In 1968, the first traffic lights were installed outside the Palace of Westminster in London.
The traffic lights towered six metres (20 feet) above the carriageway. Resembling railway signals, they used semaphore arms and were illuminated at night by red and green gas lamps.
Many drivers did not understand what the angled semaphore blades were supposed to indicate and the technology often broke down. In January 1869, a gas leak caused an explosion at the base of the semaphore, badly burning the face of the police operator.
The lights were used for a few months, but constant breakdowns and general ineffectiveness led to their removal by the end of the year. Traffic lights did not return to the capital until 1926, when a manually operated series of electric lights was installed along Piccadilly.