This was quite a week for transportation–we had the first licensed taxicabs, and on December 10, 1868 the first traffic light was installed outside the Palace of Westminster in London.
Railroad engineer J.P. Knight was the man behind the light, which is why the first light actually resembled a railroad crossing signal instead of the lights familiar to us today. The first traffic light featured semaphore arms that lowered, with red and green gas lamps so they’d be visible at night. A policeman had to stand next to the light and turn it manually so the correct color faced the right way.
The first light lasted less than a month: On January 2, 1869 it exploded, either injuring or killing the policeman operating it. Despite this setback, others continued to perfect the light until we wound up with the version we see today.