title: Case-control and cross-sectional methods for estimating crash modification factors: comparisons from roadway lighting and lane and shoulder width safety effect studies.
abstract: OBJECTIVE
  While observational before-after studies are considered the industry standard for developing crash modification factors (CMFs), there are practical limitations that may preclude their use in highway safety analysis. There is a need to explore alternative methods for estimating CMFs.
  
  
  METHODS
  This paper employs case-control and cross-sectional analyses to estimate CMFs for fixed roadway lighting and the allocation of lane and shoulder widths.
  
  
  RESULTS
  Based on the case-control method, the CMF for intersection lighting is 0.886, while the cross-sectional study indicates a CMF of 0.881. The CMFs developed for lane and shoulder widths are also similar when comparing the two methods.
  
  
  CONCLUSIONS
  This paper suggests that case-control and cross-sectional studies produce consistent results if care is taken in the study design and model development.
  
  
  CONCLUSIONS
  Case-control and cross-sectional studies may provide a viable alternative to estimate CMFs when a before-after study is impractical due to data restrictions.
authors.affiliation: Vanasse Hangen Brustlin, Inc. 333 Fayetteville St, Suite 1450, Raleigh, NC 27601, USA. fgross@vhb.com
authors.forename: Frank
authors.initials: F
authors.lastname: Gross
authors.forename: Eric T
authors.initials: ET
authors.lastname: Donnell
mesh_terms: D000063:Accidents, Traffic / Q000517:prevention & control*; D000465:Algorithms; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D004779:Environment Design; D006801:Humans; D008029:Lighting; D012449:Safety; D014481:United States