Segment subclass

[brad-richardson]

Description

The current segmentation process exclusively uses OSM's highway= tag during merging of segments. This results in segments that no longer distinguish the subparts. Here are some examples that contain two incompatible classes (sidewalk, crosswalk) which currently fallback to footway, causing the differentiating classes to be lost:

Service roads and footways are the most impacted and we can't fully capture the road network with our schema as it stands. The proposal is to add a new scope-able subclasses property.

Reference

1. https://github.com/OvertureMaps/tf-transportation/issues/248
2. https://wiki.overturemaps.org/display/PROJ/Footway+and+Service+Road+Segmentation+Error+Handling

Testing

Verified tests passed

Checklist

Checklist of tasks commonly-associated with schema pull requests. Please review the relevant checklists and ensure you do all the tasks that are required for the change you made.

1. Add relevant examples.
2. Add relevant counterexamples.
3. Update any counterexamples that became obsolete. For example, if a counterexample uses property A but is not intended to test property A's validity, and you made a schema change that invalidates property A in that counterexample, fix the counterexample to align it with your schema change.
4. Update in-schema documentation using plain English written in complete sentences, if an update is required.
5. Update Docusaurus documentation, if an update is required.
6. Review change with Overture technical writer to ensure any advanced documentation needs will be taken care of, unless the change is trivial and would not affect the documentation.

Documentation Website

Docs preview for this PR.

[jenningsanderson]

Adding 1 more stamp (implicit Meta approval from Brad)