| *TRAFFIC TECH* |
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|                | Technology Transfer SeriesNumber 91, April           1995 |

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## MODEL   MINIMUM PERFORMANCE SPECIFICATIONSFOR   LIDAR SPEED MEASUREMENT DEVICES

 

Within the past few years the   use of lidar speed measurement devices for speed limit enforcement by police   agencies has steadily increased. LIDAR (LIght   Detection and   Ranging) is more commonly known as a   laser speed measurement device. To insure the devices are accurate and reliable,   there is a need for independent testing. To fill this need, the International   Association of Chiefs of Police (IACP), requested that the National Highway   Traffic Safety Administration (NHTSA) establish minimum performance specifications   for lidar speed measurement devices.  

How   Lidar Works

Using a very narrow beam, lidar   transmits infrared light pulses to a target. In speed monitoring tasks, this   narrow beam allows a lidar operator to target a specific vehicle for speed measurement.   The light pulses travel to the target and back again. Measurement of the elapsed   time of the light beam to reach the vehicle and return computes the vehicle's   distance from the operator. Changes in the distance provide the vehicle's speed.   The device is often called a laser speed gun because the source of the lidar   light is a laser.

 Lidar   Minimum Performance Specifications

At NHTSA's request, the National   Institute of Standards and Technology (NIST), US Department of Commerce, developed   model performance specifications and testing protocols for laser speed measurement   devices. Several years ago, NIST also developed model performance specifications   for police traffic radar. The results of the current lidar project, *Model   Minimum Performance Specifications for Lidar Speed Measurement Devices*   are now available. Completed in December 1994, these model specifications are   being widely distributed to law enforcement agencies and highway safety officials.   They are also available to the public. 

The U.S. Department of Health   and Human Services, Food and Drug Administration's Center for Devices and Radiological   Health (CDRH), has rated the lidar speed units currently on the market as Class   I devices. Class I is the lowest classification of a laser product in terms   of relative potential risk. NHTSA recommends that law enforcement agencies use   only lidar speed instruments that have been rated Class I by CDRH. 

Testing

The IACP, with NHTSA support and   funding assistance, is establishing lidar testing laboratories at two universities.   Both of these laboratories are currently testing police traffic radar and are   being equipped to test lidar.  

The International Association   of Chiefs of Police will manage testing of lidar units to determine if they   meet the minimum performance specifications. Devices that meet the specifications   will be placed on the IACP's Consumer Products List for Radar and other speed   measurement devices. This list, which is published and periodically updated   by the IACP, provides law enforcement agencies and highway safety officials   with the name of each Radar and lidar device that meet the minimum performance   specifications. 

Training

In 1995, NHTSA will publish and   distribute a model basic operator training course in lidar speed measurement.   In modular form, the course includes 24 hours of formal classroom instruction.   After successfully completing a written exam, a trainee must also successfully   complete 16 hours of supervised field practice, leading to certification. Course   topics are:

- Basic principles of lidar speed measurement
- Major components and functions of the specific lidar instrument used by     the trainee's agency
- Basic skills in operating the lidar instrument
- Laws, court rulings, regulations, policies and procedures affecting lidar     speed measurement and speed enforcement in general
- Basic skills in preparing and presenting courtroom testimony about lidar     speed measurement and enforcement.

NHTSA believes that lidar speed   measurement is an effective tool for speed limit enforcement. Lidar provides   an additional means for increasing the effectiveness of speed enforcement programs   and enables police managers and other highway safety officials to better deter   speed related crashes. Purchasing lidar units based upon their perfor-mance   capabilities will help get the best equipment in the hands of law enforcement   officers. 

Together, the testing process   and training program will help assure law enforcement agencies, the public and   the courts, that lidar is a safe, reliable, and accurate way to measure vehicle   speed. These specifications were developed in accordance with the joint NHTSA   and FHWA *Speed Management Work Plan* issued January 1995.

For a copy of *Model   Minimum Performance Specifications for Lidar Speed Measurement Devices*   or for more information about this program, contact Bernard J. Moran, Police   Traffic Services Division, NHTSA, NTS-41, 400 Seventh Street, S.W., Washington,   DC 20590, (202) 366-4292,   or send a fax to (202) 366-7721. 

 

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 U.S. Department   of TransportationNational   HighwayTraffic   SafetyAdministration400 Seventh Street, S.W. NTS-33Washington, DC 20590

Traffic   Tech is a publication to disseminate information   about traffic safety programs, including   evaluations, innovative programs, and   new publications. Feel free to copy it as you wish.

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> 
Linda Cosgrove, Ph.D., Editor,         Evaluation Staff Traffic     Safety Programs(202) 366-2759