How many cities have a detailed listing with comprehensive information about the current condition of their public street lighting? Probably, only very few cities. The exact location and height of every light point, the expected lifetime, performed illumination time, type of product, type of light source, date of construction, energy demand, and further information can be included. Depending on the size of the city, the development and maintenance of a citywide database of the entire street lighting is extremely time-consuming and costly if it is conducted by authorized inspectors.
“The way we measure street lighting is still very primitive,” Kumar says
Furthermore, fast reactivity on, for example, burned-out lights or the maintenance of light points with an uncertain location and height for the right lift truck results in inefficiency. Are there places where lights are failing? Are there dark areas even if the street lighting is working as intended? Are there places which need additional or less light poles?
It seems there is a more advanced method according to researchers at MIT’s Department of Mechanical Engineering. As described in a recently published study, called Urban Street Lighting Infrastructure Monitoring Using a Mobile Sensor Platform, it is possible to automate the inspection of street lighting with drive-by monitoring.
Monitoring street lighting with car-mounted cameras and sensors
It reminds us of how Google Street View has been created. With digital cameras, light measurements, GPS and sophisticated software, the researchers distinguish between streetlights and other sources of illumination. They also were able to estimate the height of each lamp. By measuring the exact level of illumination, it was possible to determine dark areas and possible lamp outages. In the end, an accurate map and a database have been created which can be send in real time to any position.
An upgrade of old lighting technology to long-lasting LED is much more efficient with this monitoring system. “By comparing quantitative before-and-after data collected by the automated system, the improvements could be analyzed with great accuracy.” MIT states.
The researchers suggest mounting the equipment on city-owned cars, like police cars, buses, or garbage trucks, instead of buying a new fleet. Four field tests have been carried out in Birmingham (UK), Cambridge (Massachusetts) and Malaga and Santander in Spain. After each of these tests, Kumar says, “we would disassemble our entire project, pack it up in a suitcase, and get customs clearance” to move on to the next test.
“One interesting aspect of this work was the use of cameras to estimate the heights of the street lamps. … This type of information would be extremely useful for rapid inventory management,” says Andrew Smyth, a professor of civil engineering and engineering mechanics at Columbia University, who was not involved in this work. “With the general trend to more efficient and controllable LED street lighting systems, an improved knowledge of the current inventory and its effectiveness is extremely valuable. [This information can be used to not only] improve design of entirely new street lighting configurations but also assess the current performance of the existing systems, which may be under- or over-lighting in places.”