Abstract
Many local authorities in England and Wales reduced street lighting at night using one of four street lighting adaptation strategies: switch off, part-night lighting, dimming, and white light. The effect of these changes on road traffic collisions and area-level crime was assessed.
Intervention overview
In the United Kingdom (UK), there are national guidelines and professional standards that guide the choice of street lighting installed by local authorities on roads. However, ultimately these local authorities have autonomy allowing them to choose the most appropriate lighting to implement. 62 local authorities in England and Wales made changes to street lighting to increase energy efficiency, and in turn reduce costs and their impact on climate change.
Four street light adaptation strategies were introduced: switching lights off permanently; reducing the number of hours that lamps are switched on at night; reducing the power or output of lamps, or dimming; and replacing traditional sodium lamps with LEDs (white light).
There were public concerns about the negative effects that could impact public health, namely that these changes may increase crime and traffic collision rates. This study was undertaken to evaluate the impact of the lighting strategies on such outcomes.
Outcomes
The greenhouse gas reduction was not measured in this study. However, for all four adaptation strategies that were used (switch-off, part-night lighting, dimming, and white light), there are clear and well-established energy efficiency benefits.
There was no evidence that any street lighting adaptation strategy was associated with a change in night-time traffic collisions in any area in the study. There was also no association between the number of area-level crimes and two of the strategies used, switch-off or part-night lighting. There was some evidence that, in areas where dimming and white light were used, there was a reduction in the number of area-level crimes recorded.
In a related study, switching lights off was strongly associated with a reduction in the level of night-time theft from vehicles at street-level, but an increase in adjacent roads where street lighting remained unchanged. This indicates that although area-level crime may not be affected, at street-level, crime may be displaced to better-lit adjacent streets (Thompson, 2022).
Feasibility and potential impact of scale-up
The analysis undertaken in this study was only possible because two large publicly available datasets were available that contained information allowing for spatial comparison between street lighting strategy and crime rates and road traffic collisions. Therefore, having monitoring structures or systems in place can be a valuable source of data allowing for such exploration of associations.
There is evidence in the literature suggesting that increased street lighting improves road safety or results in crime reduction (Beyer and Ker, 2009; Welsh and Farrington, 2008). However, there was no empirical evidence on whether a reduction of street lighting has negative effects on crime and road collisions. Therefore, although an increase in street lighting may reduce negative outcomes in some settings, this study has shown that the reduction of street lighting does not necessarily cause higher levels of crime or accidents.
There could also be some health or well-being benefits from reduced street lighting such as improved sleep and being able to see the night sky due to reduction in light pollution. Exposure to light at night can interrupt the normal circadian rhythm, resulting in negative physiological and behavioural consequences (Navara and Nelson, 2007). For example, one study showed that obesity may be associated with exposure to light at night due to disruption of sleep and the circadian rhythm (McFadden et al., 2014). Therefore, in addition to energy efficiency and its positive impact on climate change, the additional benefits to reduced lighting on human health warrants further investigation.
References
Academic profile / relevant organisation’s page
- Steinbach R, Perkins C, Tompson L, Johnson S, Armstrong B, Green J, Grundy C, Wilkinson P, Edwards P. The effect of reduced street lighting on road casualties and crime in England and Wales: controlled interrupted time series analysis. J Epidemiol Community Health. 2015 Nov 1;69(11):1118-24.
Supplementary information
- Beyer, F. R., & Ker, K. (2009). Street lighting for preventing road traffic injuries. Cochrane database of systematic reviews, (1).
- Welsh, B. C., & Farrington, D. P. (2008). Effects of improved street lighting on crime. Campbell systematic reviews, 4(1), 1-51.
- Navara, K. J., & Nelson, R. J. (2007). The dark side of light at night: physiological, epidemiological, and ecological consequences. Journal of pineal research, 43(3), 215-224.
- McFadden, E., Jones, M. E., Schoemaker, M. J., Ashworth, A., & Swerdlow, A. J. (2014). The relationship between obesity and exposure to light at night: cross-sectional analyses of over 100,000 women in the Breakthrough Generations Study. American journal of epidemiology, 180(3), 245-250.
- Tompson L, Steinbach R, Johnson SD, Teh CS, Perkins C, Edwards P, Armstrong B. Absence of Street Lighting May Prevent Vehicle Crime, but Spatial and Temporal Displacement Remains a Concern. Journal of Quantitative Criminology. 2022 Mar 30:1-21.
Contact
- Dr. Rebecca Steinbach, London School of Hygiene & Tropical Medicine, Email: [email protected]