With lighting systems that adjust to traffic volumes, the most common approach involves sections of lights that regulate to overall traffic density.
“This approach is well suited to highways and trunk roads that are busy at most times of the night.”
Chintan Shah,CEO
San Francisco trialled three such systems last year and the county of Suffolk in eastern England has plans to implement traffic-sensitive lighting of this kind on as many as ten thousand LED streetlights by mid 2017. But for quieter areas, such as residential streets and ring roads, sensing technology is now available to produce lighting that only brightens when the presence of a car, cyclist or pedestrian is detected and only illuminates the immediate surroundings.
By TrafficTechnologyToday
Published in TrafficTechnologyToday February/March 2016 edition
From http://viewer.zmags.com/publication/6eacd0e8#/6eacd0e8/1