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Ubiquitous language

Terms used consistently across code, docs, conversations, and PR descriptions. If a name conflicts here, this page wins.

Transit primitives​

  • GTFS — General Transit Feed Specification. Open standard for static transit data (routes, stops, schedules).
  • GTFS-RT — GTFS Realtime. Protocol Buffers-based extension. Not provided by RJ-SMTR; we use SPPO REST instead.
  • SPPO — Sistema de Transporte Público por Ônibus. Rio's bus operator data system. Provides REST JSON GPS feed for buses and BRT.
  • BRT — Bus Rapid Transit. In Rio: TransOeste, TransCarioca, TransOlimpica, TransBrasil.
  • VLT — Veículo Leve sobre Trilhos. Modern light rail in downtown Rio.
  • MetroRio — Rio's subway. Privately operated. No public real-time API. Phase 2 synthetic GTFS only.
  • SuperVia — Rio's commuter rail. Privately operated. No public real-time API. Phase 2 synthetic GTFS only.
  • OTP — OpenTripPlanner v2. Open-source multi-modal trip planner.

Data shapes​

  • Hypertable — TimescaleDB's time-partitioned table abstraction. vehicle_positions is one, partitioned by recorded_at with 1-day chunks.
  • Continuous aggregate — TimescaleDB's incrementally maintained materialized view.
  • Bundle — the offline data package downloaded by clients (GTFS plus precomputed aggregates).
  • Headway — time between consecutive vehicles on the same line.
  • Dwell time — time a vehicle spends stopped at a stop.
  • Geofence — virtual perimeter around a location used to trigger alerts.

Identity and timing​

  • Device ID — anonymous UUID generated on first app launch. Scopes favorites and alert rules before optional Phase 2 login.
  • recorded_at — GPS fix time on the vehicle (SPPO datahora). Source-of-truth for trajectory math.
  • sent_at — vehicle→server transmission time (SPPO datahoraenvio).
  • received_at — server arrival time (SPPO datahoraservidor). Source-of-truth for "is this vehicle live now."

Other​

  • FCM — Firebase Cloud Messaging. Push delivery channel.