Who invented traffic lights?

谁发明了交通灯？

我们每天都会经过十字路口，也会顺其自然地看到红绿灯，“红灯停、绿灯行、黄灯要注意！”这是我们从小就会熟稔于心的。那么你知道这红绿灯到底是谁发明的，是从什么时候开始出现的呢？

The world's first traffic lights were installed near London's House of Commons (英国伦敦议会大厦) in 1868. They were invented by J P Knight. They had only red and green signals. Red meant "stop" and green meant "caution".?