A multiuser automatic vehicle monitoring system being developed for deployment in Los Angeles is discussed. In addition to the basic signpost technique to be used along transit routes and in the central business district, relatively inexpensive long-range navigation (loran) receivers will be used in a few vehicles to provide general location information over the entire 1000-sq km (400 sq mi) Los Angeles Basin. Three techniques to convert loran time differences (TD) of arrival information to latitude and longitude were evaluated for accuracy, computation time, and memory requirements. The three methods are an empirical regression technique that uses best-fit equations to fit measured TDs to locations, a theoretical technique that uses a geometric earth model and a radio-wave-propagation model to determine location based on travel times from the known transmitters, and a combination technique that computes the position theoretically and then provides an empirical correction. All techniques gave approximately the same accuracy. It is possible that subdivision of the larger area into sectors could improve the overall accuracy to that of the central area, but not enough data were available to test this. It appears that TD grid warpages in the Los Angeles area are large enough and not sufficiently regular to be compensated for by standard techniques. (Author)

Media Info

  • Media Type: Print
  • Features: Figures; Maps; References; Tables;
  • Pagination: pp 29-34
  • Monograph Title: Urban Systems and Traffic Evaluations
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00334534
  • Record Type: Publication
  • ISBN: 0309031141
  • Files: TRIS, TRB
  • Created Date: Oct 28 1981 12:00AM