Lighting, Crime, & Roadway Safety
It is true that we need street lighting for crime prevention and roadway safety - to a certain extent. Simply adding more or brighter lighting doesn’t necessarily make the area safer. Light fixtures should be chosen and placed intentionally, keeping in mind that the goal is to improve visibility - not to blast light in every direction.
Crime
The belief that increased street lighting and crime reduction are related is widespread, but there are a number of studies that disprove this idea. A research report for the National Institute of Justice concluded that “we can have very little confidence that improved lighting prevents crime” [1]. Likewise, a 2015 study on the effect of reduced street lighting on crime at night reported that “there was no evidence that reduced street lighting was associated with crime” [2]. The Chicago Alley Lighting Project concluded that there did not appear to be a reduction of crime in alleys where lighting was increased [3]. In fact, based on a 2015 study in England and Wales, dimming lights may actually contribute to a reduction in crime. This study also concluded that “local authorities can safely reduce street lighting, saving energy costs and reducing carbon emissions, without impacting negatively on street collisions or crime” [4].
These studies show that crime rates are not dependent on the amount of street lighting in an area. This means that we can reduce light pollution by installing fewer street lights or dimming lights overnight without having a negative impact on crime rates.
Roadway Safety
There is little evidence that increased street lighting has a positive impact on roadway safety. In fact, glare from intensely bright and unshielded lights can actually decrease visibility, making it harder to see roads and hazards at night. In a 2015 study, researchers concluded that there was no evidence that light pollution reduction strategies were associated with an increase in road collisions [4].