yellow light timing

Day in and day out for at least 30 years (and perhaps for almost a century), over 3,000 stoplights all across Chicago have whirred through tens of millions of cycles the exact same way: green, then yellow for three seconds, then red. Yet today, this three second cycle was suddenly declared a public safety emergency, with the Tribune's front page fomenting panic about the crisis posed by "risky" and "too short" yellow phases.