Consume a GTFS-Realtime TripUpdates feed for predicted arrival/departure times
domain: gtfs.org · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Fetch the agency's designated TripUpdates protobuf endpoint (agencies typically expose separate URLs per feed type)
Decode the binary using the official gtfs-realtime.proto schema referenced at gtfs.org/documentation/realtime/reference/
Read FeedHeader.timestamp first to confirm feed recency before trusting any entity
Iterate FeedEntity.trip_update records, matching trip_id/route_id (and optionally start_date) back to the corresponding static GTFS trip
Use StopTimeUpdate arrival/departure delay or time fields to compute predicted times per stop
Known gotchas
Each trip should have at most one TripUpdate entity in the feed; duplicate or conflicting entities indicate a producer bug, not something to silently merge
TripUpdates only makes sense paired with the matching static GTFS Schedule feed version — matching against a stale static feed produces wrong stop sequences
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