They devised a set of cameras and sensors to be mounted on top of city-owned vehicles, such as police cars, night buses or garbage trucks which regularly cruise the city's streets. Tagging it with GPS data, the sensor pack uses digital cameras and sophisticated software to distinguish between streetlights and other sources of illumination, and even to estimate the height of each lamp. Other sensors measure the exact level of illumination to determine if lights are failing, or if there are dark areas between lights which would indicate a possible lamp outage or a need for an additional light pole.
The idea is to build up a comprehensive listing or map of where street lamps are as city-owned vehicles drive-by, offering a more up-to-date map than what infrequent and expensive manual surveys could offer. Such a sensor-based approach would pin-point failures and in the long run, would provide urban planners with a track record of how LED-based upgrades perform compared to mercury lamps yet to be replaced.
The height indication is also critical in order to send the appropriate lift truck when going out on a lamp-replacement mission, saving on time and money.
Field tests were carried out in four cities including Cambridge, Massachusetts; Malaga and Santander in Spain; and Birmingham, UK, using portable equipment mounted on the roofs of economy rental cars or vans.
Although the research was aimed at improving streetlight maintenance, the researchers expect that same concept (combining precision mapping and camera-based information capture) could be used to track other aspects of urban infrastructure, including potholes and other issues in the streets themselves, the location and condition of signs and signals, and so on.
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