HERE Map Content Developer's Guide

Functional Class

Definition

Functional Class defines a hierarchical network used to determine a logical and efficient route.

Usage

Functional Class can be used to determine sets of roads that form connected graphs.

Specification

General

An arterial network is connected. Each road has at least one connection in the network to every other road with the same Functional Class via a road with the same or higher functionality.

  • Roads with Functional Class = 5 also receive Low Mobility = 1.

  • As a general rule, Functional Class assignments have no direct correlation with other road attributes like Speed Limit, Controlled Access, Route Type, etc. While in general Functional Class = 1 roads are controlled access this is not always the case, and it is also not the case that all controlled access roads are Functional Class = 1.

  • The Functional Class network is a hierarchical classification of roads based on reality. Density and pattern of each Functional Class level is influenced by the physical road network that exists in reality. Physical road network density variations between countries and between regions within a country are reflected in the Functional Class network. For example, the density of the road network differs between North American and European countries. Even within the U.S., for instance, density varies from the East Coast to the West Coast.

  • Functional Class = 1, 2, 3, and 4 roads are connected to form a comprehensive road network for navigation of long distance, mid-range and short routes in any given coverage area.

  • For example, long distance routes are often calculated by searching the road network through progressively higher Functional Class to get to a Level 1 road. The route continues exclusively on Level 1 roads until travel is required through progressively lower Functional Class in order to reach the destination.

  • If two or more roads with different Functional Class values connect, the lower Functional Class value is applied for the connecting roads.

  • If a road's Functional Class is the same on both sides of an intersection, then the road segments internal to the intersection receive the same value.

  • Road segments on a roundabout receive the highest Functional Class of the roads connected to the Roundabout.

Level 1
  • Functional Class = 1 roads allow for high volume, maximum speed traffic movement between and through major metropolitan areas.
  • Functional Class = 1 is applied on roads with very few, if any, speed changes. Access to the road is usually controlled.
Level 2
  • Functional Class = 2 roads are used to channel traffic to Functional Class = 1 roads for travel between and through cities in the shortest amount of time.
  • Functional Class = 2 is applied on roads with very few, if any, speed changes that allow for high volume, high speed traffic movement.
Level 3
  • Functional Class = 3 is applied on roads that intersect Functional Class = 2 roads and provide a high volume of traffic movement at a lower level of mobility than Functional Class = 2 roads.
Level 4
  • Functional Class = 4 is applied on roads that provide for a high volume of traffic movement at moderate speeds between neighbourhoods. These roads connect with higher Functional Class roads to collect and distribute traffic between neighbourhoods.
Level 5
  • Functional Class = 5 is applied on roads with lower volume and traffic movement below the level of any other Functional Class.
  • The following also receive Functional Class = 5:
    • Walkways, truck only roads, bus only roads, and emergency vehicle only roads.

    • Access roads, parking lanes, and connections internal to certain POIs.

    • Roads in marginal and illegal settlements.

    • A U-turn lane receives Functional Class = 5 unless it is considered part of an intersection. A U-turn lane is considered part of an intersection if the presence of turn restrictions at the intersection forces the use of the U-turn road, as shown in the following figure.

      Figure 1. U-turn Lane in Intersection