Assertion: traffic light | /r/HasProperty | gas-powered
Facets:
value: in the event of a leak
type: TEMPORAL
Source sentences:
text: They were red and green, gas-powered, and more than a little dangerous in the event of a leak.
text: The attempt to control traffic was first demonstrated during the Roman Empire, but it was 1868 before the first breakthrough was made, when J.P Knight, a railway signal engineer designed the first traffic light, near Westminister Abbey in London which was powered by gas.