Outdoor Lighting and Crime - Amper

account for the strong positive correlations observed. For night and day combined, the
indirect effects of all outdoor lighting combined with any direct effects appear to increase the
total crime rate more than they reduce it.
Records of events in which imposed darkness inhibited crime clearly indicate the action to be
causal and a mix of direct and indirect effects. This is strong evidence against the notion that
crime and lighting are unconnected quantities merely growing concurrently because of
separate reliance on economic conditions or similar variables.
9.8 TESTING THE HYPOTHESIS
The lighting, commerce and crime hypothesis was tested by examining the crime rate in all
cities of Australia, Canada, England and the USA for which satellite measures of total upward
light energy losses had been published. For England and the USA (the two largest data sets),
statistically significant positive correlations were found between crime data and city upward
light energy loss. A non-significant positive trend was found for Canadian cities. The
Australian crime data were sparse and internally inconsistent, and the analysis was
indeterminate. The highest correlations were found when the light energy loss was on a per
person basis for the USA data and on a per unit area basis for the English data. No reason
was apparent for why this difference existed but possible explanations were suggested.
Regardless, the evidence is interpreted as providing strong support for the hypothesis, and as
discrediting the common belief that lighting helps prevent crime.
The hypothesis was tested in two of Melbourne’s main streets for which the closest street
addresses had been recorded for day plus night serious drug crime arrests. The hypothesis
allowed a prediction that the arrest locations would be brightly lit at night. Illuminance
measurements along these streets indicated that the arrest locations were indeed clustered
where there was bright commercial and public lighting at night. Data constraints imposed by
the police tended to obscure the hypothesised relationship. Statistical analysis indicated that
the arrest locations were reliably in the more brightly lit locations in one of the two streets
examined, and reliably avoided lighting extremes in the other. This supports the indirect
causal role of lighting, the central feature of the hypothesis. No obvious connection was
apparent between the crime locations and resident population or population density along the
streets. Some of the locations were recognisable ‘people magnets’ such as game parlors and
fast-food shops.
Measurements of illuminances were made at Melbourne railway stations after formulation of
the hypothesis. They were found to be lit to daylight levels, as promised by politicians years
earlier in a plan to reduce crime. Subsequently, a Melbourne newspaper devoted several
pages to the increasingly high rate of crime in the rail system, especially at the stations. This
is claimed as a successful qualitative prediction.
9.9 LIGHTING AND THE FEAR OF CRIME
Outdoor lighting tends to allay the fear of crime. Its use in moderation for this purpose in
combination with other reasons such as mobility safety can be justified as long as actual crime
or the risk of actual crime is not thereby increased significantly, and subject also to
environmental constraints. This appears likely to pose a trade-off dilemma in practice.
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