NMA E-Newsletter #133: Adaptive Signal Control, a Camera System that Actually Helps?


For better or for worse, cameras are all over our streets and highways. Some systems, such as red-light cameras, are used simply to scrutinize drivers for questionable “violations” in order to generate revenue with a minimum of inconvenience to the state.

But some camera applications actually benefit drivers. Camera systems that provide traffic information to motorists, in order to help them plan more comfortable and efficient routes, for example, seem valuable and fairly unobjectionable.

One significant camera application currently in use is “adaptive signal control,” which employs cameras to provide a view of traffic in order to change signal-light timing to ease congestion and avoid unnecessary delay. In other words, the idea is to figure out if there are cars at an intersection at any given time, in order to change the signals more efficiently.

In the old days, that involved cutting back the pavement a few inches at the approach point of an intersection and installing a wire “induction loop” just below the surface. The presence of a vehicle there triggers an electronic signal to be processed by a remote controller for changing the timing of the traffic signal.

But nowadays, increasingly the job is done by camera, and there is no need for ripping up the road, with its higher cost and creation of traffic delays. The cameras, though out of the way of motorists, register an image of the traffic and relay it to the processor.

According to the U.S. Department of Transportation Research and Innovative Technology Administration (RITA) 2009 Application Overview, 19 states and the District of Columbia used adaptive signal control as of 2007. (A request by the NMA for more recent data yielded no response from RITA.)

But even useful camera applications have downsides, and carry a risk of being used improperly, in the seemingly inevitable process of “mission creep.” In New York, which recently installed a new adaptive signal control camera system, some are raising privacy concerns, and wondering whether the cameras will be used as enforcement tools against motorists.

The key is to remember that not all camera applications are in the best interests of motorists or citizens in general. There is bound to be some “upside” to any proposed camera application, but we need to be critical and weed out schemes that actually hurt motorists. ♦

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