Analysis of VASCAR

Details

• Creators:
  Howe, J.G.
• Subject/TRT Terms:
  Accuracy Law Enforcement Manuals Speed Calculation Speed Limits Traffic Speed Measurement VASCAR-plus
• Publication/ Report Number:
  DOT-HS-807-748 ; VRTC-70-167
• Resource Type:
  Manual
• Geographical Coverage:
  United States
• Corporate Publisher:
  United States. Department of Transportation. National Highway Traffic Safety Administration
• Abstract:
  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 +_ 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 +_ 1%, but that a + 2 mph upper 90th percentile tolerance limit (95% of the speed errors are
  
  less than + 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).
  
  
• Format:
  PDF
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:40fca1ac9e14e9686a372371149e4519fad8c909e7d36699cf38cbdf0dd273b4
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/13773/dot_13773_DS1.pdf
• File Type:
  [PDF - 9.58 MB ]