R73 - woven-planet/opensafety-mbse GitHub Wiki
Crosswalk Access is a Roadside Crosswalk Access, Island Crosswalk Access or Median Crosswalk Access
These appear to be the only safe places where a pedestrian may enter or exit a Crosswalk.
<subclass>.(ID, Road segment) -> Crosswalk Access.(ID, Road segment)
Crosswalk Access.Road segment is the union of all subclass Road segment values.