{
  "patent_number": "US 1475024",
  "country": "US",
  "title": "How Garrett Morgan Invented the Three-Position Traffic Signal",
  "original_title": "Traffic signal",
  "summary": "Garrett Morgan's 1923 patent for a T-shaped traffic signal introduced a 'caution' position to manage vehicle flow more safely at busy intersections.",
  "what_it_does": "The patent describes a T-shaped pole featuring three distinct positions to control traffic flow. Unlike earlier two-position signals that only signaled 'stop' or 'go', this design introduced a third state to halt traffic from all directions simultaneously. This allowed for a safer transition period, preventing collisions between vehicles clearing the intersection and those just starting to move.",
  "what_it_does_not_cover": [
    "Does not cover electric or automated traffic light systems.",
    "Does not cover signals that use colored lights (red, yellow, green) as the primary indicator.",
    "Does not cover systems that detect vehicle presence via sensors or loops."
  ],
  "filed": "1922-02-27",
  "granted": "1923-11-20",
  "expires": "1942-02-26",
  "status": "expired",
  "holder": "Individual",
  "holder_url": "https://patentbrief.org/company/individual",
  "inventors": [
    {
      "name": "Garrett A Morgan",
      "url": "https://patentbrief.org/inventor/garrett-a-morgan"
    }
  ],
  "times_cited": 2,
  "tags": [
    "automotive",
    "mechanical"
  ],
  "abstract": null,
  "url": "https://patentbrief.org/patent/us/1475024/traffic-signal-morgan",
  "markdown_url": "https://patentbrief.org/patent/us/1475024/traffic-signal-morgan/md",
  "google_patents_url": "https://patents.google.com/patent/US1475024",
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}