© 2025 Connecticut Public

FCC Public Inspection Files:
WEDH · WEDN · WEDW · WEDY
WEDW-FM · WNPR · WPKT · WRLI-FM
Public Files Contact · ATSC 3.0 FAQ
Play Live Radio
Next Up:
0:00
0:00
0:00 0:00
Available On Air Stations

Red Light, Green Light: The Science Behind Traffic Signal Systems

Horia Varlan
/
Creative Commons

Here's a riddle for you: What's green and yellow, but most often red?

...Give up? It's a traffic light -- you know, those things you hit on your way into the office each morning. 

But how do they work? And why don't they ever seem to be synched up? 

This hour, we explore the science behind traffic light programming. We hear from engineers and experts in Connecticut and Utah. We also find out how new "smart" signals are improving traffic flow in Pittsburgh, Pennsylvania. 

And later, if you've ever gotten turned around while driving through downtown New Haven, you’re not alone. We learn how converting from a one- to two-way street system could make the city safer and easier to navigate.

GUESTS:

  • Jack Carey - Associate at Fuss & O’Neill, an engineering consulting firm in Manchester, Connecticut
  • Lisa Miller - Traveler Information Manager at Utah Department of Transportation
  • Stephen Smith - Research Professor in Robotics at Carnegie Mellon University
  • Doug Hausladen - Director of Transportation in New Haven; Acting Executive Director of the New Haven Parking Authority

Join the conversation on Facebook and Twitter.

John Dankosky and Chion Wolf contributed to this show.

The independent journalism and non-commercial programming you rely on every day is in danger.

If you’re reading this, you believe in trusted journalism and in learning without paywalls. You value access to educational content kids love and enriching cultural programming.

Now all of that is at risk.

Federal funding for public media is under threat and if it goes, the impact to our communities will be devastating.

Together, we can defend it. It’s time to protect what matters.

Your voice has protected public media before. Now, it’s needed again. Learn how you can protect the news and programming you depend on.

SOMOS CONNECTICUT is an initiative from Connecticut Public, the state’s local NPR and PBS station, to elevate Latino stories and expand programming that uplifts and informs our Latino communities. Visit CTPublic.org/latino for more stories and resources. For updates, sign up for the SOMOS CONNECTICUT newsletter at ctpublic.org/newsletters.

SOMOS CONNECTICUT es una iniciativa de Connecticut Public, la emisora local de NPR y PBS del estado, que busca elevar nuestras historias latinas y expandir programación que alza y informa nuestras comunidades latinas locales. Visita CTPublic.org/latino para más reportajes y recursos. Para noticias, suscríbase a nuestro boletín informativo en ctpublic.org/newsletters.

The independent journalism and non-commercial programming you rely on every day is in danger.

If you’re reading this, you believe in trusted journalism and in learning without paywalls. You value access to educational content kids love and enriching cultural programming.

Now all of that is at risk.

Federal funding for public media is under threat and if it goes, the impact to our communities will be devastating.

Together, we can defend it. It’s time to protect what matters.

Your voice has protected public media before. Now, it’s needed again. Learn how you can protect the news and programming you depend on.

Connecticut Public’s journalism is made possible, in part by funding from Jeffrey Hoffman and Robert Jaeger.