6.1.4.1 Relative Comparison of CMFs

The relative comparison of CMFs method is used to compare the potential safety impacts of alternatives by comparing the CMF values for each of the proposed alternatives or countermeasures. Comparing CMFs involves verifying that the comparisons are of identical crash types and other details. This method is typically used when historical crash data is not available. This method is the simplest method to apply and involves careful selection of CMFs. The relative comparison of CMFs method is most suitable for the initial screening of viable countermeasures before performing a more detailed analysis.
The basic analysis steps when performing a relative comparison of CMFs analysis are as follows:
  • Determine the safety study area;
  • Identify the existing conditions and proposed countermeasure(s) or alternative(s);
  • Determine and document the appropriate CMF(s) for each countermeasure or alternative; and
  • Use the results to determine next steps for additional analysis, if needed
provides an
example
of how the relative comparison of CMFs analysis method could be applied. This example considers various alternatives for pedestrian facility modifications using CMFs located on the CMF Clearinghouse website. A general overview of CMFs is provided in
Chapter 5, Section 5.4
.