MonitoredVehicleJourney¶

Status¶

Normative

Definition¶

A MonitoredVehicleJourney represents the current operational state of a DatedVehicleJourney that is being monitored during execution.

It provides a canonical semantic representation of an ongoing public transport journey, including its observed operational status, current progress, and predicted future operation.

A MonitoredVehicleJourney is independent of any particular real-time data format or monitoring technology.

Identity¶

The semantic identity of a MonitoredVehicleJourney is established by the identity of the monitored operational journey.

It represents the real-time execution of one DatedVehicleJourney.

Its identity remains stable throughout the execution of that journey, regardless of updates received from monitoring systems.

For a regularly scheduled service, identity normally depends on:

DatedVehicleJourney
Operating Day

Where more than one monitored execution may correspond to the same DatedVehicleJourney on the same Operating Day, identity shall additionally include a start time, execution identifier, or another profile-defined discriminator.

The assigned PhysicalVehicle is not part of the semantic identity.

Real-time observations update the state of the MonitoredVehicleJourney but do not change its identity.

Motivation¶

Transport operators continuously publish operational information describing the current state of vehicle journeys.

Different technologies represent this information differently.

SCRA defines a canonical semantic model that captures the operational meaning independently of any implementation technology.

This enables consistent semantic interoperability across multiple monitoring systems.

Characteristics¶

A MonitoredVehicleJourney:

represents one journey currently being monitored;
exists only while operational monitoring is available;
evolves continuously as new observations become available;
remains independent of the PhysicalVehicle performing the journey;
remains independent of implementation technologies.

Relationships¶

A MonitoredVehicleJourney:

monitors one DatedVehicleJourney;
may currently be operated by one PhysicalVehicle;
may be referenced by zero or more PassingEvent entities representing scheduled, predicted, or observed operational events;
may be associated with operational observations;
may reference one or more monitoring sources.

Typical Properties¶

Typical properties include:

current operational status;
current geographical position;
current delay;
current bearing;
current speed;
occupancy information;
observation timestamp;
prediction timestamp;
current stop;
next stop.

Predicted, scheduled, and observed stop events are represented by associated PassingEvent entities rather than embedded predicted passing-time structures.

These properties are informative examples rather than mandatory attributes.

Conformance Requirements¶

A conforming MonitoredVehicleJourney shall include:

a stable semantic identity for the monitored execution;
one relationship to the applicable DatedVehicleJourney;
the applicable Operating Day or another profile-defined service-date discriminator.

The following conditional requirements apply:

a PhysicalVehicle relationship shall be present only when a vehicle is currently assigned and known;
a current geographical position shall include its applicable observation time;
a current delay shall conform to the normative delay calculation rules and shall have an applicable baseline time;
predicted, scheduled, or observed stop events shall be represented by associated PassingEvent entities;
prediction confidence shall be used only for predicted operational values;
occupancy information shall identify its applicable observation time or source context when required by the applicable profile.

The following information is optional unless required by an applicable profile:

the currently assigned PhysicalVehicle;
current geographical position;
current bearing;
current speed;
current delay;
occupancy information;
current stop;
next stop;
observation timestamp;
prediction timestamp;
references to monitoring sources.

A MonitoredVehicleJourney may be referenced by zero or more PassingEvent entities. Each associated PassingEvent shall reference exactly one MonitoredVehicleJourney.

Updates to an associated PassingEvent shall not alter the identity of the MonitoredVehicleJourney.

Origin¶

Typical sources include:

GTFS-Realtime VehiclePosition
GTFS-Realtime TripUpdate
SIRI Vehicle Monitoring
SIRI Estimated Timetable
Automatic Vehicle Location (AVL)
Operational control systems

The semantic model is independent of any particular source.

Mapping Guidance¶

Typical mappings include:

GTFS-Realtime → MonitoredVehicleJourney
SIRI → MonitoredVehicleJourney
AVL → MonitoredVehicleJourney
MonitoredVehicleJourney → NGSI-LD
MonitoredVehicleJourney → JSON-LD
MonitoredVehicleJourney → RDF
MonitoredVehicleJourney → MCP Resources

Mappings are informative and shall not modify the semantic definition.

Normative Realtime Relationships — Phase 3¶

The following relationships are normative for MonitoredVehicleJourney.

Relationship	Range	Normative semantics
`currentPoint`	`PointInJourneyPattern`	Current or next logical point in the journey pattern used to express monitored progress. It SHALL NOT be used as a stop-identity shortcut.
`currentStop`	`PublicTransportStop`	Current or next operational stop associated with monitored progress. It is distinct from `currentPoint`.
`operatedByVehicle`	`PhysicalVehicle`	Physical vehicle currently operating the monitored journey. It is distinct from the planned or assigned `DatedVehicleJourney.assignedVehicle` relationship.

currentPoint expresses logical progress in the journey pattern.

currentStop expresses the operational stop associated with that progress. A PointInJourneyPattern and a PublicTransportStop SHALL NOT be treated as interchangeable identifiers.

operatedByVehicle records the vehicle observed as operating the monitored journey. It SHALL NOT be interpreted as equivalent to assignedVehicle, because assignment and observed operation are separate facts.