交通信号灯为何用红色、黄色和绿色？_公共英语阅读理解

交通信号灯为何用红色、黄色和绿色？

Red means "stop," green means "go," and yellow means "hurry up and make that damn light." Why those colors, though? Why not blue, purple, and brown? I have to admit that aside from a hunch that it had to do with wavelengths, I had no idea myself, so I decided to look into it.

红灯“停”，绿灯“行”，黄灯亮了“快点走”，但为什么交通信号灯要用这三个颜色，而不用蓝色、紫色或者褐色呢？必须承认除了直觉认为这与波长有关外，我完全不知道原因，所以我决定一探究竟。

The answer, as it turns out, is a little convoluted, but makes sense. The earliest traffic signals were designed for trains, not cars. They were red and green, gas-powered, and more than a little dangerous in the event of a leak.

事实证明，答案确实有点复杂，不过倒也还讲得通。最早的交通信号灯是为火车而不是汽车通行设计。信号灯为红色和绿色，使用煤气，在漏油时会非常危险。

交通信号灯为何用红色、黄色和绿色？1

• Red is an inherited symbol from railroads

红色源于铁路信号灯

Red symbolizes danger in many cultures, which makes sense, considering it has the longest wavelength of any color on the visible spectrum, meaning you can see it from a greater distance than other colors. Red has meant stop since long before cars existed, with train signals' use of red dating back to the days when mechanical arms lifted and lowered to indicate whether the rail ahead was clear. So that one's simple.