Lane Geometry Model

Lane Group Reference Line

Each Lane Group has a 3D polyline representing the overall geometric shape of the Lane Group. It spans from the Start Lane Group Connector to the End Lane Group Connector.

The ends of all Lane Group Reference Lines at a given Lane Group Connector are required to have consistent 3D bearing (tangent) and 3D curvature. There is no requirement for geometric continuity between Lane Group Reference Lines at adjacent Lane Groups. These lines do not have to meet, but they all must have the same bearing and curvature.

Figure 1. Lane Group Reference Line Example with Lanes Forming/Ending

Figure 2. Lane Group Reference Line Example at a 3-way Intersection

Figure 3. Lane Group Reference Line Example at a 4-way Intersection

Figure 4. Lane Group Reference Line Example at a Branching Off-ramp

Figure 5. Lane Group Reference Line Example at an Off-ramp Separating from the Main Road

Lane Boundaries

Each Lane has two 3D boundaries, one on each of its sides. For the outermost lanes, the outer boundary will coincide (at a 2D level) with the Lane Group Boundary. The outer boundaries are the left boundary of lane 1 and the right boundary of the highest-numbered lane. Other boundaries can be shared between lanes when they are adjacent: the right boundary of lane 1 is the left boundary of lane 2, and so on.

Lane Boundaries are expected to be geographically continuous across Lane Group Connectors in all 3 dimensions (latitude, longitude, and elevation).

Figure 6. Lane Boundaries Geometry Example with Lanes Forming/Ending

Figure 7. Lane Boundary Example at a 3-way Intersection

Figure 8. Lane Boundary Example at a 4-way Intersection

Figure 9. Lane Boundary Example at a Branching Off-ramp

Figure 10. Lane Boundary Example at an Off-ramp Separating from the Main Road

Lane Path Geometry (Lane Drive Path)

Each Lane has a single 3D Lane Path geometry, or Lane Drive Path, representing a nominal path through the lane.

Lane Path Geometries are expected to be 3D continuous where they meet at Lane Group Connectors.

Figure 11. Lane Path Geometry Example with Lanes Forming/Ending

Figure 12. Lane Path Geometry Example at a 3-way Intersection

Figure 13. Lane Path Geometry Example at a 4-way Intersection

Figure 14. Lane Boundary Example at a Branching Off-ramp

Figure 15. Lane Boundary Example at an Off-ramp Separating from the Main Road

Additional Lane Geometry Constraints

All geometries at a Lane Group Connector have the same elevation where they (2D) touch the Lane Group Connector. This applies to the Lane Group Reference Lines, Lane Boundaries, and Lane Paths.