Classifies roads by their importance and capacity in the transportation network. Used for filtering traffic data display based on road significance.
Road hierarchy (from highest to lowest):
motorway - High-capacity highways with restricted accesstrunk - Major inter-city roadsprimary - Primary through routessecondary - Secondary through routestertiary - Connecting roads (see TertiaryRoadCategory)street - Local streets (see StreetRoadCategory)
Road hierarchy category type.