Lighting : LIGHTING-February-2017
24 LIGHTING MAGAZINE | February/March 2017 February/March 2017 | LIGHTING MAGAZINE 25 CAN YOU DRILL A LITTLE DEEPER INTO HOW INCREASING LIGHT AT NIGHT CAN LEAD TO MORE CRIME? There is currently not much evidence on this, but interviews with criminals have indicated a simple answer: it’s because they can see more easily. Absolute darkness hinders or deters criminal acts. At the other extreme, changes in daylight levels have little effect on visual performance and do not appear to affect crime. Outdoor artificial lighting levels lie between these extremes so it appears that increased lighting typically aids criminals more than it deters them. SO HOW DO WE ACHIEVE A GOOD BALANCE? HOW CAN LIGHTING BE USED AS A PREVENTIVE AND CORRECTIVE MEASURE AGAINST CRIME? Basically we need light at night for mobility safety, wayfinding and reducing the fear of crime. But it comes at a cost of more actual crime. There is no known way around this. All we can do is to minimise this adverse effect by using the minimum amount of light, if any, for the particular circumstances. I’ll give a couple of examples: Some schools in Washington State were able to reduce vandalism almost to zero by reducing site lighting after 10:30pm. In San Antonio, the school district cut their bill for vandalism from US$160,000 per year, to US$41,000 by turning the lights off at night. WHAT ABOUT THE USE OF STRATEGIC LIGHTING FOR CCTV CAMERAS? Extra lighting often installed with CCTV must tend to increase crime. Typically, CCTV installations show no crime reduction, but occasionally their recordings provide useful evidence. After the murder of Jill Meagher in 2012, Moreland Council in Melbourne ignored my advice and spent over two hundred thousand dollars on security lights and cameras. It’s made absolutely no difference to the crime rate over the last two years. The Council recently decided against removing the cameras. WHAT’S THE SOLUTION? Modern society couldn’t exist without light at night, but we need to be smarter in using it. Lighting strategies may need to be location specific, such as the possibility of using movement sensors. But generally we need to use minimal lighting without glare, light trespass, direct uplight, harsh shadows or steep light/dark transitions. There are also compelling reasons to minimise blue-light content, but that’s another story. Until the lighting and crime issue is better understood and quantified, no more security lighting or other lighting supposedly for crime- prevention should be installed. In the meantime, funding should be redirected to rectify existing outdoor lighting that is economically, environmentally or sociologically inappropriate. DR BARRY CLARK Dr Barry Clark started making his own astronomical telescopes as a teenager. After qualifying as a Mechanical Engineer, he did a BSc in physics and began working in a Defence optical laboratory. Masters and PhD degrees in physiological optics followed. His interest in vision led to a research career in environmental effects on human performance, particularly aircrew vision. His published output of well over a hundred journal papers and technical reports covers many fields including optics, photometry, spectrophotometry, radiometry, colorimetry, lighting, biological and behavioural effects of artificial light at night, vision and eye protection. He has appeared as an expert witness in several air accident enquiries, arbitration proceedings and planning tribunals. He has represented the Department of Defence on several international and Australian standards committees. In retirement, he has been an optics consultant and an adjunct associate professor. He is currently the Director of the Outdoor Lighting Improvement Section of the Astronomical Society of Victoria Inc and a committee member of the Victorian Chapter of the International Dark Sky Association. He is also an honorary associate of Museum Victoria in the Great Melbourne Telescope reconstruction project. Lighting and crime has been one of his research topics in retirement. Figure 3. These luminaires use metal halide lamps in reflector fixtures which focus the lamp’s output downward. This redirects the upward and sideway light to where it is needed, resulting in higher efficiency, allowing the use of lower wattage lamps while reducing the glare. Modern society couldn’t exist without light at night, but we need to be smarter in using it. Lighting strategies may need to be location specific, such as the possibility of using movement sensors.
Lighting December 2016