Outdoor Lighting and Crime - Amper

Intent in two of the source documents. These shortcomings again appear to be of little
consequence for the immediate purpose.
Part or all of the drop in motor vehicle thefts in the 1990s appears to have been a result of
various measures stemming from political concern, such as increased attention to insurance
fraud, vehicle ‘rebirthing’ and anti-theft devices (eg Grabosky and James 1995, Section 14).
The Australian population is also plotted in Figure 1 using data from Lahmeyer (2002).
Missing data for some early years have been interpolated. Population data are shown because
they are readily available and because many of the social factors that might be thought to
encourage crime (eg housing density) seem likely to be related to the size of the national
population. Given the different character of the skyglow and population growth curves, it was
thought possible that correlations of each with crime data might indicate any relative
differences in degree of association.
Australian crime records are available for six of the years in the period 1890 to 1902, but they
are given only as offences against the person and offences against property. Public
drunkenness is not included here as it is no longer a crime. The total rate of violence and
property crime for this period in Australia fell from about 11 per 1000 to under 7 (Graycar
2001). A roughly equivalent total rate of violence and property crime in the last years of the
twentieth century is over 60 per 1000, ie about 7 times greater. The total rate for all crime in
Victoria was about 40 per 1000 in the first half of the twentieth century, doubling from 1945
to 1955 and trebling by 1975, reflecting an Australia-wide pattern (Walker (2002), hard copy
version cited by DCPC (2002) p 11).
Over the twentieth century, the Australian population grew by a factor of about 5. The
increase in natural plus artificial outdoor light flux in the Melbourne metropolitan area in that
time is about 30 times, less if moonlight is included in the natural flux, or more if moonless
overcast nights are considered. It is more again if the peak ambient illuminance in large city
centres is considered, or less for the typical ambient illuminance in the outer suburbs. Crime
rate growth (day plus night) is obviously correlated both with lighting growth and with
population growth over decades. Neither appears to be a markedly better correlate than the
other.
Discussion of causality would be premature at this stage. Readily available Australian crime
data appear to be of insufficient quantity and quality to get much further with this line of
investigation. In the absence of reliable crime data for the earlier part of the twentieth
century, attention has been directed to other countries with better records.
2.3.2 England and Wales
Population data for 1900 through 1997 from the House of Commons library (Hicks and Allen
1999) for England plus Wales are plotted in Figure 2. The population graph was extended by
linear extrapolation back to 1898 and on to 1998. Total crime data from the Home Office
(2002b) for 1898, 1899, and to 2001 (retaining the pre-April 1998 counting rules) have also
been used to extend the graph. The crime data set covers a much longer span than that for
Australia in Figure 1.
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