Traffic signals rule our lives, so when the man who ruled D.C. traffic signals retired, many readers paid attention. Dear Dr. Gridlock: Fast, informative and written just for locals.

Called semaphore traffic lights, they had retractable arms — similar to railroad crossing arms — with the words “stop” and “go” on them. They would also have only red and green lights.

Some cities didn’t wait for new green-light technology before plugging in LEDs. Anaheim converted 3,753 red signals at 273 intersections two years ago, saving about $214,000 a year, officials said.

Updated: Nov 13, 2022 / 10:05 AM CST (WHTM) — We see traffic lights all the time. Sometimes we sail past green lights, and sometimes we hit every red light on our commute to work.

August 16, 2016 / 9:05 AM EDT / CBS Boston DETROIT (AP) — Audi is introducing an industry-first system that tells drivers how long it will take for a traffic light to change from red to green.

As Lebsock told us, “Current law allows red-light cameras on every single intersection with a traffic light. That’s tens of thousands of intersections. This bill sets reasonable parameters.” ...

Researchers are exploring ways to use features in modern cars, such as GPS, to make traffic safer and more efficient. Eventually, the upgrades could do away entirely with the red, yellow and green ...

Why the traffic light colors were chosen There are a few reasons why the colors red, yellow and green were chosen for traffic lights. Red is an obvious choice.

The yellow light didn’t enter the scene until the 1920s. William Potts, who was a police officer in Detroit, is credited with designing the first three- and four-way colored traffic lights.

Smarter vehicles could mean some of the most dramatic changes for the traditional traffic signal since the yellow light was added more than a century ago By JEFF McMURRAY The Associated Press ...