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Automatic Collision Notification Field Test


National Highway Traffic Safety Administration

Guest Editor

John H. Flint, BS

University of Virginia

Charlottesville, VA

Commentary: Automatic Collision Notification:

Ready or Not, Here It Comes

Herbert G. Garrison, MD, MPH, Department of

Emergency Medicine

Paul R. G. Cunningham, MD, Department of


The Brody School of Medicine

East Carolina University

Greenville, NC

Section Editors

Joan S. Harris

National Highway Traffic Safety Administration

Washington, DC

Knox H. Todd, MD, MPH

Rollins School of Public Health

Emory University

Atlanta, GA

Federico Vaca, MD

Division of Emergency Medicine

University of California–Irvine

Center for Health Policy Research

Irvine, CA

Reprints not available from the editors.47/1/118454doi:10.1067/mem.2001.118454

whereas in other regions, rotor wing aircrafthave decreased motor vehicle fatalities by asmuch as 52%.3 Thus, rapid response andretrieval of those injured in motor vehiclecrashes plays a role in reducing morbidity andmortality of the victims.


Working with Veridian Engineering, JohnsHopkins University Applied Physics Labora-tory, and other partners, the NHTSA sponsoredthe ACN demonstration in Erie County, NY,from 1995 to 2000. The focus of the projectwas to demonstrate that an ACN system wastechnologically feasible, that it could distin-guish potentially serious personal injurycrashes from minor property-damage–onlycrashes, and that it could decrease crashnotification times.

For the ACN system to provide faster andsmarter emergency medical responses, itshould be able to:

1. Determine that a motor vehicle has beenin a collision;

2. Notify emergency response personnelof the collision and the vehicle location;

3. Provide information concerning crashseverity; and

4. Establish a voice link between the vehi-cle and emergency response personnel.

The ACN system developed for the projectconsisted of in-vehicle hardware and soft-ware that detected the crash and communi-cated with the dispatch center equipment.The hardware consisted of a set of crash sen-sors, a locator using Global Positioning Systemtechnology, and a wireless communicationssystem. After a crash of sufficient severity, theACN system sent crash notification informa-

Automatic CollisionNotification Field TestSummary

[National Highway Traffic Safety Admin-istration. Automatic CollisionNotification field test summary. AnnEmerg Med. October 2001;38:453-454.]

From 1995 to 2000, the National HighwayTraffic Safety Administration (NHTSA) spon-sored an initiative to create and operate anAutomatic Collision Notification (ACN) sys-tem on a demonstration basis in a rural areato provide faster and smarter emergencymedical responses in an attempt to save livesand reduce disabilities from injuries. Thisarticle is a brief summary of that demonstra-tion project.


Motorists involved in serious crashes are atheightened risk if the medical care they re-ceive is delayed because of slow discovery,notification, or response times. Drivers inrural areas are at particularly high risk. Inrural Missouri, Brodsky1 found that only 39%of calls made to alert emergency medical ser-vices (EMS) of a collision came within 5 min-utes of the collision, whereas in urban studyareas 90% of alerting calls arrived in lessthan 5 minutes. Additionally, Brodsky reportedthat nearly 60% of all fatal crashes occur alongroadways classified as rural.

In West Germany, being within 15 min-utes of a Level 1 trauma center by ground orair transport decreased the mortality result-ing from motor vehicle crashes by 25%,2

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National Highway Traffic Safety

Administration (NHTSA) Notes

Page 2: Automatic collision notification field test summary

tion to the Public Safety Answering Point andthen established voice contact with vehicleoccupants.

The dispatch center equipment receiveddata from the ACN system and displayed it ina relevant manner for the EMS responders ordispatchers. It accomplished this task by gen-erating a map showing the location of thecrash and presenting characterizing crashdata, such as speed, direction of force, andvehicle orientation.


The ACN system equipment was installed inapproximately 800 vehicles. The system de-tected several crash characteristics, includingthe Delta V (the change in vehicle velocityfrom immediately before to immediately afterthe collision) with 87% accuracy, principaldirection of force with 100% accuracy, rolloverstatus with 93% accuracy, location within100 meters with 73% accuracy, and headingwithin 15 degrees with 100% accuracy. Ad-ditionally, the system detected crashes 95%of the time and did not report any subthresh-old crashes. Although this level of accuracy isnot sufficient for commercial implementation,it appears that correctable features causedmost of the inaccuracies. This led the investi-gators to conclude that commercial-levelreliability would be attainable with an ACNsystem.

The average notification time in NewYork State for fatal crashes is 7 minutes asreported by NHTSA’s Fatality Analysis Re-porting System (FARS). In sharp contrast, theaverage collision notification time for ACN-equipped vehicles during the demonstrationwas 44 seconds. This short notification timewas a result of the ACN system instantane-ously deciphering the severity of the crash,predicting likelihood of injury, and contact-ing EMS if needed. The ACN system thus cir-cumvented the need for an observer to wit-ness the crash or predict need for medicalassistance.

The fact that there were only a small num-ber (22) of above-threshold crashes in thevehicles equipped with ACN during the studyperiod makes it difficult to draw strong sta-tistical conclusions. However, preliminarydata strongly suggest that ACN has the abil-ity to reduce the EMS notification times, pos-sibly by substantial amounts.

crash forces, let officials know whether anypassengers are injured. Such is the vision ofthe futuristic “intelligent” transportationsystem (ITS).1

The mayday black box that detected thecrash in the scene from the future is properlycalled an automatic collision notification(ACN) system. The ACN systems are anessential part of the ITS vision, especially forrural America.2 The rationale for a rural ori-entation for ACN is simple: most crashdeaths occur in rural areas with low popula-tion densities.3 The remote location of manysevere crashes makes it difficult to achievethe paramount trauma system goal of keep-ing a brief interval between the time of thepatient’s injury and the time of arrival at atrauma center. The ACN systems will, theo-retically, facilitate discovery of the crashalmost simultaneous with its occurrence,thus giving injured passengers a betterchance for survival. Conversely, if the ACNsystem detects a non-injury crash, costlyresources are saved from unnecessary use.

The recently reported ACN system fieldtest, which was sponsored by the NHTSA, is acritical step toward achieving the ITS vision.4

The equipment used to configure the ACNsystem evaluated in the field test includedcommercially available accelerometers todetect and measure crash forces, cellularcommunications equipment, global position-ing satellite devices, and automated maptechnologies. This hardware was integratedwith software that analyzed crash forces inreal time to determine when thresholds indi-cating serious injury were reached. Thisinformation was relayed immediately to 911public safety answering points (PSAPs) in thefield test region.

The field test provided preliminary answersto important questions about ACN feasibilityand reliability. By the end of the project, theACN systems had been installed in more than800 privately owned vehicles. Those vehicleshappened to be involved in 70 crashes, 22 ofwhich were above crash force thresholds fornotifying the PSAPs. The feasibility of usingACN systems to detect crashes, determinewith accuracy the location of the crash, andprovide notification to appropriate PSAPswas demonstrated clearly.

Whereas the field test demonstrated thatit is feasible to have ACN systems detectcrashes and notify PSAPs, questions about



Key results reported in the NHTSA’s “Auto-mated Collision Notification Final Report”(October 31, 2000) include:

1. ACN technology works.2. It reduces response times.3. The EMS community was able to learn

and use the ACN system.4. ACN systems can inform EMS of:

a. Occurrence of a crashb. Accelerations involved in a crashc. Location of a crash

5. ACN systems potentially reduce com-munication errors by integrating voice anddata systems.

6. Integration of commercial ACN systemswith the public infrastructure is crucial toachieving maximum ACN benefits.

For a complete copy of “Automatic Col-lision Notification Final Report,” October 31,2000 (DOT HS 809 303) and “Automatic Col-lision Notification Field Operational TestEvaluation Report,” February 2001, contactArthur A. Carter, NHTSA, Office of VehicleSafety Research, 202-366-5669, or send a faxor e-mail request to 202-366-7237 [email protected]. Brodsky H. The call for help after an injury road acci-dent. Accid Anal Prev. 1990;25:123-130.

2. Trunkey DD. Trauma. Sci Am. 1983;249:28-35.

3. Baxt WG, Moody P. The impact of a rotorcraft aeromed-ical emergency care service on trauma mortality. JAMA.1983;249:3047-3051.

Commentary: AutomaticCollision Notification:Ready or Not, Here ItComes

[Garrison HG, Cunningham PRG. NHTSACommentary: Automatic Collision Notifi-cation: ready or not, here it comes. AnnEmerg Med. October 2001;38:454-455.]

Some day in the future, after a long nightshift, tired physicians (and all other drivers)will be able to nap comfortably behind thesteering wheel of their car as it is whiskedsafely and automatically along the highway.If their car is in a collision when it is offautopilot, its “black box” will immediatelynotify local public safety agencies of thelocation of the collision and, using detected

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