Bicyclists’ Inclination and Ability to Search behind before Turning Left

Details

• Creators:
  Casey, S. M. (Steven Michael), 1952- ; Cross, Kenneth D. ; Leaf, W. A. ; Blomberg, Richard D.
• Corporate Creators:
  Dunlap and Associates, inc.
• Corporate Contributors:
  United States. National Highway Traffic Safety Administration ; Anacapa Sciences, inc.
• Subject/TRT Terms:
  Accident Causes Bicycles Cyclists Field Studies Left Turns
• Publication/ Report Number:
  DOT-HS-805-893
• DOI:
  https://doi.org/10.21949/1525006
• Resource Type:
  Research Paper
• Geographical Coverage:
  United States
• Edition:
  Interim report
• Corporate Publisher:
  United States. National Highway Traffic Safety Administration
• Abstract:
  Author's abstract: Research (Cross and Fisher, 1977) has identified a relatively high incidence (8.4%) bicycle/motor-vehicle accident type in which a bicyclist initiates a left-hand turn without searching to the rear or signaling and is struck by an overtaking motor vehicle. In order to consider countermeasures to this accident type, it was necessary to understand the frequency with which bicyclists actually search behind before turning left, and to determine the ability of bicyclists to maintain lateral stability when looking behind. Hence, two separate studies were conducted. The first, a field-observation study, was performed to assess the frequency with which bicyclists search behind before initiating a left-hand turn. Field investigators observed and recorded data on 1,012 left-hand turns by bicyclists. The relationships between search failure and selected environmental, operator and vehicular factors are described. The percentages of search failures were found to range from 23% at locations with high traffic density to 79% at locations with the lowest traffic density. The second experiment measured the magnitude of the inadvertent lateral deviations that accompany a rearward search as a function of the bicyclist's age and riding experience. Of major interest was the magnitude of the largest deviation from a straight line path ("maximum error"). It was found that maximum error was greater for trials involving rearward search than for those which did not. However, the absolute error was relatively small. The 99th centile error was only 20 inches. Error was lower for more experienced bicycle riders but was unrelated to age. The totality of results indicate that it would likely not be counterproductive to promote universal rearward searches in bicycle safety education or training programs.
• Format:
  PDF
• Funding:
  DOT-HS-7-01726
• Collection(s):
  NHTSA - Behavioral Safety Research
• Main Document Checksum:
  urn:sha256:0c1bdc266cf1ed81b54834d4761b7ec01700a0a971356d02fcbbb8c4075bca91
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/1227/dot_1227_DS1.pdf
• File Type:
  [PDF - 5.85 MB ]