4.3 Route Membership Problems
Route Membership problems are not yet implemented. This document defines the conceptual framework for future implementation.
Route Membership problems identify inconsistencies in the relationship between stops and routes. These apply only to routes that exist in both datasets.
Key Question: "Is the list of stops for this route consistent and correct?"
4.3.1 Membership Mismatch
Definition: A stop is included in a route in one dataset but is missing from that route in the other.
- Missing in OSM: ATLAS says Stop A serves Route X, but Stop A is not a member of the Route X relation in OSM.
- Missing in ATLAS: OSM says Stop A is a member of Route X, but ATLAS data does not show this service.
Example: "Zürich HB" is served by "S3" in ATLAS, but the OSM node for "Zürich HB" is not part of the "S3" relation.
4.3.2 Sequence Mismatch
Definition: The set of stops matches, but their ordering (sequence) in the route differs.
Detection Method:
- Compare the ordered list of stops for the matched route.
- Calculate the deviation (e.g., Levenshtein distance or percentage difference).
Priority Criteria:
- P1: >40% sequence difference (implies broken topology).
- P2: 10-40% difference.
- P3: <10% difference.
4.3.3 Direction Mismatch
Definition: A stop is a member of the route in both datasets, but the directional context differs.
- Direction:
forwardvsbackward, or specific destination names ("Towards A" vs "Towards B"). - Platform: The route serves Platform 1 in ATLAS but Platform 2 in OSM (if modeled as separate nodes).
Example: ATLAS shows Stop A serves Route X "Towards City", OSM shows it serves Route X "Towards Suburb".