Outdoor Lighting and Crime - Amper

Reduced incidence of crime should take precedence over reduced fear of crime. An
acceptable balance may be achievable with minimal ambient lighting of sufficient uniformity
and minimal glare. Where public lighting can be justified at all, only full-cutoff luminaires
should be used. Additional shields should be used routinely to shade nearby properties from
spill light. Further research is required on whether the colour of the light has any effect.
9.10 LIGHTING AS A ROAD ACCIDENT COUNTERMEASURE
Field evaluations with poor experimental design or funding by vested interests, or both, may
have had undue influence in forming conventional wisdom that road lighting is a night traffic
accident countermeasure. The installation of brighter lighting at accident-prone sections of
roads without adequate experimental controls invites false beneficial results because of the
effect of regression to the mean. The existence and size of any such beneficial effects on
traffic safety need to be reassessed. A substantial reduction in street lighting appears possible
with minimal, if any, adverse effects on traffic safety by banning tinted glazing in vehicles,
other than in a band at the top of the windshield. Such a ban may avoid a potential need to
reduce the lighting flux from individual vehicles, or to limit the number of vehicles on the
roads at night, or both.
9.11 OUTDOOR LIGHTING REDUCTION
Outdoor ambient light levels at night in many cities and towns appear to be too high for
crime, health, safety and environmental reasons and need to be reduced. The scope for
change is indicated by some cities having twenty or more times as much light than others in
terms of per person or per unit area. A citizen survey in a relatively dimly-lit city indicated
acceptability of the installed lighting. Substantial reductions in outdoor lighting are therefore
expected to be possible in many cases and to reduce or reverse the growth of urban crime and
the pressure for growth in police and criminal justice resources.
A maximum horizontal and vertical illuminance outdoors of about 20 lux appears justifiable
at present. Much less may often prove adequate (eg Lighting.com 2002). In general,
currently dimmer areas should not be made brighter. Systematic studies of places with
existing lighting controls, together with new field studies, are required to see if lighting and
waste light reduction does actually reduce crime consistently in due course, and whether this
can be done while reducing glare to maintain a sense of security. If there is sufficient case for
continued use of particular floodlighting installations, eg at amusement and theme parks or for
sports lighting, minimal light flux is required and highly effective containment of all spill
light is essential. Upwardly aimed lighting of any sort should be deprecated regardless.
Outright banning of floodlighting for commercial purposes is already justifiable, and would
‘level the playing field’ in terms of competitive advantage.
Looking for the Milky Way from downtown with shielded eyes on a clear, moonless night is a
simple and effective test for town and city lighting quality. Invisibility means that more effort
is required to reduce overall lighting and to stop waste light going directly into the sky.
Pending specification of photometric limits and adequately sensitive light meters, this is
probably the best available test, although the appearance of clouds as dark against the
moonless night sky may prove to be a useful alternative indication of good lighting. Overall
light levels and waste can be reduced together by early decommissioning of all upwardly
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