REPORT TO PUBLIC SAFETY COMMITTEE ON A GUN-SHOT LOCATION SYSTEM KNOWN AS "SHOTS POTTER"

8/14/2019 REPORT TO PUBLIC SAFETY COMMITTEE ON A GUN-SHOT LOCATION SYSTEM KNOWN AS "SHOTS POTTER"

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LOS . _...GELES POLICE COMMI~_ LON

JOHNW.MACKVICE PRESIDENT

R IC HA RD M . T EFAN KEXECUTIVE DIRECTOR

B OA RD O F

POLICE COMMISSIONERS

A NT HO NY PAC HE COPRESIDENT

ANDRE SIRODE, JRINSPECTOR GENERAL

AN DR EA SH ER ID AN O RD INR OB ERT M . S ALTZ MA N

ALAN J. SKOB N

A NTONIO R. VILLARAIGOSAMAYOR

EXECUTIVE OFFICESUITE 144150, PARKER CENTER

150 N. Los ANGELES STREETlOS ANGELES, CA 90012

( 21 3) 4 85 3 53 1 P HO NE

ISABEL ROSASC OM MI SS IO N E XE CU TN E A SS IS TA NT II

213 485-8861 FAX 213 485-9818 TTY

October 3, 2008 BPe #08-0428

The Honorable Public Safety CommitteeCity of Los Angelesc/o City Clerk's OfficeCity Hall, Room 395Los Angeles, CA 90012

Attention John White

RE: REPORT TO PUBLIC SAFETY COMMITTEE ON A GUN-SHOT LOCATION SYSTEMKNOWN AS SHOTSPOTTER

At the regular meeting of the Board of Police Commissioners held on Tuesday, September 30,2008, the Board APPROVED the Department's report relative to the above matter.

This matter is being forwarded to you for your approval.

Respectfully,

BOARD OF POLICE COMMISSIONERS

~ ~ ~ . ISABEL ROSASCommission Executive Assistant II

Attachment

c: Office of Chief of Police

OCT 9 2 8P UB UC S AF ET Y

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INTRADEPARTMENTAL CORRESPONDENCEBr~;ffo8-jif2g

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SE P 192 8eptember 26, 20081.8WJB #08-0032 POLICE COMMISSION

REVIEWED

The Honorable Board of Police Commissioners'.. C /l _

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FROM:

SUBJECT: REPORT TO PUBLIC SAFETY COMMITTEE ON A GUN-SHOT LOCATIONSYSTEM KNOWN AS SHOTS POTTER

RECOMMENDED ACTION

That the Board of Police Commissioners REVIEW and FORWARD the Department's report fortransmittal to the Public Safety Committee regarding a gunshot location system known as ShotS potter .

DISCUSSION

In response to a Public Safety Committee Motion, Detective Bureau has researched gunshotlocation system called ShotSpotter. Furthermore Detective Bureau has looked at other gunshotrecognition technology and its potential usefulness to police operations. A staff report has beencompleted and is attached. This report addresses the following:

Description on how ShotS potter works and its capabilities; Results from investigating gunshot recognition technology; Other vendors that are involved in gunshot recognition technology.

If you have any questions, please feel free to contact Deputy Chief Charlie Beck, Chief ofDetectives, at (213) 847-4491.

WILLIAM J. BK--:~Chief of Police

BOARD OFPOLICE OM MISSION IS

ApprovedSEP3 0 l008

Secr~~ ~t O hd~Attachments


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RESEARCH ON GUNFIRE LOCATION TECHNOLOGIESAND SHOTSPOTTER

A Staff ReportPrepared by

Tactical Technology Unit

August 22, 2008

PURPOSE

On July 29, 2008, the Los Angeles Public Safety Committee passed a motion requesting theDepartment to research a gun-shot location system known as ShotS potter and other similargunfire location technologies. Furthermore, the Public Safety Committee requests theDepartment to investigate its applicability and potential usefulness to police operations.

BACKGROUND

According to the vendor, the ShotSpotter Gunshot Location System detects weapons-fire eventsover large environments. ShotSpotter products range from applications for public safetyagencies and 911 dispatch centers, to fully mobile, inter-networked wireless systems for themilitary that are capable of detecting and locating many types of weapon events in variousenvironments. The system utilizes acoustic sensors deployed in a desired coverage area thatcommunicate back various base stations. The number of base stations varies based on thedeployed area's terrain. The base stations then connect to a central computer that can be locatedat a dispatch center. The sensors provide an acoustic triangulation to locate gunfire across wideareas. On average, ShotSpotter systems deploy with 15-20 sensors per square mile. ShotSpottercan use either wired or wireless sensors deployed over areas from one-half square miles up totens of square miles. In order for the system to detect a gunshot, it must be detected by three ormore sensors in the area. Since the system utilizes acoustics for its sensors; gunfire insidebuildings and vehicles will not be detected. ShotSpotter states that the system will alert togunfire events 80% of the time with accuracy of 25 meters or better. A gunshot alert usuallytakes eight to fifteen seconds before reaching the operator.

FINDINGS

Research revealed that in 2007, twenty nine thousand seven hundred sixty seven shots firedcalls were generated in the City of Los Angeles. No data was available to determine how manyof those calls were false calls or multiple calls generated for the same incident.

In 1999 the National Institute of Justice (NlJ) conducted a study in Dallas Texas by deployingShotS potter within one square mile for two months. The NIJ study revealed that deployingShotSpotter increased police workload nearly five-fold by having officers respond to every alarmincident detected by a gunfire detection system, in conjunction to the normal citizen call reports.


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Research On Gunfire Location Technologies And ShotSpotterPage 2

No current data is available to refine the results of this study. Based on the Department'sresearch, it would stand to reason that by having more activations, it would have a direct effecton caIls generated to field units. The Data also could suggest this translates to a more effectiveresponse, but not enough analytical evidence was available to conclusively determine this.In addition, systems utilizing this type of technology are susceptible to activation for items suchas jack hammers, helicopters and other ambient noise that trigger the sensors. This would alsoplaya factor.

As part of our research, Detective Bureau's Tactical Technology Unit met with a ShotSpotterrepresentative in June and August 2008. We were informed that the cost of a typical turnkeysystem for example covering 2 square miles in the Watts community, would cost approximately$500,000. Not included in the purchase cost, is the City's responsibility to provide a back-haulsolution (connection) from the base stations to a centralized computer. The system comes with aI year warranty that covers parts and labor as well as software upgrades during this period. Anextended warranty is available for 15% of total project cost per year.

As part of the references provided by ShotSpotter, the Tactical Technology Unit contacted theLos Angeles County Sheriffs Department, (LASD) Century Station who have utilizedShotSpotter for several years. As a result, the Tactical Technology Unit was invited to ademonstration of ShotSpotter at the LASD Century Station. As part of the demonstration, aShotS potter representative conducted a test by triggering the system. This was done by ignitingfire crackers near different sensors in the covered area and viewing the alarm activation from alaptop computer. The demonstration illustrated that the system was functional, that it was able toidentify the activation as a fire cracker, and determined the location within a few feet. SergeantJohn L. Gaw from the Sheriffs Department stated at the demonstration that the LASD hasbenefited from the use of this technology and is looking to expand the system's current coverage.

Based on market research, the Department discovered three additional companies that offergunshot recognition products.

The first is BBN Technologies that offers a solution called Boomerang. This system mounts onvehicles, alerts the occupants of incoming supersonic gun fire, (AK-47, .50 Caliber etc) andgives an estimate of the shooter location. The system is not designed to detect smaIl arms fire.The system is deployed by the military, but does not have a practical application on a policevehicle. The Boomerang system is not currently being deployed by a municipal policedepartment within the United States.

The second is BioMimetic Systems. The technology is currently being developed and is beingapplied to robots, with an emphasis of being deployed in a military environment. BioMimetic isnot currently commercially available.

The third is SECURES Gunshot Detection. This system is similar to the ShotS potter system, butuses different proprietary algorithms to determine gun fire. SECURES also incorporatescameras with their system.The major differences between SECURES and ShotSpotter are:


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Research On Gunfire Location Technologies And ShotSpotterPage 3

The major differences between SECURES and ShotS potter are:

SECURES does not record the audio of the of the trigger event;

SECURES does not use a multiple sensor triangulation method to determine gunshotlocation, but rather uses a single sensor location in conjunction with multiple videocameras. When the sensor is triggered, a camera points to the direction the sensor andinterprets where the gunfire came from. The operator is alerted as to which sensor wastriggered and then can view the area utilizing the camera. Detective Bureau was unableto contact an agency within the United States that is currently using and operatingSECURES system.

CONCLUSION

A gunshot recognition system can provide a force multiplier effect for law enforcement andcan improve reaction time for police to respond to shots fired incidents. Another method inwhich this technology can be deployed is utilizing a gunshot detection system in areas wherepolice cameras are present. This can prove to be a valuable tool for patrol officers anddetectives. Furthermore, a gunshot recognition system can assist law enforcement by plottinggunfire historical information to help develop strategies to address the problem. Should fundingbecome available, the Department would benefit from the use of this technology as part of anoverall comprehensive approach to reducing crime in the City of Los Angeles.


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u.s. Department of J,l,lsticeOffice of Justice Programs

National Institute 0/ Justice

National Institute of JusticeJeremy Travis Director

Issues and Findings

Discussed in this Briet The find-ings of two field studies of acousticsensing systems designed to detectthe sound of a muzzle blast from agun and, within secondsof the shotbeing fired, triangulate within somemargin of error the location fromwhich the shot was fi red, beforealerting the police about the gun-shot. The research team examinedthe effectiveness of Trilon Tech-nology's ShotSpotter system,which the local police departmenthas operated in Redwood City,California, since early 1996, andthe Alliant Techsystems Inc.'sSECURESTMystem, which police in-stalled for 2 months in a neighbor-hood with high levelsof randomgunfire in Dallas,Texas,in 1996.This Researchin Brief also outlineshow the police usedthe technologyin Dallasand what officers workingin the study sites think of gunshotdetection systems.

Key issues Anecdotal evidencefrom the media and interviews withlocal officials, police, and commu-nity members suggests that randomgunfire isconsidered a seriousproblem in many large cities in theUnited States. Random gunfire hasbeen defined as the indiscriminatedischarge of firearms into the air,which generally occurs during holi-day celebrations, during weekendsor sporting events, and often in thecontext of drinking.

Random gunfire problems aredistinguishable from other types ofshooting incidents such as urbansniper attacks, gang shootouts,domestic homicides, and revengeshootings because (1) random

continued.

December 1999

Random GunfIre Problems and

Gunshot Detection Systemsby Lorraine Green Mazerolle, COl} Watkin~ Dennis Rogan, and JamesFrank

Random gunfire is a significant prob-lem in many large cities throughout theUnited States.' Random gunfire has beendefined as the indiscriminate dischargeof firearms into the air, which generallyoccurs during the celebration of holidays,during weekends or sporting events, andoften in the context of drinking,

Communities across the United Stateshave inst ituted a variety of efforts to re-duce random gunfire problems, includingpublic awareness campaigns and the use

of technological devices to detect andalert the police to incidents of gunshotsand explosions. Generically known as gunshot detection systems, the technol-ogy includes an acoust ic sensing systemcapable of identifying, discriminating,and reporting gunshots to the policewithin seconds of a shot being fired.'

This Research in Brief summarizes thefindings of field studies of two gunshotdetection systems: Trilon Technology'sShotbpotter system, which has oper-ated in Redwood City, California, sinceearly 1996, and Alliant TechsystemsInc.'s SECURESTM system, installedfor 2 months in 1996 in a neighborhoodwith high levels of random gunfire inDallas, Texas, This Research in Briefalso outlines how the police used thegunshot detection system in Dallas andwhat officers working in the test sitesthink of the technology.

What is known aboutrandom gunfire problems

Random gunfire problems are distin-guishable from other types of shootingincidents such as urban sniper at tacks,gang shootouts, domestic homicides, andrevenge shootings because (1) randomgunfire is strictly an outdoor activity;(2) it is not usually part of other criminalactivity such as drug dealing, assaults,or robberies; and (3) random gunfireshooters do not fire their weapons to

intentionally injure or kill people.

In many U.8_ urban areas, random gunfireis considered a problem, typically involv-ing people drinking alcohol and watchingtelevised sport ing events and then walk-ing outside to fire their weapons into theair in celebration. People also tend tofire their weapons on New Year's Eve,Cinco de Mayo, Fourth of July, and othersignificant holidays. Police report thatrandom gunfire shooters believe theiractions are harmless. Shooters state that

firing their weapons in the air does notendanger lives or damage property

Policymakers, police department person-nel, city prosecutors, and communityresidents across the United States haveimplemented a variety of init iatives tocontrol serious shooting and other gun-related problems.' Yet only a few localgovernments have developed programs


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Issues and Findingscontinued ...

gunfire isstrictlyan outdooractivity;(2) it isnot usuallypart ofather criminalactivitysuch as drugdealing,assaults,or robberies;and 3 random gunfireshooters do notfiretheir weapons to intentionallyinjureor killpeople.

Residentsin communitieswith highlevelsof random gunfirelivein per-.petual fear; and law-abidingbusi-ness owners and residents freelyexpresstheir willingnesso aban-don or relocatefrom a neighbor-hood with random gunfireproblems.'

Key findings Thestudyofthe useof gunshot detectiontechnologyin locallaw enforcementled theresearchteam to four broadconclusions:

Gunshot detectionsystemsarelikelyto revealrather highcitizenunder-reporting ratesof randomgunfire problems(23 percent ofincidentsare reported).

Thetechnologyislikelyo in-crease the workloadsof policeofficers,particularlyfdepartmentsdispatch a patrol unitto everygunfireincidentdetected byatechnologicalsystem.

Gunshot detectionsystemsarenot likelyto lead to more arrestsof people firingweapons in urbansettings becauseit ishighlyunlikelythat offenderswillstayat a gun-shot locationlong enoughfor thepol ice to arr ive.

F inally,gunshot detectionsystems seem to offer the m ostpotential as a problem-solvingooland would fitnicelywithintheemerging problem-oriented polic-ing paradigm.The technologycanhelp policeidentifyrandomgunfirehot spots and developstrategiestoaddressthe problem.

Target audience Localpoliceadministrators, local governmentofficials,communitygroups,andresearchers.

tha t focus specif ical ly on random gunfirep roblems . In c ities such as Dalla s (thepolice department 's Gunshot Awareness

Program), New Orleans (Gunshot PublicAwareness Program), Redwood City(Opera tion Silent Night Program), and 51.Louis (Town Criers' Program), communityawareness campaign volunteers and thepolice work toge ther to in fo rm people ofthe dangers of random gunfi re .

Anecdotal evidence from newspaperarticles television broadcasts, andinterviews with police department off i-c ia ls ' and community members? suggeststhat random gunfire is a se rious prob lem 'in many cities. Residents in these com-munitie s live in perpe tual fear: they worrythat a stray bu lle twill k ill an innocent by -stsnde r; they feel they live in the middleof a war zone on some nights; they hide intheir homes, afra id to confront the peop ledisrupting their l ives; and law-abidingbusiness owners and residents are willingto abandon or re locate from a ne ighbor-hood with random gunfi re problems.JOOne Redwood City res ident sununed upthe problem by sta ting:

t is not uncommon to find bu lle tslodged in front porches or gutters.We are a fra id for our children .The random gunfire p roblem is a lsocostly in terms of law enforcement,property damage, and decliningproperty values.

The number of deaths f rom fi rearms-related injuries is recognized as a signifi-cant nat ional public health problem.Inthe United S ta te s in 1996, fo r example ,

there were 12.8 deaths pe r 100,000people caused by fi rearms-rela ted inju-ries. For males 15 to 24 years old, thep roblem is even more staggering : in 1996,the re were 38.9 dea ths from in ju rie s sus-tained by f irearms per 100,000 people.These data a re a compos ite o ff irearms-re la ted deaths and do no t diffe rentia te be -tween intentional and accidental firearms

injuries . The s ta ti stics a lso fail to differ-entia te between random gunfire andother criminal incidents when shots are

fi red, such as drive-by shootings, revengeshootings, shootings during drug transac-tions, and so forth. A s such, there is veryl itt le sys tematic informatiou about theextent, environmental causes, socialcontext,and societal costs of the randomgunfire problem.

The study neighborhood

The Dalla s study began with a systematicanalysis of the random gunfire problemin that c ity' s Oakcli ff neighborhood. Re-searchers reviewed videotapes of streetblock att ributes; conducted onsite obser-vations and interviews, and reviewedpolice o fficer patro l logs to develop acomprehensive view of factors contribut-ing to the random gunfire p roblem.

Oakcl iff i s composed primari ly ofresi -dentia l renta l un its mixed with lightindustrial and commercial enterprises.The community is situa ted between twomajo r commerc ia l corrido rs with a parkand la rge lake on its no rthe rn border.The majori ty of Oakcl iff residents areeconomically poor and lease their apart-ments . Fewer than 20 percent of theOakcli ff residents own their own homes,compared with a c itywide ownership ra teof m ore than 50 percent and a nationwideownership ra te of 59 percent . The aver-age month ly ren t in the Oakcliff commu-nity is 295. B y contrast, m ore than90 percent of D allas residents pay m orethan 300 in rent per month, and, ofthese renters, 41 percent pay 500 ormore per month. 13

Oakcli ff reports high levels ofrandomgunfi re : 422 cit izen reports of randomgunfire shots per 10,000 people per yearin the l-square -mile ne ighborhood a lone .Although random gunfire calls represent-ed 1.1 percen t o f to ta l police se rvice callsc itywide , they represen ted 4 .6 percent of


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total calls for service in Oakcliff dur-ing 1996. Police report no randomgunfire calls for 65 percent of Oakcliff

streets (similar to call patterns forother crime problems). However, asmall percentage (5.5 percent) of thestreets generated nearly 45 percent ofall random gunfire calls.

Researchers examined the social andphysical attributes of Oakcliff streetblocks that experienced random gun-fire calls for service. These results arespecific to the Oakcliff neighborhoodand cannot be generalized to Dallas orany other community in the UnitedStates. The research shows predomi-nately residential street blocks thathad higher property values or rentalfees experienced more random gunfirecalls for service than Oakcliff streetblocks with lower property values orthose comprising commercial proper-ties or vacant blocks. Random gun-fire calls were not generally a problemon Oakcliff street blocks that had alarge proportion of properties in disre-pair or on streets with high levels of

physical decay, a lot of foliage, or onblocks with relatively high levels ofcalls about serious crime problems.

Random gunfire calls were moreprevalent on street blocks that gener-ated a substantial number of prowler,suspicious person, and disturbancecal ls. This suggests other types of sus-picious and unruly behavior are prob-ably correlated with Oakcliff's randomgunfire problem.

The study findings are somewhatinconsistent with crime and placeresearch that finds signs of decay areindicative of other social and crimeproblems. Nevertheless, the studyfindings suggest random gunfire maybe a unique type of crime problem notnecessari ly part of, nor indicative of,systemic decline and decay on a street

block. The study results are consistentwith Dallas police officer perceptionsthat random gunfire problems occur

in Oakcliffs residential areas, specifi-cally in the context of people drinkingin their homes and backyards, watch-ing sporting events, and celebrating.

Gunshot detection systemsWhat are they? Acoustic gunshotdetection systems are designed to pickup the sound of a muzzle blast from agun and, within seconds of the shot be-ing fired, pinpoint or triangulate withinsome margin of error the gunshot's

location, before alerting the policeabout the shot being fired.

Manufacturers of gunshot detectionsystems expect the technology to in-crease the ability of the police to get tothe scene of random gunfire quickly,increase the number of people arrestedfor firing weapons, and reduce the det-rimental effects (injuries, fear, disin-vestroent) of shots being fired in urbansettings. Community advocates ofgunshot detection systems believe thetechnology can deter would-be shoot-ers and improve the quality of life intheir neighborhoods.

AIliant Teehsystems Inc. 'sSECURES. The gunshot detectionsystem installed in Oakcliff wasdeveloped and demonstrated byAlIiant Techsystems Inc. (AT ) andsubsequently marketed as SECURES(System for the Effective Control ofUrban Environment Security).

SECURES identifies the locat ion andtime of gunfire in a specified targetarea through a series of small units (oracoustic sensor modules) mounted onutility poles. These battery powered pole units, which are about the sizeof a video cassette, are composed of anacoustic sensing element, gunshotidentification 'electronics, and a trans-

mitter. Eighty-six pole units wereerected in the l-square-mile Oakclifftarget area to provide adequate system

coverage for the 2-month studyperiod.

The pole units are designed to acousti-cally identify gunshots and transmitthat information to a police dispatchcenter through a network of transmit-ters and receivers connected to thelocal phone system. The gunshot loca-tion and time are transmitted to a per-sonal computer in the dispatch centerin less than 2 seconds, and the gunfireinformation is displayed on a comput-erized map, enabling dispatchers torelay the information to officers onthe street.

The SECURES prototype alerts policedispatchers to the location of the firstpole unit to detect a shot. ATI claims,however, that subsequent enhance-ments to the system triangulategunfire alerts such that real-timeinformation from responding pole unitspinpoint the precise locat ion fromwhich the shot was fired, ATI claimsthis type of triangulation procedureCllJ1 pinpoint 99 percent of gunshotswithin a 65-foot radius of the firingspot, 88 percent of gunshots within30 feet, 63 percent of gunshots within20 feet, and 35 percent of gunshotswithin 10 feet.'?

Trilon Technology's ShotSpotter.The ShotSpotter gunshot detectiontechnology installed in Redwood Citywas designed and demonstrated by

Trilon Technology. The ShotSpottersystem, installed in the 1-square-mileRedwood Vil lage area since early1996, consists of eight acoustic sen-sors, a central computer located in theRedwood City Police Department'sdispatch center, and gunshot detectionand location identification software.


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The acoustic sensors include micro-phones, acoustic sensing elements,and gunshot identification electronics.

The sensors instal led in Redwood Vil-lage resemble birdhouses and heatingvents and are enclosed in weatherproofcontainers approximately 1 cubic footin size. The acoustic sensors detectmuzzle blasts from gunfire or otherexplosions and then transmit thesound of the gunfire via telephoneline to a central computer located ina police department dispatch center.

Parameter settings in the ShotSpottersoftware determine the system's level

of sensitivity: if the thresholds are setquite high, background noise is lessoften identified as gunfire. Conversely,if the thresholds are set quite low,more background noise can be de-tected as gunfire, increasing the poten-tial that extraneous noises will beincorrectly identified as gunfire.Once the sensors detect a sound andtransmit the information to the centralcomputer, the ShotSpotter softwarediscriminates against most other com-

munity sounds (such as car backfires,jackhammers, thunder, and barkingdogs) and pinpoints the location of thegunfire or explosions. Gunshot eventsare displayed on a computer map inthe police dispatch center within ap-proximately 15 seconds of the noisebeing made. The computer map distin-guishes property boundaries, includingfront or side yards, curbsides, or streetcomers.

Determination of the precise location

of gunfire events is conducted througha series of iterations of triangulationalgorithms. The system can generatean overview map that presents thelocations of historical shootings todiscern patterns in space ortime. TheShotSpotter computer can be placed ina dispatch center with stand-alone or

integrated outputs, or i t can be placedat a remote site.

The ShotSpotter system stores allwaveforms for every deiected gunfireevent and 6 seconds of audio fromeach detecting acoustic sensor(2.3 megabytes each). As such, asignificant amount of system memoryis required when numerous gunfireevents occur simultaneously or whenmany noises are relayed to the systemin quick succession (during NewYear's Eve or Fourth of July, for ex-ample). Once the ShotSpotter systemdetects a shot and reports the location

on the computer screen, dispatcherscan play back the fi-second snippet ofsound from any sensor to assist themin determining what they believe to bethe true source of the sound: fire-cracker string, mnltiple gunshots,shotgun blast, or car backfire. Theability to play back the sound of theapparent gunfire alert is unique toShotSpotter and offers police an oppor-tunity to determine whether they thinkthe sound is in fact gunfire.

Do they work?

The Redwood City Police Department,the San Mateo County Sheriff 's Office,and Trilon Technology agreed to sub-mit the ShotSpotter system to a seriesof field trials. The police departmentapproved the firing of test blanks un-der controlled conditions to measurethe performance of the technology inJune 1997. 22 Similar permissions werenot granted during the field test of the

SECURES system in Dallas.

The evaluat ion team worked with po-lice department personnel to selectweapon types, the number of shots tobe fired, and the times and locat ionsfrom which test shots would be fired.The police suggested that three

weapon types be used: an MP5 assaultrifle, a .38 caliber pistol, and a 12gauge shotgun. The police department

notified community residents andbusiness owners about the inordinatenumber of sbots that would be firedduring the field test to avoid calls fromconcerned citizens about the gunfire.All test shots were fired from side-walks at intersections or along streetblocks.

The evaluation team assessed theperformance of the ShotSpotter systembased on three outcomes:

Did the ShotSpotter gunshotdetection system annunciate andtriangulate the shot location(true positive)?

Did ShotSpotter fai l to annunciateor triangulate the shot location(false negative)?

What was the location errorfromthe true shot location to the triangu-lated shot location (in feet)?

Exhibit 1 presents the results of the

field trial , examining the breakdown ofresults for each weapon type and eachof the evaluation outcomes annuncia-tion and location error).

Of the 31 field trial events, 8 testedthe MP5 assault rifle, 13 testedthe .38 caliber pistol rounds, and10 tested the 12 gauge shotgun. Thetechnology. armunciated shotgun testsat the highest rate (90 percent), fol-lowed by pistol tests (77 percent), andthe MP5 assault rifle (63 percent).

Overall, the ShotSpotter technologyannunciated nearly 80 percent of thetest shots (true positives) and failedto annunciate random gunfire eventsabout 20 percent of the time (falsenegatives). It should be noted that themuzzle blast waveform from blankrounds is different from the muzzle


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Exhibit 1 R edw ood C ity s S hotSp otter F ield Trial R es ults

Total Number Percent of Medianof Gunfire Shots Location

Events Annunciated Error In Feet

MPS Assault Rifle 8 63 27.0

.38 Caliber Pistol 13 77 25.0

12 Gauge Shotgun 10 90 23.5

blast waveform from live rounds; it canbe difficult for gunshot detection tech-nologies to discriminate between thetwo. 2 Therefore, the ShotSpotter tech-nology should annunciate significantlymore than 80 percent of gunfire inci-

dents when live rounds are fired underreal-life conditions.

The ShotSpotter system identified andtriangulated random gunfire eventswithin about 25 feet of the true shotlocation. Shotgnn events had the low-est median locat ion error of 23.5 feet;pistol events were correctly identifiedwithin 25 feet of the true shot location;and the MP5 assault rifle tests wereidentified within 27 feet of the correctfiring location.

Random gunfire alerts andpolice responseCitizen reporting of a gunshot fired istypically dependent on (1) the cit izenhearing the shot, (2) the citizen identi-fying the noise to be gunfire, (3) thecitizen making the decision to call thepolice shortly after the shot has beenfired, and (4) the citizen telling thepolice the location from which the

shot was fired. Prior to the introduc-tion of the gunshot detection system inDallas, the police took approximately20 minutes to dispatch a citizen callahout random gunfire and an addi-tional 5 minutes to respond (arrive onthe scene) to citizen alerts in the studyarea. This response pattern w as con-

sistent with the low priority responsethe police department placed on ran-dom gunfire calls. Officers typicallystayed on the scene of a call for about15 minutes. In total, citizens randomgunfire reporting calls took approxi-

mately 40 minutes to clear from thetime the call was placed to the timethe officer concluded the investigationof the scene.

The introduction of gunshot detectionsystem s in D allas rem oved the citizencontingencies influencing randomgnnfire reporting and somewhatchanged the patterns of police re-sponse. During the field trial in Dallas,the police received 188 alerts of gun-fire from the SECURES system and49 citizen calls. They subsequentlydispatched 151 of the SECURESalerts and 39 of the citizen calls.'The police dispatched both citizencalls and SECURES alerts quickerduring the field trial (13 minutes and18 minutes, respectively) than beforethe introduction of the gunshot loca-tion system. The police continued totake about 5 minutes to arrive onthe scene for a citizen alert and about7 minutes for a SECURES alert. Once

on the scene, the police cleared theci tizen call quicker (12 minutes) thanbefore the field trial , yet they tooksignificantly longer to clear theSECURES alert (19 minutes). It ispossible the police spent less time oncit izen calls about random gunfire dueto the greater total number of random

gunfire alerts generated by the gunshotlocation system and the subsequentincrease in the number of dispatches

for random gunfire alerts. Overall,the Dallas police received and clearedcitizen random gunfire calls in about30 minutes, and they received andcleared SECURES alerts in about44 minutes during the field trial.

Using gunshot detectionsystemsDuring the 2month Dallas field trial,the police made 190 radio runs (151SECURES alerts and 39 citizen random

gunfire calls) in the Lsquare-mileOakcliff community. The number ofcitizen calls during the field trial wassimilar to the average number of citi-zen calls to the police about randomgunfire incidents prior to the fieldtrial. As such, the extra SECURES-dispatched radio runs over and abovethe cit izen-initiated calls during thefield trial represent an almost fivefoldincrease (190/39=4.87) in the numberof police dispatches to random gunfire

problems.Alliant Techsystems lnc. claimsSECURES correctly identifies 88percent of all shots whose propagationpath to the microphone is not blockedby a close building. The acousticdatabase used to support this claimwas collected by ATI during testsconducted at military proving groundsand police test ranges and when liverounds were fired in open field envi-romnents as well as among building

structures.e? T hu s, assu ming the SE~CURES true-positive rate is correct,the field trial suggests that many ran-dom gunfire incidents are not reportedby citizens.


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4. Interview with Dallas Police Departmentpersonnel, Dec. 14, 1996.

5 . K en ne dy. D av id , A nn e P ie hl,and. Anthony

Braga. Youth Violence in Boston: Gun M ar-kets, Serious Youth O ffenders, an d a U seReduction Strategy, Laso and ContemporaryProblems. 59 (1) 1996: 147-159; also seeS hen nan , L aw ren ce W.,and D en nis P. R og an , Effects of G un Seizures on G un Violence: 'H otS po ts ' P atro l in K an sas C ity :' Justice Quarterly12 (4) 1995: 673-693.

6. A ssociated Press, Ringing in '9 7 WithBullet s, Bombs ; Police . F ire Off ic ia ls Preparefor il lega l New Year's Revelry, The LubbockAvalanche D ec. 3 1, 1 99 6; s ee also P im en tal,B en jam in , R ed wo od C ityOKs Test of Systemto Locate Gunshots: First City to U se the N ewSensors, The San Francisco Chronicle Aug.30, 1995: A16; Support Builds for GunshotLocator. The San Jose M ercury N ew s Feb. 12,1997: IB and 48.

7. CBS Evening New N ew H igh Tech H elpfor Tracking Down Criminals , CBS EveningNews Jan. 17, 1996; A BC Ev ening N ew sR ed wo od C ity C ou ncil Votes to P urch ase

Shcigpotter after Successful Test, ABCEvening New Ju ly 2 8, 1 99 7; Chan nel 10San Diego Does ShotSpotter Really Work?Channel 10 San Diego A ug . 2 7, 1 99 8.

8. Based on persona l communica tions, in te r-v iew s, an d d iscu ssio ns w ith D allas P olic eD ep ar tm en t an d R ed wo od City P olice D ep art-m ent representatives in 1996 and 1997.

9. Focus groups conducted w ith Redw ood Cityresidents in June 1997.

10. Persona l communication with RedwoodC ity res id en ts in 1 99 7.

11. N atio nal Vital S tatistics Rep or t. 4 7 ( 19 )June 30, 1999.

1 2. U .S . Cen su s B ure au , Census of Populationand Housing : General P ro fi le for the UnitedStates Wash in gto n, D C: U .S . D ep artm en t o fC om mer ce. U .S . Cen su s B ureau , 1 99 0.

1 3. U .S . Cen su s Bu reau , Census of Populationand Housing : Genera l P ro fi le for Dal la s CityTX Washington , DC: U.S . Depar tment ofC om merce, U .S . C en su s B ur eau , 1 99 0.

14.. S hen nan , L aw ren ce, P atrick G ar tin , an dM ich ael B uerg er, H ot S po ts o f P red ato ryCrime, Criminology 27 (1) 1989: 27-56; alsosee Watk in s. C. , E nv iro nm en tal C orrelates o fRandom G unfire: A Block Level A nalysis o f

the Rela tionship between Random GunfireProblems and Physical and Soc ia l Inc iv ili ti es ,unpublished doc tora l d is se rt at ion, Univers ity ofCincinnati. 1998.

15. Oakcli ff is a des igna ted dry neighbor-hood. As such, no p ublic bars or liquor storesopera te in the neighborhood . However, p rivated rin kin g c lu bs ex ist inOakcliff, p rimarily inresidential areas.

1 6. Watk in s, C., E nv ir on men tal C orr elates o fR an do m G un fir e: A B lo ck L ev el A naly sisofthe Relationship between Random Gunfi reProblems and Physica l and Soc ia l Inc iv ili ti es .II

17. Eck, John , and David Weisburd, Crim ePlaces in Crime Theory, in Crime and Placeed. J.E. Eck and D . Weisburd, M ousey, N Y:Criminal Jus ti ce Press , 1995; Mazeroll e,

L or rain e G ree n, J an R oeh l, an d C olleenKedleck, Control ling Soc ia l Disorder UsingCivil Remedies: Resul ts f rom a RandomizedFie ld Exper iment in Oakland , Cal ifornia, CivilRemedies and Crime Prevention: Crime Preien-tionStudies v ol. 9 , M on sey, N Y: Cr im in al Ju s-tic e P res s, 1 99 8: 141-160; Skogan, Wesley,Disorder and Dec line : Grime and the Spi ra l toDecay in American Citit;S New York: FreePr ess, 1 98 9; Tay lo r, R alp h, ''S ocial O rd er an dDisorder of S tree t Blocks and Neighborhoods:Eco logy, Micro Ecology and the Sys temicModel of Social Disorganization, Jou:rnal ofResea rch in Crime and Del inquency 34 (1997):113-155; Wilson, J.Q., and G . K elling, Bro-

ken Windows, The Atlantic MOnJ;hi.y March1982: 29-38.

18. ATI person nel in an O ct. 30, 1996, inter-v iew sa id th e p ole u nits c ost ab ou t S l,7 50eac h, an d th e b atte ries las t ab ou t 2 m on th s.T hey su gg est th at a pp ro xim ately 8 0 p ole u nitsare required to cover a Lsquare-mile area.To lease , SECURES wil l cos t approximate ly 5,500 for each square mile covered permonth. This cost covers the lease of 100 poleu nits, 3 rep eater s, 1 b as e statio n, an d m ain te-nance on the system . The quoted cost does notcover ins ta ll ation and assumes medium densityhousing.

1 9. A llian t Tech sy stem s In c. failed to in -stall th e trian gu la tio n en han cem en t o f th eSECU RES system at the time of the field trial.O fficers w ere d isp atch ed to th e first p ole u nitth at reco rd ed a sh ots-f ired in cid en t ra th er th ana trian gu lated lo catio n id en tified th ro ug h as eries o f d etec tio ns b y n um ero us p oleunits.(Based on an O ct. 30, 1996. interview w ithATI personnel.)

7

20. Muzzle b last s f rom gunfire have d is tinc tivew av ef orm s, a s d o th e so un dsfrom other similarsources . However, the set ting parameter s dete r-m in e w hat lev el o f e xtr an eo us n ois ewill trip

the system . H ence, the less sensitive the pa-ram eter settin gs , th e less lik ely it is th at jack -h am mers, th un der, an dcar backfires will setthe system off (false positives). Alternatively,th e m ore sen sitiv e th e p ar am eter se ttin gs, th emore likely it is th at ex tr an eo us n oise will tripthe system.

21. The system can be its own opera ting sys temwithin the dispatch center, orit can he linkedinto the d ispa tch sys tem's opera ting sys tem.

22. T he o rig in al p ro po sal w as to d isch arge liv erounds of ammunit ion. However, numerousd iscuss ions with the police chie f, h is adv iser s,an d p erso nn el f ro m Trilo n Tech no lo gy led toan agreem ent to discharge blanks as op posed toliv e ro un ds . A lth ou gh th e am plitu de w av esgenerated by blanks are not identical to theampli tude waves generated by l ive ammunition ,they w ere close enough for the blanks to serveas adequate substitutes.

23. Persona l communica tion with John Coll ins,ed., Association of Firearm and Toolmark Ex-aminers Journal Nov. 9. 1999.

24. Compara tive response timedata w ere n otread ily av ailab le in R ed wo od City. C alls w ereplaced to b oth th e S an M ateo Co un ty S her if f'sO ffice an d th e Red wo od C ity P olice D ep ar t-m en t. O nly s elected calls w ere av ailab le fo ran aly sis fr om th e p olice d ep ar tm en t d ata,co mp ro misin g a co mp lete an aly sis o f th eircall data.

25. Meeerol le , Lor ra ine Green , Cory Watkins,Dennis Rogan, and Jam es Frank, U sing G un-sho t Detection Sys tems in Police Depar tments :The Im pact on Police Response Times andOfficer Workloads, Police Qwzrterly 1 (2)1998: 21-49.

26.lbid.

27. There w ere 151 SECU RES alert eventsthat were not linked at an y tim e to a citizen

cal l and resulted in a radio run. There were3 9 citizen a ler t ev en ts d urin g th e stu dy p er io dresulting in 39 radio runs. Of these 39 citizen-in itiated rad io ru ns , 1 0 in clu ded a S ECU RESale rt that was re fe renced to a c iti zen call .Tha t is . the call -t aker and /or d ispa tcher linkedthe SECU RES call to the citizen call and dis-patched it as a citizen call. A s such, a totalof 190 radio runs for randomgunfire alertsw ere made during the study period: 151 that


13/13

involved the technology only, 29 tha t involvedc it izen cal ls only,and 10 that were dispatchedas cit izen calls but involved a combination ofc itiz en s an d SE CU RE S initia ting th e a le rt.

28. S ee M az ero lle etal., Using GunshotDetection Systems in Police Departments:T he Im pac t o n P olic e R esp on se Tim esandOfficer Workloads.

29. Page and Sharkey, SECURES: System forRepor ting Gunshots in Urban Environments :170.

30. Ibid. : 162.

31. T he research team cannot provide anyin de pe nd ent m ea su re o f t his cla im ed fals e-p os itiv e ra te b eca us e n o fie ld te st o f S E CU RE Swas conducted in D allas where blank or live

ro und s w ere fire d u nde r fie ldtrial conditions.

32. T he 2 3-p erc en t c itiz en re po rtin g ra te w asreached in th e fo llo win g m an ne r: u sing th e

Lorraine Green Mazero lle , Ph.D., is anassoc ia te professor in the Div is ion ofCriminal Jus tice a t the Univers ity ofCincinnat i. CoryWatkins, Ph.D., isass is tant p ro fessor in the Depar tment o fCrim inal Justice an d L egal S tud ies atthe Univers ity of Cen tra l F lo rida. Den-n is Rogan . Ph.D., is p residen t o f S te tis -t ical Analysis forLaw EnforcementStrategies in Bowie. Maryland. JamesFrank. Ph.D., is assoc ia te pro fessor inth e D ivision o f C rim in al Ju stice at theUniversity of Cincinnat i. The studyrep orted in this Researc h in B riefwas

baseline of151 SECURES-in iti at ed red tc runsdur ing the 2-month f ie ld trial, researchers ap-plie d th e 12 -p erc en t e rror ra te to id en tify 1 69est imated shots . The 39 c it izen-ini ti ated radio

runs over the test period w ere divided by the169 estimated inc iden ts to ident ify the23-percent reporting rate(39/169xlOO).

33. Officers in b oth citie s b eliev e th ey te nd torespond quicker to gunshot detec tion sys temcalls than cit izen-generated calls . Some offic-ers explained they merely want to cle ar th e c allquickly and m ove on to the nextcall. It i s rea -s on ab le to ex pe ct th at th e p olice w ou ld s pe ndmore time handling calls that they thoughtworthwhile. Possible explanations for theseapparent contradictory findings: (1) the police' 'leave open the SECURES alerts longer be-ca us e th ere is n o c itiz en w aitin g totalk with

them when they arrive, and they m ove onto thenext call; (2) police deal with a cit izen-ini tiateda le rt in a more expedient manner becauseth ere is a s et o f s ta nda rd pro ce du re s to fo llow

supported by grant 96-MU-MU-D018fromthe National Institute of Justice tothe University of Cincinnati.

T he au tho rs are ind ebted to sup port fromthe Dallas Police Department, the Red-wood City Pol ice Department, All iantTechsystems Inc., and Trilon Technology.Please address all correspondence toLorraine Green Mazerolle, AssociateProfessor, Division of Criminal Justice,University of Cincinnat i, PO Box 210389,Cincinna ti, OH 45221-D389. Phone-513-556-5830, fax 513--556-3303, ore-mail [email protected].

(l,e., vis it the cal le r. e li ci t information f romthem, and then take alook a rou nd ). T his is no tthe case for the SE CU RE S alerts. T he policeget to the scene and then have to knock ona

fe w d oo rs to g athe r in form atio n ab ou t thegunfire.

34. Chatter ton. Michael . Targe ting Commu-nity Beat Officers: Organisational Constraintsand Resistance, P olicin g an d S ociety 3(1993): 189-203.

3 5. O ne c av ea t h ere is th e in itia tiv e rec en tlya nn ou nc ed b y Trilo n tec hn olo gy c alle d The Communica tor, which is l inked with theShotSpotter system to systematically place callsto ho us eh old s an d bu sin es se s w ithina closegeographic area of the gunfire a le rt to informthem of the incident. f the c it izen has informa-tion, he or she can press a key on a touch-toneph on e to b e im me diate ly tra ns fe rre d to a liv edispatcher.

Findings and conclusions of the researchreported here are those of the authors and donot necessari ly ref lect the official pos ition orpol ic ies of the U.S . Depar tment ofJust ice.

The National Institute of Justice is acomponent of the Office of JusticePrograms, which also includes the BureauofJustice Assistance. the Bureau ofJusticeStatistics, the Office of Juvenile Justice andDelinquency Prevention, andthe OfficeforVictims of Crime.

This and other NIJ publications can befound at and downloaded from the NIJWeb site (http://www.ojp.usdoj.gov/nij).

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REPORT TO PUBLIC SAFETY COMMITTEE ON A GUN-SHOT LOCATION SYSTEM KNOWN AS "SHOTS POTTER"