Plainfield Touts Buyback, Gun Shot Detector

Plainfield, New Jersey is yet another community to install gunshot detectors. I don’t honestly have much of a problem with this technology, as if I have to fire a gun within a city’s limits, I want the police showing up quickly. But does it actually work? I’ve yet to hear these systems revolutionizing police work, and their deployment, as best I can tell, has been pretty limited. New Jersey law enforcement seems to be keen on them, however. My guess is the system probably provides a lot of false positives, and doesn’t buy you much in terms of crime prevention for the cost. Cities would probably do better to spend the money on more police.

UPDATE: Interesting study:

Police response times to technology-generated reports of gunfire were compared to response times to citizen-generated reports both before and during the test period. For the most part, there was little difference between response times to technology-generated reports of gunfire during the test period and response times to citizen-generated reports before the test period. However, the mean response time to citizen-generated reports of gunfire during the test period (about 30 minutes) was about 30 percent less than the mean response time to technology-generated reports (about 45 minutes). Nonetheless, the overall mean response time during the test period (to the technology- and citizen-generated reports combined) was about 41 minutes, just 2 minutes longer than the mean response time before the test period (to citizen-generated reports only). Researchers concluded that using the technology did not change in any substantial way the speed with which the police responded to reports of gunfire.


There are two possible explanations for this significant increase in police workloads: First, gunshot detection technology may generate some false alerts. Given the design of the evaluation and the relatively early stage of this technology’s development, this first possible explanation could not be explored in more detail. Second, Dallas may have a high rate of unreported gunfire, at least in the Oak Cliff neighborhood; if so, this finding could have significant ramifications for future crime analysis and crime prevention activities that seek to control the random gunfire problem in Dallas.

Given that, it seems to me this technology is a net negative, if it’s not resulting in a better response and is consuming police resources. Yet the conclusion is still relatively positive. But then again, our society likes easy solutions to complex problems, so I guess it’s not surprising.

16 thoughts on “Plainfield Touts Buyback, Gun Shot Detector”

  1. Does the technology cost measure up to a significant percentage of putting one more cop on the street?

    If so, screw the tech, hire another patrolman.

  2. Markie Marxist sez: “Who cares if it works! It spends more tax dollars, and we have a 100% tax rate to get to, if we’re going to successfully communize America! Every city in America should have one, whether it works or not, whether they need it or not. We can put that in the next stimulus package. We’ll say that it’s for ‘crime control’ – people will like the sound of ‘crime control’ because it sounds impressive. I mean, they bought Obama because he sounded impressive, didn’t they? And he sold everybody a bill of goods. Even us Marxists.”

  3. Here in Cali my impression was that these systems were primarily installed in neighborhoods where it’s likely the police *wouldn’t* be called after a shooting. East Palo Alto comes to mind as an early installation for that purpose. The response-time difference is infinite in that scenario.

  4. Thinking about it, if there is shooting, and no actual person calls in, what exactly are the police going to do when they get there?

    There’s no complainant to provide any info at all. Heck, the people on the street when the cops roll up could be the shooters, the detector does nothing to identify them. Are they going to pat down everyone within an arbitrary distance of the detector? Spend an hour in a one block radius looking for a micro-stamped brass needle in a haystack?

    So why would the police prioritize a response?

    To drive by where someone might have fired a gun a half an hour ago on the off-chance there’s an unreported body laying right out in the open where they might actually see it without a thorough search?

  5. @Matthew Carberry:

    you look for bodies, casings, bullet holes, blood spatters, you check security cameras, you check hospital emergency rooms, you talk to people who might give you info but wouldn’t have called, etc etc.

    I work in law enforcement and we use shotspotter every day. Nothing’s perfect and there’s always human error (gunshot or firework?), but it is definitely very useful.

  6. I work in law enforcement and we use shotspotter every day. Nothing’s perfect and there’s always human error (gunshot or firework?), but it is definitely very useful.

    That’s a useful data point. As I said, I think the idea is fine.. and I’m not against the technology, but I’m wondering how well it really works.

  7. I know Paterson, NJ has had such a system for a few years now. Reading reports in the local papers has shown that on at least one occasion it resulted in an arrest when a gangsta wannabe showed off his new toy and fired off a few shots to impress his friends. On that occasion, he remained in the location of the shots and was still standing around when the police arrived.

    Although, I ‘ve often wondered if cartridges loaded with black powder (which have a distinctively different sound signature) could fool such a system.

  8. Prince George’s County, Maryland uses the gun shot detectors extensively around their border with Washington DC.

    I’ve heard good things and bad things. Like: the cops use the system, to be sure that the shots have stopped before they arrive. Like: lives are getting saved because the police and ambulances arrive while people are still dying. Like: cops are swooping in on gang-bangers trying to target practice.

  9. When I worked at the County of Berks, we reviewed shot spotter for use in the City of Reading. It certainly does work, but the cost and maintenance fees keep the system running makes it a questionable use of precious LE dollars. We did not buy the system.

  10. That the response time is 30 – 45 minutes to a report of shots fired, tells me all I need to know.

  11. From the newer article that jujube linked, about testing the system with hundreds of rounds and only one phone call coming in during that test:

    “They reckon that citizens are either distrustful of the police, fearful of retaliation, or simply inured to the frank pop pop pop of gunfire.”

    Or, they’ve figured out that calling doesn’t do any damn good.

  12. How closely does a car or lawnmower backfire sound resemble a gunshot? I think I need to go research this in a location that has a shot detection system. Do different size engine backfires sound like different calibers? Data collection is needed.

  13. @NevynPA:

    Car backfires occasionally come in as “possible gunshots.” Really it’s up to the people involved. People listen to the sounds that come in and code the (hopefully) appropriately, and the system learns from that coding what is and what isn’t a gunshot. With better people, and with people going through old data and correcting it, the system will be more accurate.

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