The First (Disastrous) Trial in England
December 10, 1868: the official birth date of the world’s first traffic light. It was installed at Parliament Square in London. The system was composed of two mobile signs attached to pivoting arms that were manipulated by a lever. The post was topped with a gas-lit semaphore to ensure visibility. But it was short-lived. Less than two months later, the traffic light exploded, killing the police officer who worked the signs.
https://www.inclusivecitymaker.com/1868-2019-a-brief-history-of-traffic-lights/