Data sources — dev diagnostics

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State / feedStatic (timetable)Vehicleswith ts Position age — medianp90maxStatusTimetable rebuild

How it syncs. Static (timetable: routes, stops, shapes) is built from each state's GTFS zip and refreshes only when rebuilt — use the Rebuild button per row. Live vehicle positions come from each state's GTFS-Realtime feed; our server polls every ?, the web client polls every ?, and tweens between snapshots over ~?.

Lag (feed vs reality). "Position age" is how old each vehicle's GPS fix is inside the feed (provider-side lag we can't remove) — note how the median can be small while p90/max run into minutes. Total on-screen lag ≈ position age + up to one server poll + up to one client poll + tween. The provider lag dominates; the median is what the state line in the app shows.