EFFECTIVENESS OF GREEN-EXTENSION SYSTEMS AT HIGH-SPEED INTERSECTIONS
The purpose of this study was to determine the effectiveness of green-extension systems (GES) for reducing the dilemma-zone problem associated with the amber phase of traffic signals at high-speed intersections. Reactions of 2,100 drivers were noted during the amber phase at none intersections, and the dilemma-zone distances with respect to the stop bar were determined. Before-and-after studies made at three green-extension sites showed a 54-percent reduction in total accidents and a 75-percent reduction in rear-end accidents after GES installation. Accident severity was unaffected. Conflict, volume, delay, and speed data were taken before and after GES installation at two sites. A 62 percent reduction in yellow-phase conflicts was noted after green extension was provided, and conflict rates decreased significantly at both sites. No significant change was found in vehicle delay due to green extension. Expected present-worth benefits due to GES installations were found to range from $29,000 to $420,000, depending on the history of rear-end accidents. Benefit-cost ratios ranged from 6 to 70. /Author/
- Record URL:
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Corporate Authors:
Kentucky Department of Transportation
Bureau of Highways
Frankfort, KY United States 40601 -
Authors:
- Zegeer, C V
- Publication Date: 1977-5
Media Info
- Features: Appendices; Figures; References; Tables;
- Pagination: 31 p.
Subject/Index Terms
- TRT Terms: Amber; Before and after studies; Drivers; Green interval (Traffic signal cycle); High speed ground transportation; High speed vehicles; Intersections; Reaction time; Rear end crashes; Speed; Traffic conflicts; Traffic crashes; Traffic delays; Traffic signals; Traffic volume
- Uncontrolled Terms: Driver reaction
- Subject Areas: Highways; Railroads; Safety and Human Factors;
Filing Info
- Accession Number: 00164086
- Record Type: Publication
- Source Agency: National Safety Council Safety Research Info Serv
- Report/Paper Numbers: Research Rept. 472 Final Rpt.
- Contract Numbers: KYP-75-69
- Files: TRIS, STATEDOT
- Created Date: Nov 9 1977 12:00AM