EVALUATION OF DETECTOR PLACEMENT FOR HIGH-SPEED APPROACHES TO SIGNALIZED INTERSECTIONS

The primary objective of this research was to validate the new Texas Department of Transportation (TxDOT) procedures for loop detector placement on high-speed approaches to signalized intersections. The study approach involved conducting a field study at selected sites to compare the proposed new loop configuration to the existing configuration. The data analysis included investigating approach speeds to the intersection, driver actions in response to a yellow indication, and vehicle location at the onset of yellow. Results from the field study revealed that the new loop configuration is as good as, and in some cases better than, the old loop configuration. Because the new loop configuration can detect vehicles further upstream from the intersection (at the beginning of the dilemma zone), it results in fewer vehicles being caught in the dilemma zone at the onset of yellow. The new loop configuration resulted in fewer vehicles running the red light, a major cause of accidents. Also, because the new loop configuration typically resulted in more vehicles using the yellow light instead of stopping, fewer rear-end accidents may result.

• Supplemental Notes:
  • Research study title: Evaluation of TxDOT Detector Placement for High-Speed Approaches to Signalized Intersections.
• Corporate Authors:

  Texas Transportation Institute

  Texas A&M University System, 1600 E Lamar Boulevard
  Arlington, TX  United States  76011

  Texas Department of Transportation

  Research and Technology Transfer Office, P.O. Box 5051
  Austin, TX  United States  78763-5051
• Authors:
  • Middleton, D
  • Nowlin, R L
  • Shafer, M
  • Parham, A H
  • Jasek, D
• Publication Date: 1997-9

Language

• English

Media Info

• Features: Appendices; Figures; Photos; References; Tables;
• Pagination: 114 p.

Subject/Index Terms

• TRT Terms: Approach; Approach lanes; Clearance interval (Traffic signal cycle); Drivers; Field studies; High speed ground transportation; High speed vehicles; Intersections; Location; Loop detectors; Reaction time; Signalized intersections; Speed; Yellow interval (Traffic signal cycle)
• Uncontrolled Terms: Driver reaction
• Old TRIS Terms: Approach speed; Intersection approach; Placement
• Subject Areas: Highways; Operations and Traffic Management; Railroads; I73: Traffic Control;

Filing Info

• Accession Number: 00748800
• Record Type: Publication
• Report/Paper Numbers: TX-98/3977-1,, Res Rept 3977-1,, TTI: 7-3977, Interim Rept
• Contract Numbers: Study 7-3977
• Files: TRIS, ATRI, STATEDOT
• Created Date: May 22 1998 12:00AM