{
  "schema_version": "1.0",
  "integration_version": "vta-data-coverage-web-1.0",
  "generated_at": "2026-08-06T21:04:34.840629+10:00",
  "official_tirtl_source": {
    "title": "TIRTL Traffic Counts and Classification",
    "publisher": "Department of Transport and Planning, Victoria",
    "url": "https://opendata.transport.vic.gov.au/dataset/tirtl-traffic-counts",
    "license": "Creative Commons Attribution 4.0",
    "update_frequency": "Daily",
    "resolution": "15-minute aggregate bins by date, time, site, heading, Austroads vehicle class and speed bin",
    "start_date": "2025-11-01",
    "end_date": "2026-08-04",
    "last_updated_date": "2026-08-05",
    "inclusive_days": 277,
    "weeks": 39,
    "extra_days": 4,
    "weeks_text": "39 weeks and 4 days",
    "calendar_months_represented": 10
  },
  "governed_tirtl_coverage": {
    "start_date": "2025-11-01",
    "end_date": "2026-05-21",
    "inclusive_days": 202,
    "weeks": 28,
    "extra_days": 6,
    "weeks_text": "28 weeks and 6 days",
    "calendar_months_represented": 7,
    "overnight_window": "10:00 pm to 6:00 am",
    "classified_records_display": "3.13B+",
    "truck_passings_display": "159.6M+",
    "west_gate_tunnel_opening_date": "2025-12-14",
    "pre_opening_nights": 43,
    "on_or_after_opening_nights": 159,
    "classification": "Mixed pre-opening, opening-transition and early-operation reference"
  },
  "scats_coverage": {
    "start_year": 2014,
    "start_date": null,
    "start_precision": "year",
    "end_date": "2026-04-07",
    "history_display": "12+ years",
    "suburbs_display": "517 Victorian suburbs",
    "resolution": "15-minute signal-derived traffic movement observations",
    "semantics": "SCATS movements are signal-derived movement observations, not simple unique-vehicle counts.",
    "inclusive_days": null,
    "weeks_text": null,
    "calendar_years_represented": 13
  },
  "governed_release_metrics": {
    "stage22": {
      "version": "22.0.1",
      "status": "PASS",
      "source_manifest": "A:\\TrafficAnalytics\\VTA\\Political_Accountability\\stage22\\vta_stage22_20260806_122922\\vta_stage22_build_manifest.json",
      "site_heading_count": 562,
      "robust_site_heading_count": 283,
      "public_pair_count": 119,
      "excluded_night_count": 20,
      "eligible_paired_night_count": 20401
    },
    "stage23a4": {
      "version": "23A.4.0",
      "status": "PASS",
      "source_manifest": "A:\\TrafficAnalytics\\VTA\\Political_Accountability\\stage23a4\\vta_stage23a4_20260806_151133\\vta_stage23a4_build_manifest.json",
      "reference_freeze_id": "VTA_STAGE23A4_P85_20251101_20260521",
      "tier_a_heading_count": 269,
      "tier_b_heading_count": 12,
      "tier_c_heading_count": 2,
      "complete_speed_hour_count": 374900,
      "eligible_speed_night_count": 46697
    }
  },
  "analytical_windows": [
    {
      "section": "Overnight freight rankings",
      "anchor": "overnight-rankings",
      "release": "Stage 17",
      "purpose": "Direction-level recorded overnight TIRTL rankings and evidence classes.",
      "period_start": "2025-11-01",
      "period_end": "2026-05-21"
    },
    {
      "section": "Political accountability",
      "anchor": "political-accountability",
      "release": "Stage 20.2",
      "purpose": "Corrected community and strategic-network exposure joined to political geography.",
      "period_start": "2025-11-01",
      "period_end": "2026-05-21"
    },
    {
      "section": "Temporal pressure",
      "anchor": "temporal-pressure",
      "release": "Stage 21",
      "purpose": "Complete eight-hour overnight onset, persistence and release profiles.",
      "period_start": "2025-11-01",
      "period_end": "2026-05-21"
    },
    {
      "section": "Two-way corridor evidence",
      "anchor": "two-way-corridors",
      "release": "Stage 22.0.1",
      "purpose": "Governed paired-site two-way volume, balance, dominance and persistence.",
      "period_start": "2025-11-01",
      "period_end": "2026-05-21"
    },
    {
      "section": "Speed pressure and reliability",
      "anchor": "speed-pressure",
      "release": "Stage 23A.4.0",
      "purpose": "Tier A governed point-speed pressure, hourly reference and reliability evidence.",
      "period_start": "2025-11-01",
      "period_end": "2026-05-21"
    },
    {
      "section": "Freight operator commercial intelligence",
      "anchor": "commercial-gold",
      "release": "Commercial Gold",
      "purpose": "Operator-facing screens derived from governed Stage 22 and Stage 23A.4 evidence.",
      "period_start": "2025-11-01",
      "period_end": "2026-05-21"
    }
  ],
  "coverage_boundary": "The overall date range does not mean every detector or heading operated continuously. Devices can experience outages, commissioning or decommissioning, and individual locations can have different temporal ranges. Missing intervals are not interpreted as zero traffic. Sensor passings are not unique vehicles or complete journeys.",
  "timeline": {
    "official_start_pct": 0,
    "opening_pct": 15.58,
    "governed_end_pct": 72.83,
    "official_end_pct": 100
  }
}