This report describes a series of experiments that were conducted to examine the effectiveness of four-way flashers. Both the disabled vehicle situation and the slow-moving vehicle situation were examined at two- and four-lane locations under both daylight and nighttime conditions. The disabled vehicle tests involved parking a test vehicle (either a car or a tractor-trailer) at the side of the road and monitoring the behavior of drivers. The slow-moving vehicle tests involved introducing a staged slow-moving vehicle (either a car or a tractor-trailer) into the traffic stream and observing the overtaking vehicles. At the disabled vehicle, red and amber four-way flashers as well as flares, reflectorized triangles, headlights, and other situational factors were evaluated. For the slow-moving vehicle tests, the effects of red and amber flashers as well as a 30 and 40 mph (48.3 and 64.4 kph) slow-moving vehicle were examined. For both the disabled and the slow-moving vehicle situations, it was found that four-way flashers are effective at reducing the inherent danger. In the disabled situation, it was found that approaching motorists slow down sooner and slow down more when flashers are displayed. In the slow-moving situation, it was found that drivers of overtaking vehicles approach more cautiously and pass more carefully. In both situations flashers increase the awareness of the drivers of overtaking vehicles. (FHWA)

  • Corporate Authors:

    Biotechnology, Incorporated

    3027 Rosemary Lane
    Falls Church, VA  United States  22042

    Federal Highway Administration

    Traffic Systems Division, 1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Knoblauch, R L
    • Tobey, H N
  • Publication Date: 1980-9

Media Info

  • Pagination: 21 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00335994
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-RD-80-101 Final Rpt., FCP 31A1-774
  • Contract Numbers: DOT-FH-11-9385
  • Files: TRIS, ATRI, USDOT
  • Created Date: Oct 28 1981 12:00AM