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DAVID WILLIAMS: Smart traffic signals pave way for better driving in connected world

David Williams

David Williams

In today’s technological age we describe almost everything as a smart device, i.e., smart phones, smart TVs, smart cars, smart watches, and so on.

But what do we mean when we say “smart traffic signals”? Does it mean the same thing? Well, yes, it does, in many ways. Basically, when we say something is smart, we are referring to how a device interacts with us people.

MDOT Traffic Resources
A great example of this is found at www.mdottraffic.com. This website created by the Mississippi Department of Transportation has much to offer: “MDOT has free resources to help you deal with traffic. Access what you need to know about road conditions, construction projects, accidents, weather alerts and more.” You can sign up for traffic condition text alerts or email alerts customized for your daily commute. You can also view live feeds via cameras located throughout the state. And, yes, there is an app for this, which you can conveniently download to your smart phone. There is also a feature that allows you to personalize 511 for traffic information. All of this information is displayed on a state map and is user-friendly, such that you can zoom in and out of any area in the state, pick traffic cameras to view to visually determine levels of congestion and read a variety of alerts.

The smart part is relaying this information to people so they can make travel decisions based on existing conditions. This information is heavily used by other forms of media such as radio and television newscasts to disseminate traffic information to the public. Police, medical and emergency responders also use this system to enhance their ability to respond to any emergency in the state. Read more about Intelligent Traffic Systems on the mdot.ms.gov website.

Smart Intersections Drive Our World
The signalized intersections that we drive through every day constitute another form of smart traffic signal. These traffic signals are designed to detect traffic moving toward the intersections and adjust the signals’ timing to volumes of traffic. Vehicle detection is achieved in a variety of ways; the most common is inductive loops of wire imbedded in the asphalt. These detect vehicles that pass through magnetized fields created by the loops of wire. Other forms of detection include camera, radar and similar technology.

The computers or controllers at the intersections determine how much “green time” to give to each approach – or set of lanes – the intersection. Timing plans are created by engineers based on existing or historical traffic counts. These timing plans change by time of day and day of week, and even for special events such as football games, school times, holidays and large events, like a multi-day rodeo or fair being held in town, that create an irregular influx of traffic.

Smart traffic signals can also detect an approaching emergency vehicle such as a fire truck or an ambulance. They give the emergency vehicle priority through intersections—and they give extended green time ahead of the emergency vehicle, allowing traffic in front of the emergency vehicle to safely move out of the way. Coordinated systems of traffic signals can work together to move traffic along a corridor in a coordinated fashion. These systems can stagger the beginning of the green phases so that a traveling vehicle can proceed down the street at the proper speed without having to stop at any of the traffic signals. The success of a traffic signal system or even of a single traffic signal depends greatly on signal maintenance.

Traffic Signals See & Feel Traffic
A traffic signal “sees” or “feels” traffic through detection; if the detection doesn’t work properly, then the traffic signal has no way of knowing what traffic is there and must operate according to timed settings. You’ve seen it a million times when you waited at a red light with an empty thoroughfare before you. Without a detection system, unnecessary delays in traffic are inevitable. It is important to report any problems you see with traffic signals to the local governing agency, whichever it may be. With all of the signalized intersections in metro areas, it is a great help to the cities and the public if we report problems that could otherwise go unnoticed for a while. Doing this can greatly improve our traveling experience and make our paths safer and smarter

David Williams, P.E. is Project Manager – Transportation Division forWaggoner Engineering. Engineered For Success is an occasional column on the latest trends, issues and perspectives facing the engineering, economic development and project management industry, written by members of the Waggoner Engineering team.


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