Why is a road assigned Functional Class 1, 2, 3, 4, or 5?

Symptoms
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A road appears to have a different priority than nearby roads in routing results.
Long-distance routes prefer some roads over others even when alternative roads exist.
A customer expects a road to be treated as a major route, but it is classified at a lower level.
Questions arise about why certain roads are used to connect neighborhoods to highways.
Confusion about how the routing engine prioritizes roads across different regions or countries.

Answer
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Functional Class (FC) is a hierarchical road classification used by HERE map data and routing services to optimize route calculation. Roads with higher functional importance receive a higher Functional Class ranking and are generally preferred for long-distance travel, while lower Functional Class roads primarily support local access. The Functional Class network is designed to remain connected so that routing algorithms can efficiently navigate between locations using roads of equal or higher importance where appropriate.

Root Cause
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Roads are classified according to their role within the overall transportation network rather than solely by road name, ownership, or local significance. Functional Class assignment reflects factors such as traffic movement, connectivity, access control, mobility, and the road's role in linking cities, regions, neighborhoods, and local destinations.

Impact
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Functional Class directly influences route calculation, map display behavior, and network hierarchy. Differences in road density and infrastructure between countries and regions can result in variations in Functional Class distribution while still maintaining consistent routing principles.

Functional Class Levels
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### Functional Class 1

The highest Functional Class level. These roads support maximum-speed, high-volume traffic movement between major metropolitan areas. Access is typically controlled, and speed changes are minimal. Examples commonly include major motorways and primary national highway corridors.

### Functional Class 2

High-volume, high-speed roads that connect metropolitan areas and major cities. These roads channel traffic toward Functional Class 1 roads and support efficient intercity travel with limited speed variation.

### Functional Class 3

Roads that provide significant traffic movement at a lower mobility level than Functional Class 2. They commonly intersect or connect with Functional Class 2 roads and serve important regional travel functions.

### Functional Class 4

Roads that support moderate-speed, higher-volume traffic movement between cities, districts, or neighborhoods. They connect local road networks to higher Functional Class roads and help distribute and collect traffic.

### Functional Class 5

All remaining roads and walkways that are not classified as Functional Class 1 through 4. These roads primarily provide local access within neighborhoods, subdivisions, or similar local areas.

Expected Behavior
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Functional Classes 1 through 4 form the primary connected navigation network and must be open to automobile traffic.
Route calculation generally favors higher Functional Class roads for longer journeys.
Functional Class assignments may differ across regions due to differences in real-world road infrastructure.
* The network should remain connected, allowing travel between roads of the same Functional Class through links of the same or higher Functional Class, except in limited cases such as dead-end roads.

Keywords
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Functional Class, FC1, FC2, FC3, FC4, FC5, road hierarchy, routing, route calculation, navigation network, highway classification, road priority, map data, road connectivity, transportation network, HERE Maps, routing behavior, road categorization