"Special Traffic Figure" vs "Roundabout"

Symptom: A junction looks like a roundabout but should be mapped as a Special Traffic Figure

Customer symptoms:

A traffic feature appears visually similar to a roundabout, but routing behavior does not match standard roundabout expectations.
Voice guidance uses instructions such as “take the first exit”, “take the second exit”, or similar roundabout-style maneuvers.
Map editors are uncertain whether to classify the feature as a standard roundabout or a Special Traffic Figure.
A loop-shaped intersection contains road segments with different directions of travel.
A road crosses at grade within the loop structure, creating behavior that differs from a standard roundabout.

Answer:
A Special Traffic Figure (STF) may look and feel like a standard roundabout for drivers, and navigation systems may still provide roundabout-style guidance such as “take the first, second, or third exit.” However, it must be mapped as a Special Traffic Figure when the intersection contains characteristics that prevent it from being represented as a normal roundabout.

Classification:
Behavior Type: Expected behavior / Data modeling requirement.

Root Cause
A standard roundabout assumes a consistent circular traffic flow and intersection structure. A Special Traffic Figure is required when the geometry or traffic flow contains conditions that are not compatible with a normal roundabout model. Examples include:

1. A section of the loop contains a different direction of travel than the remainder of the circular structure.
2. A road crosses at grade within the loop area of the intersection.





Impact:
If a qualifying intersection is modeled as a standard roundabout instead of a Special Traffic Figure:

Junction representation may not accurately reflect the intersection design.
Maneuver generation and routing interpretation can become inconsistent with the physical road layout.
Quality and consistency of map data may be affected.

Expected Behavior:
Map the feature as a Special Traffic Figure when:

Part of the loop has a different direction of travel.
A road crosses at grade within the loop.

Navigation guidance may still be expressed in a roundabout-style format (for example, “take the second exit”), even though the junction is represented as a Special Traffic Figure.

Unexpected Behavior:
The junction should not be modeled as a standard roundabout when either of the Special Traffic Figure conditions described above exists. Doing so does not accurately represent the intersection structure.





Recommended Actions:

1. Review the traffic flow around the loop.
2. Verify whether any segment of the loop uses a different direction of travel.
3. Check whether a road crosses at grade within the loop.
4. If either condition is present, classify and map the feature as a Special Traffic Figure rather than a normal roundabout.
5. Validate associated connectivity and maneuver behavior after mapping changes.

Product Scope:

Product: HERE Mapping Content / CSM Editing Workflows
Feature Area: Junction Modeling and Traffic Figure Classification
* Applicability: Intersections that visually resemble roundabouts but contain non-standard loop or crossing characteristics.

Keywords / Tags:
Special Traffic Figure, STF, Roundabout, Complex Intersection, Junction Modeling, Traffic Flow, Loop Intersection, At-Grade Crossing, Navigation Guidance, Exit Maneuver, Map Editing, Road Network, Intersection Classification, Routing, HERE Maps.