This evaluation was undertaken to determine the effectiveness of the RED SIGNAL AHEAD (RSA) sign and develop guidelines for its use. The RSA sign is intended to increase motorist awareness of a traffic signal when this dynamic device is placed in advance of an unexpected signalized intersection. In brief, this study concludes that the RSA sign has the potential to be an effective device in reducing right angle accidents at signalized intersections where certain geometric and traffic conditions exist. The results of this study followed an investigation into accident and non-accident measures of effectiveness (MOE's). Non-accident MOE's included approach speeds, through on yellow/red interval movements and initial brake application locations. The MOE's were examined for a composite of all locations and by variations in certain key elements. Those elements considered to be significant were approach geometry, sight distance, and traffic volume. Two analyses were performed with the accident data. A three year Before/After (B/A) accident study and a one year B/A accident study with a "control" group. Both accident analyses concur that a significant reduction in right angle accidents followed the installation of the RSA sign. The analyses were not conclusive regarding effects on rear end, total and truck accidents. There was some indication that rear end accidents tend to increase. For total accidents as well as truck accidents the two analyses disagree on the RSA sign's effectiveness. The non-accident MOE's revealed that the RSA sign influences approach speeds, but does not appear to affect through on yellow/red interval movements. Also, the initial brake applications appeared to be a function of the geometric approach to the intersection. These same non-accident MOE's and the above accident MOE's were used to compare the RSA sign with the SYMBOL SIGNAL AHEAD/YELLOW (continuously) Flashing Beacons (W3-3/YFB) device.

Media Info

  • Features: Appendices; Figures; Tables;
  • Pagination: 108 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00452242
  • Record Type: Publication
  • Source Agency: National Highway Traffic Safety Administration
  • Report/Paper Numbers: FHWA/MD-83/06 Final Rpt., HS-038 678
  • Contract Numbers: AW083-264-046
  • Created Date: Jan 31 1986 12:00AM