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NIHR Signal Reducing street lighting doesn’t lead to more road traffic accidents or crime

Published on 12 October 2015

doi: 10.3310/signal-000131

This NIHR study found that reducing or adapting street lighting was not linked to more road traffic accidents or crime in the UK. Many local authorities have changed their street lighting in recent years – switching off entirely, switching off for part of the night, dimming, or changing to energy efficient LED bulbs – to save money and meet local carbon emission targets. There was concern from the public and media that road traffic accidents and crime might rise as a result, but this NIHR-funded study analysing large local authority datasets provided evidence that this was not the case. The evidence had limitations and street lighting remains important to many residents. Therefore the impact of changes to lighting still needs to be carefully assessed before implementation and monitored afterwards.

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Why was this study needed?

In recent years many local authorities in England, Wales and Northern Ireland have changed street lighting provision in an effort to save money and reduce carbon emissions. Different approaches have been tried: turning off some street lighting entirely, reducing how long street lights are on, dimming street lights, or replacing bulbs with more efficient LED - “white lighting” - alternatives. There has been public and media concern that the street lighting cutbacks might increase road accidents and crime, but there is no consistent evidence justifying the concern. The NIHR funded this study to investigate the impact of changes to street lighting provision on road casualties and crime across local authorities in England, Wales and Northern Ireland.

What did this study do?

This study used data from 62 out of 174 English and Welsh local authorities on the type of street lighting changes made, the location of affected lighting and the date changes were introduced. Traffic collision data came from the UK’s official Department for Transport dataset (STATS19) and included dates, times, locations and details of casualties. Crime data came from the national Police website, including the type of crime, date (year/month) and geographical location. This publicly-available police crime data does not give precise locations or times of crimes, so the analysis was based on crimes considered most likely to occur at night-time: burglary, theft of (or from) a vehicle, robbery, criminal damage and violence, including sexual assault. The authors used this information to calculate the number of road traffic collisions and crimes in particular areas, and looked for any statistically significant associations with changes to street lighting over a 13 year period. There was no comparison before and after street lighting changes were introduced on individual roads, rather they looked at the overall trend over time in an area.

What did it find?

  • The 62 included local authorities often tried more than one change to street lighting: five switched off lights all night (8%), 30 tried switching off part of the night (48%), 40 dimmed lights (65%), 52 used new lower energy “white lighting” (84%). The number of local authorities introducing changes rose steadily from 2009 onwards.
  • There was no statistically significant association between night-time road traffic collisions (either the number of collisions or their seriousness) and changes to street lighting.
  • Between 2000 and 2013 there were 161,049 night-time road traffic collisions, 19% of the total. Of these, 0.7% (1,202) occurred on roads where lights had been switched off, 4% (5,670) where part-time lighting was in place, 7% (11,634) where there was light dimming and 8% (12,423) were on roads with “white lighting”.
  • There were no statistically significant associations between the number of crimes and any changes to street lighting provision.
  • Across the 62 local authorities from 2010-2013 there were 581,837 burglaries, 475,657 thefts of (or from) a vehicle, 67,470 robberies, 486,367 criminal damage offences and 730,280 violent offences.

What does current guidance say on this issue?

There are national guidelines and professional standards on street lighting available from the British Standards Institute and Institution of Lighting Professionals. However, local authorities are not bound by these and set their own street lighting policies based on their assessment of what is required.

What are the implications?

This study suggests local authorities who have changed their street lighting do not appear to have increased crime or road collisions.

The evidence has limitations though, meaning we shouldn’t assume this is a closed case. For example, it only included data from a third of eligible local authorities across England, Wales and Northern Ireland, so may not be nationally representative. Crime data is incomplete and under-reporting means the results could be subject to bias. It did not take account of avoidance behaviour due to change in lighting, for example, people might avoid dimly lit streets at night out of fear. The study did not consider wider factors affecting the rate of road collisions or crime, such as road safety initiatives or crime prevention. The impact of lighting changes was assessed by comparing areas with lighting changes to those without. It did not compare crime or accidents before and after lighting changes on the same road. This leaves open the possibility that street lighting does have an impact, but was not picked up using this method.

The results reinforce the need for local authorities to base decisions on street lighting on a thorough risk assessment of the potential impact on road collisions and crime. Furthermore, once street lighting modifications are introduced, their impact should be monitored to ensure there are no negative consequences, and to provide reliable data for future study.

Citation

Steinbach R, Perkins C, Tompson L et al. 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:pii.

Full HTA report: Perkins C, Steinbach R, Tompson L, et al. What is the effect of reduced street lighting on crime and road traffic injuries at night? A mixed-methods study. Public Health Res. 2015;3(11).

This project was funded by the National Institute for Health Research Public Health Programme (project number 11/3004/02).

Bibliography

British Standards Institution. BS 5489 Code of practice for the design of road lighting: lighting of roads and public amenity areas. London: British Standards Institutions; 2013.

Department for Transport. Road Safety Data. London: Department for Transport; 2014.

Green J, Perkins C, Steinbach R et al. Reduced street lighting at night and health: a rapid appraisal of public views in England and Wales. Health Place. 2015 Jul;34:171-80.

Home Office. Crime and policing in England, Wales and Northern Ireland. London: Home Office; 2015.

Institute of Lighting Professionals. PLG 08: guidance on the application of adaptive lighting within the public realm: professional lighting guide. Rugby: Institute of Lighting Professionals; 2013.

Why was this study needed?

In recent years many local authorities in England, Wales and Northern Ireland have changed street lighting provision in an effort to save money and reduce carbon emissions. Different approaches have been tried: turning off some street lighting entirely, reducing how long street lights are on, dimming street lights, or replacing bulbs with more efficient LED - “white lighting” - alternatives. There has been public and media concern that the street lighting cutbacks might increase road accidents and crime, but there is no consistent evidence justifying the concern. The NIHR funded this study to investigate the impact of changes to street lighting provision on road casualties and crime across local authorities in England, Wales and Northern Ireland.

What did this study do?

This study used data from 62 out of 174 English and Welsh local authorities on the type of street lighting changes made, the location of affected lighting and the date changes were introduced. Traffic collision data came from the UK’s official Department for Transport dataset (STATS19) and included dates, times, locations and details of casualties. Crime data came from the national Police website, including the type of crime, date (year/month) and geographical location. This publicly-available police crime data does not give precise locations or times of crimes, so the analysis was based on crimes considered most likely to occur at night-time: burglary, theft of (or from) a vehicle, robbery, criminal damage and violence, including sexual assault. The authors used this information to calculate the number of road traffic collisions and crimes in particular areas, and looked for any statistically significant associations with changes to street lighting over a 13 year period. There was no comparison before and after street lighting changes were introduced on individual roads, rather they looked at the overall trend over time in an area.

What did it find?

  • The 62 included local authorities often tried more than one change to street lighting: five switched off lights all night (8%), 30 tried switching off part of the night (48%), 40 dimmed lights (65%), 52 used new lower energy “white lighting” (84%). The number of local authorities introducing changes rose steadily from 2009 onwards.
  • There was no statistically significant association between night-time road traffic collisions (either the number of collisions or their seriousness) and changes to street lighting.
  • Between 2000 and 2013 there were 161,049 night-time road traffic collisions, 19% of the total. Of these, 0.7% (1,202) occurred on roads where lights had been switched off, 4% (5,670) where part-time lighting was in place, 7% (11,634) where there was light dimming and 8% (12,423) were on roads with “white lighting”.
  • There were no statistically significant associations between the number of crimes and any changes to street lighting provision.
  • Across the 62 local authorities from 2010-2013 there were 581,837 burglaries, 475,657 thefts of (or from) a vehicle, 67,470 robberies, 486,367 criminal damage offences and 730,280 violent offences.

What does current guidance say on this issue?

There are national guidelines and professional standards on street lighting available from the British Standards Institute and Institution of Lighting Professionals. However, local authorities are not bound by these and set their own street lighting policies based on their assessment of what is required.

What are the implications?

This study suggests local authorities who have changed their street lighting do not appear to have increased crime or road collisions.

The evidence has limitations though, meaning we shouldn’t assume this is a closed case. For example, it only included data from a third of eligible local authorities across England, Wales and Northern Ireland, so may not be nationally representative. Crime data is incomplete and under-reporting means the results could be subject to bias. It did not take account of avoidance behaviour due to change in lighting, for example, people might avoid dimly lit streets at night out of fear. The study did not consider wider factors affecting the rate of road collisions or crime, such as road safety initiatives or crime prevention. The impact of lighting changes was assessed by comparing areas with lighting changes to those without. It did not compare crime or accidents before and after lighting changes on the same road. This leaves open the possibility that street lighting does have an impact, but was not picked up using this method.

The results reinforce the need for local authorities to base decisions on street lighting on a thorough risk assessment of the potential impact on road collisions and crime. Furthermore, once street lighting modifications are introduced, their impact should be monitored to ensure there are no negative consequences, and to provide reliable data for future study.

Citation

Steinbach R, Perkins C, Tompson L et al. 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:pii.

Full HTA report: Perkins C, Steinbach R, Tompson L, et al. What is the effect of reduced street lighting on crime and road traffic injuries at night? A mixed-methods study. Public Health Res. 2015;3(11).

This project was funded by the National Institute for Health Research Public Health Programme (project number 11/3004/02).

Bibliography

British Standards Institution. BS 5489 Code of practice for the design of road lighting: lighting of roads and public amenity areas. London: British Standards Institutions; 2013.

Department for Transport. Road Safety Data. London: Department for Transport; 2014.

Green J, Perkins C, Steinbach R et al. Reduced street lighting at night and health: a rapid appraisal of public views in England and Wales. Health Place. 2015 Jul;34:171-80.

Home Office. Crime and policing in England, Wales and Northern Ireland. London: Home Office; 2015.

Institute of Lighting Professionals. PLG 08: guidance on the application of adaptive lighting within the public realm: professional lighting guide. Rugby: Institute of Lighting Professionals; 2013.

The effect of reduced street lighting on road casualties and crime in England and Wales: controlled interrupted time series analysis

Published on 30 July 2015

Steinbach, R.,Perkins, C.,Tompson, L.,Johnson, S.,Armstrong, B.,Green, J.,Grundy, C.,Wilkinson, P.,Edwards, P.

J Epidemiol Community Health , 2015

BACKGROUND: Many local authorities in England and Wales have reduced street lighting at night to save money and reduce carbon emissions. There is no evidence to date on whether these reductions impact on public health. We quantified the effect of 4 street lighting adaptation strategies (switch off, part-night lighting, dimming and white light) on casualties and crime in England and Wales. METHODS: Observational study based on analysis of geographically coded police data on road traffic collisions and crime in 62 local authorities. Conditional Poisson models were used to analyse longitudinal changes in the counts of night-time collisions occurring on affected roads during 2000-2013, and crime within census Middle Super Output Areas during 2010-2013. Effect estimates were adjusted for regional temporal trends in casualties and crime. RESULTS: There was no evidence that any street lighting adaptation strategy was associated with a change in collisions at night. There was significant statistical heterogeneity in the effects on crime estimated at police force level. Overall, there was no evidence for an association between the aggregate count of crime and switch off (RR 0.11; 95% CI 0.01 to 2.75) or part-night lighting (RR 0.96; 95% CI 0.86 to 1.06). There was weak evidence for a reduction in the aggregate count of crime and dimming (RR 0.84; 95% CI 0.70 to 1.02) and white light (RR 0.89; 95% CI 0.77 to 1.03). CONCLUSIONS: This study found little evidence of harmful effects of switch off, part-night lighting, dimming, or changes to white light/LEDs on road collisions or crime in England and Wales.

Local authorities are responsible for street lighting and have tried various ways to reduce street lighting at night. The policy is primarily driven by requirements to reduce costs and carbon emissions under the Climate Change Act 2008 but also with considerations of contributing to reductions in environmental light pollution. Technological innovations now allow greater control over the colour, intensity and switching on schedules of public lighting. The sorts of changes that have been tried include: removing, or switching off lanterns in street light columns (“switch off”); reducing the number of hours that they are switched on (“part-night lighting”); replacing sodium lanterns by white LED light; and dimming lanterns through centrally managed systems.

Switch off and part-night lighting result in dark streets which were once lit, at least for some of the night time hours and in theory could increase accidents and crime. The introduction of energy efficient lamps, or LEDs, can change the quality and colour of lighting (e.g. from yellow to white light). They do this without reducing visibility, so in theory white light might improve people’s ability to see and could also improve closed circuit television images, deterring certain types of crime.

Author commentary

The study findings suggest that local authorities who have reduced provision of street lighting over recent years have done so safely, without increasing road traffic casualties or crime.

Switching off lights at night may be considered as part of a local lighting adaptation strategy, providing that each area is carefully assessed by a qualified lighting professional, using a risk-based analysis.

Street lighting remains important to many urban and suburban residents, and some feel less safe walking alone in the dark. Changes to lighting will need to be managed carefully.

Dr Phil J Edwards, Senior Lecturer, London School of Hygiene and Tropical Medicine

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