Safe Streets: Traffic control devices


When you head out the door to drive to work or school, you have a good idea exactly how many minutes it takes you, on a good day, to get where you're going.

But what happens when the technology that keeps traffic flowing gets fouled up? That could result in delays and even cars taking risks they shouldn't take.
In today's Safe Streets report, we look at the brains behind the thousands of intersections managed by highly sophisticated traffic controls.

There are 1,150 intersections in Indianapolis that all depend on big metal boxes on the street corner.

Traffic Systems Engineer Nathan Sheets opened up what's called a "traffic signal cabinet" to show us what keeps traffic moving.

"This right here is our signal controller," Sheets said, pointing to a blue box. "What we would call the brains of the signal cabinet right here."

The blue box with buttons and a digital display sits at the center of all the electronics. "What this essentially does is allow us to input different timings for signals," Sheets explained. "It has an internal time clock that knows what day of the week, what the specific day is and the time, and that way we can generate timing patterns."

When it works, traffic moves smoothly, but inevitably some of these boxes are thrown off, or break down.

Sheets says it's "just like your clock at home. If there's a lightning strike or a power surge sometime that clock gets set to 12:00 midnight and so the day of the week and time can be off."
That can foul up carefully-timed traffic patterns and lead to traffic backups.

Sitting at an intersection, you may wonder how a traffic light knows you're at the light. Cars pass over an octagonal outline in the street that senses the weight of the car.  The wires then pass through the blue box, which sends that signal to the traffic signal cabinet on the corner, in a matter of seconds, the light changes.
Cars we observed waited about 30 seconds before the induction loop triggered the green light.
Sheets told us, "Because we have these detection loops, sometimes the loops fail for various reasons."
When that happens and you notice a delay, the Indianapolis Department of Public Works says contact the city.

Plus, these links can help you deal with situations on the road:

RequestIndy is an online portal that allows residents to report problems in their neighborhoods such as traffic issues, high weeds and grass, potholes and stray animals.  The first-of-its-kind portal for the City of Indianapolis uses GIS mapping technology to provide a user-friendly means of connecting with the city.

The RequestIndy app for iPhone/iPod
RequestIndy can be used to enter more than 30 of the most commonly requested services. RequestIndy is fully-integrated with the city's enterprise-wide service systems for each city department so requests are routed directly to the folks who can resolve the issue.
Or you can call the Mayor's Action Center at 317-327-4MAC (4622)

Safe Streets, Part I

Safe Streets, Part II