                       "snow",
                                       "stepping_stones",
                                       "unhewn_cobblestone",
                                       "grass_paver",
                                       "wood",
                                       "woodchips"};

  static base::StringIL veryBadSurfaces = {"dirt", "earth", "soil", "grass",           "ground",   "mud",
                                           "rock", "sand",  "snow", "stepping_stones", "woodchips"};

  // surface=tartan/artificial_turf/clay are not used for highways (but for sport pitches etc).

  static base::StringIL veryBadSmoothness = {"very_bad",      "horrible",       "very_horrible",   "impassable",