Sometimes we get green lights, and sometimes we hit all the red lights on our commute to work. But, while sitting at a red light, have you ever wondered why traffic lights are red, yellow ...

Well, in the 1840s the British railroads adopted a flag, lamp and semaphore signal system where red meant danger, white meant safety and green indicated proceed with caution. They took their ...

Eventually, the upgrades could do away entirely with the red, yellow and green lights of today, ceding control to driverless cars. Henry Liu, a civil engineering professor who is leading a study ...