A team of researchers in Poland has designed a smart traffic sign that uses the Doppler Effect, a physics phenomenon, and video to detect everything from passing vehicle speed to road conditions. Unlike existing traffic sensors that simply record speed, these dynamic signs would warn drivers of impending accidents before they happen…
This acoustic doppler data is then further analyzed by something called an “acoustic vector sensor” (AVS) to create a more dynamic picture of traffic patterns…

While some doppler sensors use microwaves to make their measurements, which are susceptible to electromagnetic interference, the researchers say that their AVS uses passive monitoring and doesn’t emit any signals that could be manipulated. More importantly, their sensor also enables the smart traffic signs to collect information about weather and the road condition (for example, how slick a road is), making its estimation of traffic hazards even more accurate.
More>>