New VASCAR-plus timing mechanism test results

Details

• Creators:
  Howe, J.G.
• Subject/TRT Terms:
  • Traffic speed measurement
  • Speed control
  • Traffic law enforcement
  • Speeding
  • VASCAR-plus
  • speed measuring device
  • time-distance speed measurement
  • timing mechanism
• Publication/ Report Number:
  DOT HS 807 981
• Resource Type:
  Research Paper
• Geographical Coverage:
  United States
• Corporate Publisher:
  United States. Department of Transportation. National Highway Traffic Safety Administration
• Abstract:
  In a previous study (Analysis of VASCAR, DOT HS 807-748, May 1993), it was found that the VASCAR-plus timing mechanism was biased against the speed limit violator. The VASCAR speed reading was higher than the actual speed. At that time, it was suggested by the Law Enforcement ; Community that the timing mechanism be modified so that it would be in favor of the violator (VASCAR speed less than actual speed). Since that time, the manufacturer of VASCAR-plus has changed the timing device. The study described in this report was conducted to determine the accuracy of the new timing mechanism. To determine actual timing errors for the VASCAR-plus with the new timing method, a series of ; bench tests were performed similar to those described above. Both a Nicolet oscilloscope and a VASCAR-plus unit were simultaneously triggered using two trip switches. The oscilloscope sample rate was set to 1 msec. Two VASCAR-plus units were tested. A total of 50 tests was performed on each unit. With the new timing data collection method, when the time switch is turned off the VASCAR computer collects data for 2 more 36 msec time steps. The timing errors for this method should range from 36 to 72 msec. Since these timing errors are positive, they would be biased in favor of the violator.
• Format:
  PDF
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/13775/dot_13775_DS1.pdf
• File Type:
  [PDF - 623.69 KB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:98991053cdda6ce77b8e124b9b6ce5713f762c78c4e3fc56b65c55e04e2efa91