Astronomical Society of Western Australia Inc
- comments on the City of Perth draft lighting strategy Conclusions
The City of Perth draft lighting strategy is deeply flawed and in our opinion should be rejected for
the following reasons:
1) The statements in the strategy about safety and security are deeply problematic and are
prime examples of what is warned about in the existing literature, namely that:
“Governments should ensure that resources are not wasted by the installation of any more
security lighting or other outdoor lighting at all where the justification includes or implies
crime prevention” (Clark). We urge that on the next iteration the WA Police be consulted and
the reviews by Clark be considered.
2) There is no consideration at all of the potentially serious health problems of bad or excessive
lighting. We urge that on the next iteration the issue of the effects of excessive lighting on
the health of the citizens of Perth be addressed.
3) There is no consideration at all of the problem of light pollution, indeed the strategy builds
on the idea of Perth as a City of Light, whereas more people come to Western Australia to
see our darkness than to see our lights. We urge that on the next iteration the issue of light
pollution be addressed.
4) The document shows an accepted example of good lighting in the City of Lyon. But all the
existing and planned images shown of Perth in the document are light years away from that
example. The document gives zero confidence that best practice will be followed. The input
of a skilled lighting artist is most urgently required.
Our eyes
It is the rod receptors in the eye which are used to see in low light levels, but they only see scenes in
black and white. It takes 4 seconds of real dark for our eyes to adapt to the dark physically. It takes
30 minutes for them to adapt chemically to maximum sensitivity, not coincidentally roughly the
time of twilight before the full darkness of the night. When fully dark adapted, the eye can detect
single photons (but not every photon as some will fall on areas where is no receptor). Any bright
light seen during this period means the eyes have to start adapting from the beginning, which is why
astronomers jealously guard their dark adapted eyes. The exception is red light since our eyes are
relatively insensitive to red light. Bright white light, and especially blue light, immediately destroys
our eye's dark adaption. Significant levels of blue light not unnaturally also signal to the brain that it
is day time now, which is why reading a backlit computer device such as an e-reader is not a good
idea before trying to go to sleep.
The eye can integrate scenes up to about 4 seconds, in the same way as a camera takes long
exposure photos. It can see a greater than 10,000 range in contrast detection, greater than any film
or consumer digital camera. This is why professional photographers use fill flash, diffusers, and
reflectors to try and compete with the greater dynamic range of the eye. An example of what this
means is seeing the Trapezium star cluster in the Orion Nebula. Photographs (film or digital) will
show the nebulosity, but then the four stars in the Trapezium are grossly overexposed, or if the stars
are correctly exposed, the nebulosity cannot be seen. Photographs of the nebula are normally
manipulated by combining images of different exposure lengths to bring out the details in both the
bright and dark areas. The eye can see both the stars and the nebulosity, but only up to 4 seconds
exposure.
What the eye's enormous dynamic range means for a lighting strategy is that different light levels
can achieve the same effect. When streets were first lit by gas lights in the 19 th century, people were
amazed at the brilliance of the lights, yet when the first electric lights appeared these gas lit streets
seemed dimly lit. And the same is true for each new generation of lighting technology, and will be
until our lights are as bright as the Sun.
Safety
It is claimed in the draft strategy that: “Improved lighting is closely tied to reductions in crime rates
and improved levels of public safety. Areas which are well lit and have opportunities for passive
surveillance (or “eyes on the street”) are far less likely to experience incidents of criminal or antisocial activity.”
The one reference given in support of this statement is: Painter KA & Farrington DP, The financial
benefits of improved street lighting based on crime reduction. Lighting Research & Technology
33.1 (2001).
In truth the situation is far more ambiguous. A report to the United States Congress (reference
below) summed up the state of research as: “We may speculate that lighting is effective in some
places, ineffective in others, and counter productive in still other circumstances. The problematic
relationship between lighting and crime increases when one considers that offenders need lighting
to detect potential targets and low-risk situations”.
“Preventing Crime: What Works, What Doesn't, What's promising”, A Report to the United States
Congress, Prepared for the National Institute of Justice, by Lawrence W. Sherman et al, 1997,
available at https://www.ncjrs.gov/works/wholedoc.htm
We are attracted to places with bright lights as they appear safe and welcoming compared to the
darker areas outside the pool of light. With no restrictions, there would be a race to be the brightest
to attract the most people. But this is all relative, without any competition from other sources, a
campfire will appear welcoming.
There is sometimes a perception that the brighter the lighting the safer the environment. This is
triggered by a natural fear of the dark, and then following the unthinking logic that therefore the
more light the better. But it is good lighting which results in a safe environment, not necessarily
more lighting. After all, thieves, rapists, and murderers are also human and have the same emotions
about light as other people. And they can use over lit areas to pick out their prey and scope out the
area in safety. If there are dark areas, say from the 1st floor level and above, potential criminals will
be less secure since they will not know if they are being observed.
If you stand under a street light with darkness all around, anyone in the dark can see you from
kilometers away, but you can only see for a few meters. In that situation you would be much safer
to move well away from the light into the dark, and not keep shining your torch to see what is out
there. This is why prey animals who move around at dark shun the light since it makes them a
target.
The Astronomical Society of Victoria has prepared documents reviewing the available research and
we urge that the documents: “Outdoor Lighting and Crime”, Parts 1 and 2, by B. A. J. Clark of the
Astronomical Society of Victoria, Inc., available at: http://asv.org.au/light-pollution.php. be studied
as part of the development of Perth's lighting strategy. Clark's review noted a positive correlation
between increased lighting levels and drug crime arrests at Melbourne metropolitan rail stations.
Indeed it suggested a hypothesis the opposite of what this draft strategy claims, namely that for
whatever reason there is a positive correlation between increased lighting levels and increased
criminal activity. We therefore urge that the WA Police should be consulted as part of the
development of the lighting strategy.
The Royal Astronomical Society of Canada has also investigated the effects of lighting on crime. It
is worth quoting directly from their web site (http://calgary.rasc.ca/lp/frame.html):
“A test in West Sussex, UK showed crime went up in lit areas. In certain test areas,
all-night lighting was installed; other areas were kept as control areas. West Sussex
Police monitored the crime patterns for comparison with the previous year in both
test and control areas and polled residents about their perceptions and the affects
of the all-night lighting.
Polling results confirmed people thought lighting prevents crime and most residents
felt safer after the all-night lights were installed. Crime statistics, though, showed a
55% increase in crime in the test areas as compared to the control areas and to the
county as a whole! West Sussex has subsequently decided against all-night lighting.
And there's another surprise: Police report that such darkness is often safer. That's
partly because neighbors soon learn to alert police if they see any lights on in a
building. There's even less graffiti because it's usually lighted walls that attract the
spray-can vandals, not dark ones.
The San Diego police have gone on record indicating they see no real influence of
lighting source on crime levels. Commonly, people's perception about what lowers the
risk of crime is not based the facts of the situation.
Vandalism and graffiti have been successfully reduced in many American schools with
the Dark Campus Policy that was begun in San Antonio in the 1970s. Vandalism and
graffiti-and the associated cost of repairs-dropped immediately when "security"
lights were removed or turned off.”
A strong conclusion from the review by B. A. J. Clark of the Astronomical Society of Victoria is:
“Governments should ensure that resources are not wasted by the installation of any more security
lighting or other outdoor lighting at all where the justification includes or implies crime
prevention”.
Aesthetics
This is subjective and a therefore a good reason why a lighting designer also needs to be an artist.
Since it is more difficult for a lighting designer to learn to be an artist than it is for an artist to learn
to be a lighting designer, the foremost emphasis should be on obtaining a good lighting artist.
However, if we may venture a subjective opinion, the example chosen in the draft lighting strategy
of the City of Lyon, shows a good example of the controlled use of lighting - contrast this with the
garish use of the lighting shown in images of Perth in the draft strategy, which in our subjective
opinion are examples of bad lighting.
Health
There are indications that excessive levels of light at night are harmful. We do need proper sleep
and too much light, especially white and blue light, can disrupt our sleep potentially causing serious
health problems. This issue has not been addressed in the draft strategy.
Light Pollution
One of the principal wonders of the natural world is the night sky. And to see a truly dark sky is one
reason why people visit Western Australia. Most people do not come to see our lights, they come to
see our darkness. Out in the wheat belt on a clear Moonless night, you can see the glory of the
Milky Way arching overhead from horizon to horizon, you can see our satellite galaxies the Large
and Small Magellanic clouds, and at the right time of year you can make out the Aboriginal
constellation the Emu in the Sky - made up of dark nebulae standing out against the background of
stars.
This view is compromised by light pollution spilling into the night sky, an issue not addressed in the
draft strategy. The dome of light cast by Perth has meant dark sky astronomers have had to retreat
away from Perth. But the description dark sky is really a misnomer. Once your eyes have adapted,
on a Moonless night with little light pollution you can walk around just by the light of the stars. It is
the light cast by the Milky Way that you use to avoid bumping into things. It is not a dark sky, it is
ablaze with stars.
Dr Andy Simmonds, president
on behalf of The Astronomical Society of Western Australia Inc.
24 June 2014
ASWA
PO Box 421
Subiaco
WA 6904