The history of gunshot detection in Chicago begins with a trial in 2004 by Safety Dynamics and a later pilot program in 2007 with ShotSpotter. In April, I noted that despite ShotSpotter – Not a Silver Bullet, the city felt gunshot detection was too expensive. The NBC reporters decided to pursue this story:

But now? Both systems appear to have gone by the wayside. A police spokesman wrote in an e-mail that the programs were “not entirely effective” in an urban environment. The cost of the programs were also cited. Despite repeated requests to interview Chicago police, our requests went unanswered.

Perhaps the reason for the silence is the fact that the city apparently hasn’t paid its bills. Officials from both ShotSpotter and Safety Dynamics said the city owes them money. Safety Dynamics said it would like its equipment back or be paid. Shot Spotter said the city owes them close to $200,000.

The story does mention (as will ShotSpotter) that there are cities that are happy with the results of the gunshot detection technology. The more interesting part of the story for me is not Chicago’s unwillingness to use the technology, but their inability to be open to the public about the technologies they use.

[From Ald. Leslie Hairston Wants To Revive Gunshot-Location Technology In Chicago - cbs2chicago.com ]

Fifth Ward Ald. Leslie Hairston wants Chicago to reintroduce the Shotspotter gunshot location technology. After all, Shotspotter’s web site says it can reduce crime. So why isn’t the CPD using it? Don’t they care?

The CPD did adopt Shotspotter and found mixed results in Chicago. Specifically:

The city conducted three separate tests of gunshot sensors between 2003 and 2007 in the West Side’s Harrison Police District. Only on one occasion did the detection system send a warning prior to a person calling 911 to report the shooting. As a result, the city felt the gunshot detection systems were too expensive at a cost of $200,000 a square mile.

The city is going forward with installing the technology in the Loop. However, Shotspotter is an expensive technology and the CPD decided it wasn’t the best use of their scare resources. The city of Chicago is approximately 227 square miles, so to cover the entire city would cost close to $50 million.

The Shotspotter technology locates gunshots. In a dense city, 911 calls often serve the same function. Gunshot location is a useful piece of information for police officers, but it is not a silver bullet. It cannot by itself reduce crime. If the system is reliable and works well with officers, it could lead to less shootings (but not necessarily less crime). The independent studies I have seen show the results are quite mixed.

In Chicago, there has been a rash of shootings in Chicago were no regard for the police or cameras. Shotspotter is now the silver bullet. I am concerned that Shotspotter is seen as the answer because people are scared. It doesn’t make sense to spend money on technology that makes us feel better, but is ineffective. The city can address this by making public its tests of Shotspotter. I would like more details about the tests, for example: How many gunshots were there during the tests? How accurate was the system?

This mixed success concurs with a similar study on the effectiveness of SECURES gunshot detection system (not ShotSpotter) released in 2008 (based on data from 2005-6).

Despite the lackluster results, the city is going forward with installing the technology in the Loop. It will cover all two square miles. The technology will allow for real time updates on shooters, while distributing this information remotely. The cost is expected to be around $400,000.

An article on ShotSpotter mentioned an independent study on gunshot detection.

In 2008, Peter Scharf, a criminologist at Tulane University in New Orleans, conducted a study for the National Institute of Justice about an early competitor of ShotSpotter, called Secures, in two Virginia cities. He found the system frequently sent the police on wild goose chases by reporting false positives, had an inconclusive effect on response time and, crucially, had little impact on arrest rates.

The report is very well done. Some of the interesting findings include how the gunshot detection system was negatively affected by radio frequency interference and fireworks/bottle rockets.

The report also discusses the tradeoffs between false positive and false negative error (an unavoidable part of these systems). The report found that “2/3 of SECURES®-related dispatches were “but-for false alarms” – both not a confirmed gunshot and no call corresponding call for service.

A 3-2 vote in San Francisco is cutting $360,000 that Mayor Newsom sought for installations and repairs of the anti-crime devices, i.e., cameras and gunshot sensors. The cut was motivated by the lack of evidence that the cameras and sensors were effective. This decision could still be reversed and it doesn’t affect all the camera/gunshot systems in the city.

The anecdotal evidence seems to show that gunshot systems are useful. Its unfortunate that there isn’t hard data to support the use of gunshot systems. I am afraid that these useful systems will be muddied by the less effective surveillance cameras.

Newark has chosen Shotspotter for a gunshot detection system over competing systems from Safety Dynamics (SENTRI) and Planning Systems (SECURES).

Gunshot detectors will be mounted on structures over a 7-square-mile area. When triggered, Shotspotter sensors will provide police with the location, number of shooters, and number of shots fired. . . . Shotspotter’s Gunshot Location System has also been installed in 27 cities around the country, including Washington, D.C., and East Orange. Newark’s neighboring municipality first introduced gunshot detectors made by Planning Systems Inc. in 2005, and deployed a Shotspotter system in 2006, according to Detective Andrew DiElmo of the East Orange Police Department. Both systems are in operation in East Orange.

Gunshot detectors are viewed as a “useful tool” for investigative purposes, and the East Orange police also considers it a crime deterrent, DiElmo said. However, there have been issues about gunshots that go undetected by sensors. “Does it work 100 percent of the time? No,” said DiElmo. “We have had incidents where the sensors haven’t alerted us.”

It also highlights some “success stories”:

Less headline-grabbing are the cases seen in Minneapolis since installing ShotSpotter last month. Police have netted three felons, two semiautomatic guns, and recovered one stolen car. It also provided additional information in three shooting cases. “It’s just a better compass. It still takes good cops, persistent investigation, and good police skills,” says Lt. Gregory Reinhardt, spokesman for the Minneapolis police department. “It’s just pointing us in a better direction.”

However, Lt. Reinhardt admits that none of the arrested felons and confiscated items were necessarily involved in the original shooting. In one case, police arrived to find a car speeding off. Police pursued, then apprehended a suspect – a convicted felon – who tried to flee. In the car was a loaded semiautomatic pistol. In two other cases, police arrived to find people loitering. On each occasion they took names and found a person wanted on a warrant. “It’s sort of hard to fathom that the purpose of the thing is to put police in a place where they can pick up people who are wanted on other warrants,” says Mr. Yohnka.

A final interesting point concerns data security:

Data security will be one of the first questions. The entire system uses encryption, from sensor to server to dispatcher, says James Beldock, president of ShotSpotter. The server stores a record of each gunshot report that includes the time, the sensor readings, and calibration data.

A few notes:

1. You get an immediate response by police with ShotSpotter, unlike with video cameras that are often not constantly monitored by police.

2. It appears police officers trust and believe in the technology. As a result, they are responding to gunshots more often. This shows how technology can mobilize manpower.

3. Cost – the rollout of 48 cameras costs hundreds of thousands and it would cost millions to wire the entire city.

4. It doesn’t say if there are any other possible uses of the gunshot detection systems.

The city bought 40 surveillance cameras in 2003 as part of a pilot program in six neighborhoods that never really took off. The cameras were never useful, in part because they ran over the public Internet and were very slow, often producing “video” that was so slow that it looked more like single-frame still shots. Those cameras are no longer used.

They also have a nice pdf of how gunshot detection works. And according to Jose Cordero, director of police in East Orange, the gunshot technology helps reduce gun crime:

Jose Cordero . . . said his department bought a system in 2005 and heavily publicized the new technology in the media, particularly the neighborhoods where cameras were installed. The result is that gun crime in those areas is down 85 percent, he said.

“Pilot stage is really a technical term,” said Bryan Baker, chief executive officer of Safety Dynamics, which produces the gun recognition technology. “When they define something as a pilot, that means there’s still a certain confidentiality about information. Once it gets reclassified as production and not pilot, then all the information becomes nonconfidential.”

So maybe once its out of pilot state, the rest of us will get more data on how well these systems are operating. The article also suggests what the next step maybe in these systems:

Several companies are creating a video analysis component that would recognize a shooting scene — the position someone would be in when holding a gun, someone lying on the ground or a group of people running. “They can digitize what somebody holding a gun would look like,” Baker said. “Then they can lock in and follow him. When you put all these things together, it can be successful in protecting parameters. You make it increasingly difficult for an intruder to escape notice.”