AVL with Road-Graph Routing and Live ETA

Overview#

Every ambulance in your fleet is tracked in real time, with road-routed ETAs that update continuously as traffic shifts and units move.

Knogin Argus continuously tracks Automatic Vehicle Location (AVL) for every vehicle in the fleet, computes travel time over a live road graph rather than straight-line distance, and recomputes ETA as traffic conditions and position updates arrive. Full-frequency telemetry is retained in a high-volume, time-partitioned positions store, while a sampled trail of position events feeds the canonical incident timeline so a watch-commander can review a unit's exact path of travel alongside every other event in the case.

Key Features#

• Continuous Fleet AVL: Every vehicle reports position continuously through a provider-agnostic ingest layer, so the command board reflects the live state of the fleet rather than a periodic snapshot.

• Road-Graph Routed ETA: Travel times are computed across a live road network using an open routing engine, so ETAs reflect real road geometry and prevailing conditions rather than straight-line distance.

• Live ETA Recomputation on Traffic Deltas: A background route-refresh process keeps travel-time data warm, so ETAs update automatically as traffic conditions and unit positions shift.

• Automatic Primary Unit Rotation: When a closer unit overtakes the currently assigned primary mid-journey, the dispatch engine rotates the primary assignment and records that rotation as a first-class event on the incident timeline.

• Partitioned Positions Store: Full-frequency GPS samples flow into a high-volume store partitioned by month and linked to vehicles and incidents, keeping detailed telemetry queryable without impacting live operational tables.

• Canonical Timeline Sampling: A reduced cadence of position events (for example, every thirty seconds or on incident-relevant zone crossings) is promoted to the canonical incident timeline so the unit's path of travel becomes part of the unified incident record.

• First-Class Vehicle Domain: Vehicles are modelled as first-class entities with telemetry associations, so location, assignment, and incident history can be reasoned about per asset across the operational picture.

• Multi-Source Telemetry Ingest: GPS sentence streams, cellular telematics, Trimble TAIP feeds, and CAN-bus signals are normalised through dedicated protocol adapters before reaching the unified service, so heterogeneous in-vehicle hardware is supported in a single fleet.

• Outbound Geospatial Publishing: Vehicle observations can be republished through an OGC SensorThings-aligned channel, so partner mapping and operational-picture systems consume positions through open geospatial patterns.

• Command Board and In-Vehicle Surfaces: Live position and ETA render on the dispatcher command board map and inside the responder mobile in-vehicle navigation view, so dispatchers and crews share the same operational picture.

Use Cases#

Emergency Ambulance Dispatch#

A control-room dispatcher watches every ambulance's road-routed ETA update in real time as units move, traffic shifts, and new incidents are accepted. The shared operational picture eliminates phone-based status checks.

Closer-Unit Rotation Mid-Journey#

While a primary ambulance is en route to an incident, a second unit clears nearby. The platform automatically reassigns the primary and records the rotation on the canonical incident timeline for post-incident review and regulatory audit.

In-Vehicle Navigation Continuity#

A crew uses the in-vehicle navigation view on the responder mobile application, always showing the same routed ETA the command board is displaying for that unit.

Watch-Commander Path Review#

After-action review of an incident shows the responding unit's sampled path of travel in the canonical timeline alongside dispatch decisions, status changes, and on-scene events, supporting both operational learning and formal investigation.

High-Volume Position Analytics#

Operational analysts query the time-partitioned positions store by month to study response patterns, dwell times, and fleet utilisation without touching live dispatch tables.

Mixed Telemetry Fleet#

A fleet combining GPS sentence receivers, cellular telematics units, Trimble TAIP transponders, and CAN-bus equipped heavy vehicles is normalised into a single operational AVL view through protocol-specific adapters.

Integration#

Argus exposes the AVL and routing capability through standard API surfaces that work with your existing CAD, GIS, and fleet management tools.

• Provider-agnostic AVL ingest: REST endpoints accept position data in any of the supported wire formats (NMEA, ETSI TS 102 708, TAIP, SAE J2540/J1939). Each endpoint is tenant-scoped and secured with OAuth 2.0 bearer tokens.

• GraphQL operational query layer: Live unit positions, current ETA, and assignment state are queryable and subscribable via the platform's GraphQL API, so command board and mobile surfaces can maintain a real-time view with a single connection.

• Road-graph routing: Route and ETA computation is performed against an OpenRouteService instance backed by global OpenStreetMap data. Route geometry is returned as GeoJSON so it can be rendered on any standards-compliant mapping client.

• OGC SensorThings outbound feed: Each vehicle is registered as an OGC SensorThings Thing; individual position observations are published as Observations, allowing partner operational-picture and GIS systems to consume the fleet feed through an open geospatial API.

• Canonical incident timeline events: Position samples and rotation events are published using a CloudEvents 1.0 envelope, making them consumable by any downstream subscriber including audit systems, analytics pipelines, and third-party CAD integrations.

• Webhook and push notifications: Dispatchers and integration partners can subscribe to rotation and ETA-threshold events delivered as HTTP webhooks with CloudEvents payloads.

• Normalised position model: All observations, regardless of source protocol, are normalised to WGS 84 (EPSG:4326) decimal-degree coordinates before storage and publication, ensuring consistent behaviour across all downstream consumers.

Open Standards#

• NMEA 0183: GPS sentences from in-vehicle receivers are ingested and validated using the standard maritime and vehicular positioning sentence format.

• ETSI TS 102 708: Cellular fleet telematics (TETRA AVL) are consumed using the European telematics specification for vehicle location reporting over cellular networks.

• TAIP (Trimble ASCII Interface Protocol): Position frames from Trimble and compatible transponders are decoded using the publicly documented TAIP message format.

• SAE J2540 / SAE J1939-71: CAN-bus position and navigation frames from heavy vehicles are ingested using the SAE J2540 Messages for Navigation standard and the SAE J1939-71 Vehicle Application Layer PGN definitions.

• GeoJSON (RFC 7946): Route geometry and position payloads are encoded using the standard JSON format for geographic data structures.

• WGS 84 / EPSG:4326: All positions and routes are referenced to the standard global geodetic datum expected by modern mapping and GIS systems.

• OGC SensorThings API: Outbound vehicle observations are published in conformance with the Open Geospatial Consortium SensorThings API for sensor and IoT data fusion.

• OpenStreetMap: The road network underlying route and ETA computation is sourced from the openly licensed OpenStreetMap dataset via OpenRouteService, ensuring global coverage and community-maintained accuracy.

• CloudEvents 1.0: Position sample events and unit-rotation notifications are wrapped in the CloudEvents 1.0 envelope so any conformant event broker or subscriber can consume them without proprietary bindings.

• AsyncAPI 2.6: The AVL event channel is documented using the AsyncAPI specification, enabling downstream teams to generate typed clients against a published contract.

• W3C Geolocation API: Responder mobile devices can fall back to the standard browser and mobile geolocation surface for position reporting where dedicated in-vehicle hardware is unavailable.

• OAuth 2.0 / JWT: All ingest and query endpoints are secured using OAuth 2.0 bearer tokens encoded as JSON Web Tokens, consistent with the platform-wide identity model.

Security and Compliance#

• All telemetry ingest endpoints are tenant-scoped; position data from one organisation is never visible to another, satisfying per-tenant data sovereignty requirements.
• Full-frequency position records are retained with immutable timestamps, supporting audit-trail and data-lineage requirements for operational review, formal investigation, and regulatory inspection.
• Unit-rotation events are written to the canonical incident timeline as first-class, tamper-evident records, providing a verifiable chain of custody for dispatch decisions.
• Access to live fleet positions and historical telemetry is governed by role-based permissions, ensuring that sensitive operational-picture data is available only to authorised personnel.

Last Reviewed: 2026-05-05 / Last Updated: 2026-05-05