Outdoor Lighting and Crime - Amper

objectionably large reduction, particularly if the data in Figure 9 are in a range where the
underlying curve is descending relatively steeply.
5.5 MISCELLANEOUS ASPECTS OF OUTDOOR LIGHTING AND
CRIME
5.5.1 Baltimore studies
As with many other large cities in the US and elsewhere, artificial skyglow above Baltimore
is severe: only the 20 brightest stars are now visible to the unaided eye on any given night,
which is just 0.7% of the 2700 that would be visible naturally (Task Force 2002). This
problem is growing, partly because of continuing urban sprawl. Ironically, this sprawl has
been monitored recently using upward light emissions measured by satellite (NASA 2002).
The city is of interest here because it has the third highest UCR crime rate and the worst
Morgan Quitno ranking (312 out of 315) of the 21 US cities in Table 5, despite the very large
sums spent on urban renewal in Baltimore since the 1970s.
Baltimore stands out particularly on Figure 10, where it has the highest crime score. The
satellite light energy loss value is not unusually large, judged against the other cities in the US
data set. If excessive light is indeed the problem or a substantial part of it, the position of the
Baltimore data point on the horizontal scales of Figures 7, 9 and especially 10, is too far to the
left for the amount of crime experienced. This anomaly could be a result of the city being
brightly lit in the high crime areas and quite moderately lit in the larger remaining areas.
Furthermore, if many well-shielded luminaires are in use, the shielding would certainly not be
a pro-crime problem in itself but it would reduce the satellite data value relative to the amount
of light at the ground.
The continuing high crime problem in Baltimore led Schumacher and Leitner (1999) to study
displacement of crime (burglary) from parts of the renewed areas. Increased numbers of
security personnel in these areas appeared to have encouraged the displacement. Overall,
outdoor lighting increases undoubtedly played a part in attracting people into the city, where
the combination of more potential victims and the increased prosperity of the area must have
increased the opportunity and motivation for crime. Despite the weakness of the case for
increased lighting reducing crime, Schumacher and Leitner only cited references claiming this
case and did not mention any doubts or contrary views. Their paper contains no information
on how their computer model weighted any of the following: increased presence of security
personnel, ‘improved’ street lighting and increased numbers of pedestrians and bystanders
providing increased casual surveillance and increased opportunity for crime. It is suggested
that this and similar models should be run with increased lighting set to increase crime. Such
models may be useful in investigating delays between lighting increases and hypothesised
consequent increases in crime.
5.5.2 Displacement and diffusion
Displacement of crime or diffusion of crime reduction benefit to surrounding areas is
sometimes reported as a direct spatial effect of the treatment in studies of outdoor lighting
changes and crime. As displacement, no effect and diffusion between them appear to cover
all possible outcomes in nearby areas, they could be rationalisations of the whole gamut of
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