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Definition
Functional Requirements
Syntax
Semantics
Conformance Testing
Performance Assessment

1      Definition

Road State is a Data Type describing the current physical, environmental, geometric, and traffic‑related conditions of a specific road segment. It provides the information required by MPAI‑CAV components to assess the state of the infrastructure relevant to perception, prediction, and decision‑making.

2      Functional Requirements

Road State shall satisfy the following requirements:

  • Identification – Road State shall identify the CAV producing the information and the road segment to which the state applies.
  • Temporal validity – Road State shall specify the time of creation and the validity interval of the described state.
  • Road attributes – Road State shall provide static or slowly varying attributes of the road segment.
  • Surface condition – Road State shall describe the current condition of the road surface, including wetness, snow, ice, contaminants, and confidence.
  • Weather conditions – Road State shall reference weather information relevant to driving, including temperature, humidity, precipitation, wind, fog, and ice.
  • Hazards – Road State shall describe hazards present on or near the road segment, including type, location, severity, spatial extent, recommended action, and confidence.
  • Dynamic road geometry – Road State shall represent temporary changes to road geometry, such as lane closures, temporary lane boundaries, temporary curvature, speed limits, and signage.
  • Traffic conditions – Road State shall describe traffic flow and traffic jams affecting the road segment.
  • Cooperative perception – Road State shall represent information obtained from cooperative perception sources, including shared objects, occupancy grids, free‑space maps, and predicted trajectories.
  • Fusion metadata – Road State shall describe the fusion of multiple sources, including source list, fusion method, conflict resolution strategy, and overall confidence.
  • Predictions – Road State shall provide predictions of the evolution of traffic, weather, and hazards over time.
  • Metadata and traceability – Road State shall include MPAI‑PTF Data Exchange Metadata to support data exchange, logging, and interpretation.

3      Syntax

https://schemas.mpai.community/CAV2/V1.1/data/RoadState.json

4      Semantics

Table 1 – Semantics of the Road State Data Type

Label
Description
Header Road State Header – Standard “CAV‑RDS‑Vx.y”.
MInstanceID Identifier of the M-Instance (Virtual Space) associated with this Road State.
UEnvironmentID Identifier of the U-Environment (Real Space) associated with this Road State.
RoadStateID Unique identifier of this Road State instance.
RoadStateTime Time this Road State was produced.
RoadStateSpaceTime Space/Time where/when this Road State applies.
CAVID Identifier of the CAV producing this Road State.
Segment Identifier of the road segment to which this Road State applies.
RoadAttributes Static or slowly varying attributes of the road segment (lanes, surface type, curvature, slope).
SurfaceCondition Current condition of the road surface (wetness, snow, ice, friction, contaminants, confidence).
WeatherData Weather information relevant to driving.
Hazard[] Hazards present on or near the road segment (type, location, severity, extent, recommended action, confidence).
DynamicRoadGeometry Temporary modifications to the road geometry (lane closures, boundaries, curvature, speed limits, signage).
TrafficFlow Traffic flow information per lane (flow, mean speed, vehicle class distribution, stop-and-go index, confidence).
TrafficJam Traffic jam information (location, length, severity, estimated delay, confidence).
CooperativePerception Information from cooperative perception sources (shared objects, occupancy grid, free-space map, predicted trajectories).
FusionMetadata Information describing the fusion of multiple sources (source list, method, conflict resolution, confidence).
Predictions Predicted evolution of traffic flow, weather, and hazards.
DataXMData MPAI-PTF Data Exchange Metadata providing provenance, authorisation, legal, security, and confidence information associated with this Road State in a trusted data exchange context.
DescrMetadata Human-readable descriptive metadata of the Road State (plain text, max 2048 characters).

5      Conformance Testing

A Data instance conforms with Road State (CAV‑RDS) if:

  1. The Data validates against the Road State’s JSON Schema.
  2. All Data in the Road State’s JSON Schema:
    1. Have the specified type.
    2. Validate against their JSON Schemas.
    3. Conform with their Data Qualifiers.

6      Performance Assessment

Not part of this specification.

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