A NEW METHOD FOR ACCIDENT ANALYSIS

The evaluation of the effectiveness of safety improvements using accident data has been a difficult task complicated by anomalies such as the regression-to-the-mean phenomenon, lack of control through traditional experimental design considerations, and insufficient sample sizes (e.g., accident frequencies and/or number of experimental units - sites). Statistical methods have been proposed to remove subjective bias which may confound conclusions in such cases. This study, funded by the Federal Highway Administration, examines various statistical procedures under a variety of applications to determine which procedures are most effective under what circumstances. Examples range from the simplest before/after design with no comparison group to multiple observations in time on a before/after with comparison group study. These procedures were applied to situations with few sites and high accident frequencies (such as changing posted speed on multilane high volume highway sections) as well as situations with many sites but low accident frequencies (such as signalization at intersections). Both actual and simulated data is used in these comparison. The sophistication of the statistical methods range from the most elementary procedures currently in use to more recently proposed sophisticated methods of Empirical Bayes estimation and time series analyses. Recommendations are made regarding which procedures are optimal for specific study designs. Also, design considerations are proposed which may alleviate problems and simplify the statistical analysis apriori to data collection. For the covering abstract of the conference see IRRD 832707. (A)

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/03476030
• Corporate Authors:

  Swedish National Road and Transport Research Institute (VTI)

  Linköping,   Sweden  SE-581 95
• Authors:
  • Pendleton, O
  • Morris, C
• Publication Date: 1990

Language

• English

Media Info

• Pagination: p. 189-210
• Serial:
  • VTI Rapport
  • Issue Number: 351A
  • Publisher: Swedish National Road and Transport Research Institute (VTI)
  • ISSN: 0347-6030

Subject/Index Terms

• TRT Terms: Before and after studies; Conferences; Crash rates; Distributions (Statistics); Evaluation and assessment; Mathematical analysis; Methodology; Prevention; Safety; Statistics
• Identifier Terms: Strategic Highway Research Program
• Geographic Terms: Germany
• ITRD Terms: 1661: Accident prevention; 1612: Accident rate; 6471: Analysis (math); 9148: Before and after study; 8525: Conference; 6572: Distribution (stat); 9020: Evaluation (assessment); 8125: Germany; 9102: Method; 9122: SHRP; 6555: Statistics
• Subject Areas: Data and Information Technology; Safety and Human Factors; Security and Emergencies;

Filing Info

• Accession Number: 00607052
• Record Type: Publication
• Source Agency: Transport and Road Research Laboratory (TRRL)
• Files: ITRD, TRIS, ATRI
• Created Date: Mar 31 1991 12:00AM