ANALYSIS OF VASCAR. FINAL REPORT

This study is part of an effort by the National Highway Traffic Safety Administration (NHTSA) to determine the accuracy of the VASCAR-plus speed measurement device. VASCAR-plus is used extensively for speed law enforcement by state and local police. VASCAR-plus calculates average speed using the basic formula: Speed = Distance/Time. The VASCAR-plus manual claims an overall speed measurement accuracy of plus or minus 1%. This accuracy was recently challenged. This study determined the accuracy of VASCAR-plus time, distance, and speed measurements. Two VASCAR-plus units were electronically tripped (no human operator) to determine the timing accuracy. Six VASCAR certified officers participated in a study to determine VASCAR-plus distance measurement accuracy. Eight VASCAR certified officers participated in a series of studies to determine VASCAR-plus speed measurement accuracy. The results of these studies show that VASCAR-plus does not have an overall speed measurement accuracy of plus or minus 1%, but that a plus 2 mph upper 90th percentile tolerance limit (95% of the speed errors are less than plus 2 mph) is achievable when the speed measurement is 4 seconds in duration for stationary methods (angular and parking), and is 5 seconds in duration for moving methods (following and approaching from the rear).

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• Record URL:
  https://rosap.ntl.bts.gov/view/dot/13773
• Corporate Authors:

  National Highway Traffic Safety Administration

  Vehicle Research and Test Center, P.O. Box 37
  East Liberty, OH  United States  43319
• Authors:
  • Howe, J G
• Publication Date: 1991-5

Media Info

• Features: Appendices; Figures; Tables;
• Pagination: v.p.

Subject/Index Terms

• TRT Terms: Accuracy; Measuring instruments; Speed limits; Speed measurement; Traffic law enforcement
• Subject Areas: Highways; Safety and Human Factors; I10: Economics and Administration;

Filing Info

• Accession Number: 00622661
• Record Type: Publication
• Source Agency: National Highway Traffic Safety Administration
• Report/Paper Numbers: VRTC-70-167,, HS-807 748
• Files: HSL, NTL, TRIS, USDOT
• Created Date: Jun 30 2000 12:00AM