The purpose of this study, funded by the Utah Department of Transportation, was to produce a freeway congestion index (FCI). The data required for the FCI can be developed with or without the benefit of automated traffic surveillance or data collection systems. A 9.7-km (6-mi) segment of I-15 in the Salt Lake City metropolitan area was used to test the viability of the FCI. The FCI reflects both the extent (length) and duration of congestion on a given freeway segment and can be used to compare congestion levels on different freeway segments or subsystems, and to compare congestion levels on freeway systems of differing sizes. It can also be used to compare changes in the level of congestion as they occur over time (from year to year or between different seasons of the year). Speed was used as the indicator of congestion onset, with acquisition of the needed data for calculation of the FCI being done using an instrumented moving vehicle. It was also found that measurements taken in a single lane can be used to accurately determine the FCI for all lanes of a six-lane freeway.


  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 21-29
  • Monograph Title: Traffic operations, traffic signal systems, and freeway operations 1995
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00714895
  • Record Type: Publication
  • Files: TRIS, TRB, ATRI
  • Created Date: Dec 13 1995 12:00AM