Schneier on Security
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September 12, 2007
Light and Crime
A New Yorker article on light pollution has a paragraph on light and crime:
Much so-called security lighting is designed with little thought for how eyes -- or criminals -- operate. Marcus Felson, a professor at the School of Criminal Justice at Rutgers University, has concluded that lighting is effective in preventing crime mainly if it enables people to notice criminal activity as it's taking place, and if it doesn't help criminals to see what they're doing. Bright, unshielded floodlights -- one of the most common types of outdoor security lighting in the country -- often fail on both counts, as do all-night lights installed on isolated structures or on parts of buildings that can't be observed by passersby (such as back doors). A burglar who is forced to use a flashlight, or whose movement triggers a security light controlled by an infrared motion sensor, is much more likely to be spotted than one whose presence is masked by the blinding glare of a poorly placed metal halide "wall pack." In the early seventies, the public-school system in San Antonio, Texas, began leaving many of its school buildings, parking lots, and other property dark at night and found that the no-lights policy not only reduced energy costs but also dramatically cut vandalism.
Posted on September 12, 2007 at 6:23 AM
• 66 Comments
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Let there be....
No more bright light.
Reducing such stupidly bright lighting would also save electricity (and therefore money). Some of that money could instead be spent on improving security in other, more useful ways.
The amateur astronomy community has been saying this for 40 years; most "security" lighting actually makes it EASIER for prowlers to do their work; because they glare so much it makes it difficult to see.
I've seen lights near the road that probably contribute to accidents; they glare right in the face of drivers.
http://www.space.com/spacewatch/... - between $1 and $2 billion annually is wasted on inefficient / ineffective lighting in the US alone.
A good general rule is, if you can stand outside the area that's intended to be lit and see the bulb, it's a bad fixture. And, the area to be lit should NEVER include anything off your property. If you're casting light onto my property, that's called "light trespass."
I recently went to a home improvement store and found an entire aisle full of really horrible, ugly lighting fixtures (but boy, were they cheap!). I didn't find ONE outdoor fixture that met IDA standards for "good" lighting.
I wish people would use the same aesthetics when putting in outside lighting as inside. Most of the outdoor lighting is the equivalent of hanging a bare 100 watt light bulb over a formal dinner table.
When I was a kid walking after dark I avoided lighting. Even a little kid can figure out that if you're lit up you can be seen by all the people around you that are hidden by the dark, and you can't see any of them. I tried explaining this to grownups, but they refused to see it.
Rage! Rage against the wasting of the light.
Though perhaps it isn't always the best security solution the use of flood lighting is at least an understandable one. Regular workers and security guards will feel not very comfortable when their only light is what they have in their hands. The shadows around them will be simply frightening and perhaps rightly so. In many cases lights that have to be switched on will be mistrusted, so the cheapest solution may well be just to leave them on.
Increasing the lighting in Chicago's alleys (replacing the lamps from 90 to 250W) increased crime by 21% compared to a control area.
For Derob: When does lighting become excessive and expensive and unhelpful? What if it makes shadows darker, and people's eyes close down due to glare, instead of allowing people to see? When will people get over their irrational childhood fear of the dark? Billions of dollars, literally, are spent in energy costs for the light that never hits the ground and only goes up. I'd be happy for well-designed lighting for workers; but for security guards? It makes their jobs easier if the criminals need a light to get around. And you'd be shocked at the price of lighting: often well above the cost of having a full-time guard driving around. And with the lights, you'd can't afford the guard. Which would a company rather have? Lights, with no one to see the crime in progress, or a guard who can see the crime because the criminal's got a flashlight?
@Dean, "Increasing the lighting in Chicago's alleys (replacing the lamps from 90 to 250W) increased crime by 21% compared to a control area."
Criminals are afraid of the dark? !
You want to really mess up criminals? Put lights on a 10 second flash. 10 on, 10 off. 10 on, 10 off. First it's annoying, but more importantly, it will keep them pretty blind - their eyes won't be able to adjust to the light or the dark.
Is the 10 second interval sufficient to defeat a criminal alternating which eye is open? And how does the power usage stack up for constant-on vs. on-off?
@Dean, "Increasing the lighting in Chicago's alleys (replacing the lamps from 90 to 250W) increased crime by 21% compared to a control area."
Probably made sparsely-populated and hard-to-see alleys more likely to be used by vulnerable pedestrians.
The article has a glaringly (cough) stupid assumption: it assumes prowlers in dark places will use flashlights. Wrong.
Given a choice between two corridors (say, in a meandering condo complex) the prowler will choose the darker one. Or if the whole place is well lit, they will probably just stay away period.
Lighting should be placed down at ground level to avoid glare and to minimize scatter (to protect astronomy). For security, lights should have sensors and should go on when motion is detected. Most sensor lights have sensitivity settings; if possible these should be set appropriately to catch actual humans walking past, but not smaller movements such as birds and squirrels.
Perhaps lighting doesn't have anything to do with facility security?
I expect most lighting has more to do with discouraging litigation than with discouraging criminals. If someone is mugged on your unlighted property, you may face legal liability; if you install lights, you can demonstrate that you did something--even if what you did was ineffectual, at least it was what was expected.
You could site the dark is safer studies if you are sued. otherwise you are over-reacting to FUD.
I once worked for a farmer who followed this rule. His barnyards, equipment, everything was pitch dark. He said "If anyone is going to try to steal my stuff, I want to make it hard for them."
And that farmer's name was Glo Laternhead. He moonlighted as a lighthouse watchman.
Off topic: NYT on complexity in large computer networks:
The closing quote brings up the economic problem:
“We throw this together, shrink wrap it and throw it out there,��? he said. “There’s no incentive to do it right, and that’s pitiful.��?
@ Guvn'r: "Criminals are afraid of the dark? !"
That's the premise Batman is working from, anyway.
Savvy criminals don't use flashlights -- they use night vision google that can be purchased at any surplus store or from the internet.. and if they are really smart, they toss an object or small animal into the area to see if it trips a motion sensor...
I say lets increase them to 10e6 watts and get rid of the problem.
They will try to increase crime by your formula and we can fry them all in one shot
Then to keep Bruce happy, we will turn off all the lights till we find out from another Rutgers study that turning lights on reduces crime.
Some of these professors are idiots and I have found that increasing their salaries by 10% makes 21% of the idiots attempt to become college professors.
It would seem there are two differing scenarios here. If trying to protect property, less light is better. If trying to protect people, more light is better.
@Anonymous - "Savvy criminals don't use flashlights -- they use night vision google that can be purchased at any surplus store or from the internet.. and if they are really smart, they toss an object or small animal into the area to see if it trips a motion sensor... "
Savvy criminals are
(a) pretty much fictitious,
(b) to the extent they exist, not the ones snatching purses, stealing car stereos, or burgling working-class houses for a few hundred dollars worth of consumer electronics, and
(c) in any case, not much of a danger to thee and me.
I don't care about criminals clever enough to organize night-vision goggles. Heck, I barely care about criminals with the sense of planning to go buy a $3 flashlight.
The ones I worry about, because they're the ones who might be an actual danger to me and my family, are the ones who need money _right now_ to buy nasty drugs, and can't think of any better plan than rolling people for their wallets by the ATM.
And these are the criminals whose actions are opportunistic, and so who can be deterred by simple opportunity-reducing measures such as not screwing up the lighting.
@Curious - "If trying to protect property, less light is better. If trying to protect people, more light is better."
Not always, by any means. Putting lots of light by an ATM means that criminals can lurk half a block away in the shadows, and see who's taking out money. The victims are coming out of a well-lit (i.e. glare-y) area, and so can't see who's coming at them from out of the alley. And it has the perverse effect of making customers feel safer, so they're more, not less, likely to use the machine at night.
Putting poorly thought-out street lights all over the place that don't direct their light properly means that people walking around are blinded by glare, and it produces handy shadows for lurkers to hide in.
Maybe they are just afraid of the Shadow.
did you notice that these thingys are a great target for your air gun?
Darker is safer? And no one made the obligatory Security Through Obscurity observation yet.
Now playing at the Security Theatre: Lights, CCTV, Action!
@Darker is safer? And no one made the obligatory Security Through Obscurity observation yet.
Posted by: Brian S
I hope you are being sarcastic. Security through obscurity does work and provide some benefit. And is used effectively ALL of the time.
May cause a potential attacker to totally overlook the target.
Forces an attacker to potentially make more noise.
May slow the attacker down.
May force an attacker to spend more resources on the attack than can be gained by succeeding.
HOWEVER -- if it is your only layer of security; well that is not wise.
Not unlike a police presence in a high crime area. Although that might seem "oxymoronic", the security lights [floods with a motion sensor] work perfectly.
You are dealing with probability here...by that I mean, what are the odds are a would-be-thief will stick around if a motion flood kicks on ? Better yet what if you have a common area and you are aware [perceptively speaking] that the light has been activated ?
Also energy efficiency is another concern here as you need to light common areas ...this is code in many a counties. But if it is timer driven, and then circuit controlled by a motion sensor you have a few benefits.
...I could go on an on but IMO, myopic posts about the supposed inverted logic about lighting [security] to ultimately generate web traffic is a waste of time.
Have a nice day...
I'm surprised to see that this group has such a narrow definition of security.
The biggest lighting-related risk to a typical business is NOT a burglar or tagger. A much, much bigger issue is the safety of the business' own employees, who need ground-level lights so that they don't trip and fall over every little rock, pinecone, or piece of trash in the parking lot.
(Yeah, yeah: it's summer now. But in three months, sunset will happen at 4:30 p.m., and it'll be dark by the time I leave my office at 8:00 p.m. Even if I had good intentions about paying attention, I'm going to be tired, hungry, and distracted by a thousand things.)
Think about this as a "data integrity" issue. If your database is hopelessly corrupted -- or your star employee laid up with knee surgery or a broken wrist, or the laptop s/he was carrying is dead -- then it doesn't matter how hard it is for the hacker to get inside.
Your business was already screwed when you decided to ignore your internal risks in favor of the sexy external ones.
The auto burglary cops in SF said in an SF Chronicle article that lights help criminals decide what cars to break into and that lights increased break ins because they could see the contents of the car better.
Good, well designed lighting is essential to security. Notice my conditions.
The light pollution people managed to make UC San Diego a haven for campus crime. The parking lots were actively dangerous at night when I was there.
There are trade-offs, particularly as security lights allow bad guys to spot patrols. Security lighting does a good job of deterring casual criminals WHEN there are observers likely to call police. Inside a large private perimeter (school, industrial yard, etc) and in a bad neighborhood, you don't get many 911 calls.
Burglary isn't the problem it once was. Things that were once stolen are now so cheap to buy new no one wants knock off goods.
Cash and credit cards are more interesting now and more easily obtainable on the streets via a bag snatch or pickpocketing.
I've noticed for a long time that the safe neighborhoods (where one can leave a kid's bike on a front lawn for *days*) are a lot darker than the unsafe neighborhoods (where said bike cannot even be locked on a porch, but must be kept inside a locked building).
Lighting is one of those things that insurance companies and law enforcement like, so it gets installed. A person can point to it and say, "I did something." Never mind that it didn't work...
Hi, I guess lighting up your property is probably more for the owners sense of security. Most people have a little sense of being afraid of the dark, and why not seeing is one or our greatest sympathetic senses. A person has to know when to (in my case flight) fight or flight. Very cool I am going to link to your site. My site is on scam busting, so it goes well.
I recall having to break into my *own* apartment on one occasion and being grateful when the motion-activated backyard floodlight came on - made the job much easier! Seems obvious to me that the lights are only a deterrent if somebody else is around to see what you're doing.
Crimes dropped when street lights were put out in two cities in the north of Sweden. Traffic was also calmer and no rise in traffic accidents.
Övertorneå and parts of Haparanda was darkened for at least five months last winter, because of a dispute over energy prices. Article (in Swedish):
Translation of some passages:
"The number of thefts and burglary has been halfed since the city was darkened this autumn  because of the well-known dispute with Ekfors Kraft [local energy company]."
"- We thought it would be the opposite, says Sören Mukkavaara, police constaple in Övertorneå."
"To prevent [traffic] accidents, the school children in Övertorneå got reflector vests and in Haparanda they have been equipped with flash lights."
"- There has been no accidents that can be deduced from the darkness, says Sören Mukkavaara."
Dean W. Armstrong: can you provide a citation for your claim that brighter lights in Chicago alleys encourages crime? I've been arguing with my alderman over this: the streetlights around my house are bright enough to allow me to read by while I'm in my house, even on the second floor.
Oh, lighting increases crime...got it...So that's why everythings so groovy when a city has a brown out.
One aspect of security lighting installations that often gets overlooked, is WHO is going to be using this light to see a crime in progress and report it.
If you're a big business, it might be your own guards -- but most of us can't afford 24 hr on site guards.
If you're on main street, it might be a casual passer-by who decides to do his civic duty. But anywhere off main street, this is pretty unlikely. Far too unlikely to rely on.
No, the person most likely to see the burglars and report them is your neighbour. This leads to two important conclusions:
a) by installing security lighting, you are effectively asking a favour of your neighbours. Some basic reciprocal courtesies are therefore recommended. In fact, it's probably a good idea to go talk to them about it. The worst thing you can do is to install "security lighting" that annoys your neighbours, the very people who you are asking to use it!
b) the important criterion for effectiveness of the lighting is visibility from the neighbours' premises, at night. Looking at it by day is so obviously a waste of time most better installers will know to check it at night, but they do so from the customer's premises. This is useless, the only people there during a burglary will be the crooks. If you go over to your neighbours' premises and find that from their point of view your "security lighting" creates dazzling glare, then you've just spent a few thousand bucks making life easier for the criminals.
On a visit to the Lowell Observatory (http://www.lowell.edu/) in Flagstaff (which I don't think of as a particularly badly overlit town) the observatory staff spent a significant portion of their public outreach effort arguing for less light pollution. It's bad for astronomy, but it is also bad for all the reasons discussed above.
Selfish, myopic astronomers are part of the problem here:
Flagstaff is one of a few cities that switched to low-pressure sodium lighting, which illuminates poorly and makes it impossible to distinguish colors. Some of the problems include telling blood from oil, knowing the color of a fleeing vehicle, and being able to see obstructions in the roadway before you hit them.
High pressure sodium lamps, when used in moderation and installed in a way that minimizes glare, are very much preferable.
(Of course, the surveys claim otherwise, because most of the individuals who care enough to vote on this sort of issue are moonbat activists.)
San Diego installed LPS back in the 80s. The city is picturesque during the day, but dark and creepy at night due to these ugly orange lights.
without detection, flashing lights (say from a motionsensor activated flood) as a sign for crime in progress is useless. so why bother, if no watcher is around?
continual lighting has the only effect of makinh it easier for criminals to do what they want... if they wear a guise of a security person i bet they will even be assisted, if someone notice them.
I live on a heavily used bike path in Boulder. I knew about this factor and my deck lighting is near ground level, shielded and triggered by motion. Anyone moving around can be easily observed.
Other people, on the other hand....
The worst cases are a few hundred meters down the path. Both have extremely bright lights. In one case they're across a wooded creek and it's literally painful to glance in that direction. In the other case it's on the same side of the path and shield by a berm, but the trees overhead are lit so brightly that they function as bright overhead lights.
My biggest concern isn't intruders at either house, it's that it's impossible to see anyone lurking in the shadows nearby since your eyes have had to adjust to the bright light. You won't have attacks during 'regular' hours, but traffic does drop down in the late evening and targeted pedestrians would be easily identified. Meanwhile nobody would think twice about the guy standing on the path, if he made any effort at all to look like the average user. (In Boulder, that's either look like a college student or somebody exercising. :-)
There is no reliable scientific evidence that outdoor lighting deters crime more than it facilitates crime. There is good evidence that darkness reduces crime. See parts 1 and 2 of my report on 'Outdoor lighting and crime' in the light pollution section at http://www.asv.org.au or at
http://amper.ped.muni.cz/bajc in the crime directory with papers by Dr Marchant also.
So Dr. Clark it seems that the logical conclusion of your research is that once we all exist in an astronomer's perfect world of total night darkness, we will have shifted crime to that only occuring in daylight.
The problem witrh sites such as this allow for comments
You've got to be kidding. This nonsense about lighting not deterring crime is simply a hoax perpetuated by astronomers and light pollution fanatics who have a particular agenda. Lights deter crime. The key issue is the type of light used, how it is placed and where it is placed. Yes poorly placed/designed lighting can be problematic from a number of perspectives. Properly installed lights at the right location does deter crime. Stop listening to the fanatics and the lunatics from Berkeley California.
I tend to agree with you here, whatajoke. Lights can and do deter crime, especially violent crime. If an area's well lit, a perspective burglar, molester, etc, is more likely to be frightened off because they stand a better chance of being noticed. Also, that's why the common advice for being out late at night is to stay on the well-lit main streets, and not to go up a dark side street, alleyway or hallway, because a criminal will be only too happy to follow you.
the best lites are the one that give u both.it cimes in at dusk dimmely,then gets bright if some one comes into range. u get some lite to see out and servey the area,then brighten up . u get to set the range,problem is finding them
"Dark favors the defender." Ask any Marine combat commander.
I am the defender, the burglar is the aggressor. I have kept my house dark since I bought it, and have had not so much as an attempted break-in.
I will not light the way for people trying to steal from me. Or worse.
reading these comments it is obvious that most of the writers know nothing about lighting. and the comments about Chicago alleys cracks me up hey who is it in the alley after hours? they are the persons that like hidden spots whether lit or not. now they end up killing, robbing assulting and raping each other. they live and reap the consequence of their surroundings. that's the reason for their climbing rates. it keeps them out of my neighborhood.
the thought of 10 second cycles is a huge waist of $$$$. the inrush on HID lighting is more than constant and the life of the lamp and ballast is significantly reduced (energy waste to the max$$$).
they all seem to think and talk about glare, yes this can be aproblem if you look into the bulb. the notion that ground level lighting is better is wrong short poles add to the number of fixtures needed more $$$ & energy glare is a factor of angle of light therefore taller poles reduce glare and numbers of fixtures. i do agree that i have seen many areas lit to 50 fc and above when 20 fc will do. one thing that most of your writers miss is that many of these security systems include cameras and to have cameras you have to have light.
if you really think security lighting is a waste then send your wife and kids into the darkness to shop and play. or ask a rape victim what they think.
"if you really think security lighting is a waste then send your wife and kids into the darkness to shop and play. or ask a rape victim what they think."
Lighting both works and does not work as a crime deterant, and sometimes it actually works for the criminal.
To pretend otherwise is a little silly for the following reasons,
For instance a bright light illuminating the front or side of a building will make a person who looks suspicious more obvious if they are seen, so this would apear to be a benifit.
However the criteria for it to be a success is, if and only if somebody is actualy watching and responds in a timely fashion, which is very doubtfull these days in most places.
Also a criminal may decide to attack a well lit building, knowing that the lighting will actually be of benift to them, in that it alows them to see what they are doing, whilst not attracting attention in the way that a torch or flashlight would, so that is a minus point.
Then there is the argument that a well lit target will discorage a criminal and make them go someplace where there is less light.
Well so many places are well lit these days a criminal does not realy have much of a choice on that score.
Also in some places there is sufficient lighting so that likley victims do not have to go into dark areas. So due to the amount of security lighting in some places it now has little or no effect as the only targets/victims available are in the light.
However at the same time one area of high intensity security lighting in an otherwise low lit or unlit area makes other areas around it effectivly in deep shadow. So this again actually makes a suspicious person a whole lot less visable than if the lights where not there.
There are a whole load more aspects to be considered each have different numbers for any given location and the numbers change depending on the changing suroundings and environment, so need to be continuously assessd.
Then there are the criminals themselves, broadly they fall into four areas,
The further up the scale the less likley they are to be either woried or detered by security lighting.
However whilst passive security lighting is not likley to be much of a deterant to any of the criminals active security lighting which causes a very sudden change in intensity when a suspicious person moves into a controled area is probably a great deal more effective against the first two types of criminals as it activly attracts attention.
Like CCTV security lighting is only realy effective against the majority of criminals where it is backed up by an obviously and attentive human backup that investigates any and all persons entering a controled zone without fear or favour.
However not even this will deter proffesional criminals. They will expend the time and energy to circumvent it.
The important thing to remember is that all individual items of security physical or otherwise deployed is,
1, Only a delaying device.
2, Can always be circumvented.
3, Only of use if backed up by an active and obvious human prescence that responds in a timley fashion.
4, Only one part of a whole system.
Therfore to argue the merits of one item of security without knowledge of the context of which is being used is of little benifit and therfore silly.
"Regular workers and security guards will feel not very comfortable when their only light is what they have in their hands."
Speaking as a security guard who works mostly at night, the first thing I do when everyone else leaves is turn out every light that I have control over. "Darkness favors the defender," and my site is one that would be extremely hard for an intruder to navigate stealthily in the dark. I can walk well-known paths with very little light and avoid hazards, while anyone with less familiarity with this site would be tripping over equipment and knocking things over. If an intruder has to bring a flashlight, it provides a nice beacon for me to find him by.
I had a nice big hefty high pressure sodium on my house, the neighbors liked it because it lit up the street. I pulled it because my plants were getting confused.
No kidding, you can tell new growth on a tree by it's bright green color, and my trees and bushes were getting lanky and weak new growth.
So, no lights, but now I'm disturbed by the sound of visitors bouncing off my front door, and me when I drop 20 pounds of detergent off my toe. So I'll get the best motion control sensor and lantern I can, the ones that come with the sensor in them are way too ugly.
Just saying. I really have no excessive fear of short-sighted crooks, but my house will be nicer if it greats people with a nice mellow light. And I hope to save money by using Motion Control devices.
" ...but my house will be nicer if it greats people with a nice mellow light. And I hope to save money by using Motion Control devices."
You might want to check power consumption carefully.
Most motion control devices draw power continuously, and they do not convert mains electricity to the Low Voltage DC very efficiently.
You might be better off using a modern high efficiency low energy light and a timer.
For instance you can get "clear water" LED lights in G10 format that draw only 2W or low presure flouresents in E27 fit that draw 4-8W.
Some electronic timers draw a lot less than 1W when off and only marginaly more when on.
A lot of cheeper motion detectors draw the equivalent of 15W all the time due to their power supplies.
Measuring the power "you pay for" at low levels such as these can be difficult because of "power factor" and the way your electricity meter measures power.
I would like to hear some of the alternative effects that light pollution has on crime rates, such as the fact that there is a proven correlation between young children's ability to see the stars throughout their childhood and the probability of them entering into a life of crime. When we can see the stars, we ponder our place in the universe, and our consciousness expands.
Most crime of the kind we fear occurs in daylight, ergo criminals need light. Lighting, especially street lighting, encourages people to behave at night more as they would during the day. Consequently our most crime infested areas are also the most intenively lit.
Well designed motion operated lighting, correctly installed may be a deterrent, but lights that are left on all the time are not. They make the intruder's task easier. Unfortuately they simply waste energy, decimate lower trophic levels in the food-web, and precipitate neighbour disputes.
Outdoor lighting should only be installed if construed to be useful, and applied sparingly on a needs must basis, where needed, when needed and in the right amounts. Furthermore it should only be applied using appropriate technology that has been specifically designed for the purpose.
I have three motion lights. So far, one potential burglary, and one public urination on my front yard were not deterred by them. It appears low lifes know that the public will not call the police no matter what they are doing. I'm thinking motion lights are overrated at this point. They are like car alarms. No one pays any attention to them. The potential burglary was only thwarted because my driveway alarm went off, and I called the police. The guy, dressed in all black, was booked for being under the influence.
I'm probably going to replace at least one of them with a dusk-to-dawn metal halide floodlight, to help my CCTV camera get a better image. The police can do more with a good image.
When I used to write graffiti I would take the dark streets / alleys any day over the lit ones, it seems so much easier to lurk up to a spot, turn around to look for observers in buildings / cars, and bomb up a wall, all under the cover of dark. For example, you can see everything going on in the street if the streetlamps are on, if youre in the alley and it's pitch black, so you have advance warning when a cop / early morning jogger etc. tries to come at you.
An old post but no less relevant.
Had several police officers looking around the neighborhood the other night for someone - ironically the place they were looking was at the lit end of the street. What does that say about lighting?
It seems to me, that in this study, perhaps the criminals just got away because THEY WERE NOT SEEN BY ANYONE!! What a farce!
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