Introduction to the CMF Clearinghouse

What is the purpose of the CMF Clearinghouse?

The CMF Clearinghouse serves three important roles for the transportation safety field.

1. Provides CMF Data
The CMF Clearinghouse is a comprehensive and searchable database of published CMFs. It contains all CMFs published in 2010 or after as well as many CMFs published before that date, such as those compiled in the first edition of the AASHTO Highway Safety Manual and the FHWA Desktop Reference for Crash Reduction Factors. It provides information on all available CMFs, such as the CMF value and all published details about the CMF; citations and related information about the study that produced each CMF; and a star rating that provides an indication of the quality of each CMF. It is regularly updated to include newly published CMFs.

2. Educates CMF Users
The CMF Clearinghouse provides guidance material to instruct users about the appropriate use of CMFs. Through a series of Frequently Asked Questions, the Clearinghouse provides answers to many important CMF-related questions posed by city and state transportation engineers, planners, and researchers. The CMF Clearinghouse also sponsors an annual webinar to provide guidance on appropriate use of CMFs and best practices from state agencies. In addition to the guidance provided from the Clearinghouse, the website also provides links to many external resources in categories such as “How to Develop and Use CMFs”, “Cost-Benefit Analyses”, and “Training”.

3. Facilitates CMF Research
Researchers often use CMF Clearinghouse data to determine if there are any CMFs existing on a potential research topic and where research gaps are present. To direct future research, the CMF Most Wanted List is provided to show researchers and funding agencies the countermeasures and topics that are high priority to Clearinghouse users but not present in the Clearinghouse data. The CMF Clearinghouse also provides safety researchers with a mechanism to submit CMFs for inclusion in the Clearinghouse.

What kind of CMFs does the CMF Clearinghouse include?

It is important to understand what the Clearinghouse does and does not include. The CMF Clearinghouse presents CMFs from studies that meet the following criteria:

Where DO CMFS come from?

The CMF Clearinghouse team, which consists of engineers with many years of safety research experience, identifies eligible CMFs through a regular review process of published reports and professional journals. The review cycle is conducted four times per year and consists of reviewing papers from the following sources:

Quarter 1

  • Transportation Research Board Annual Meeting Compendium of Papers (past meeting)
  • User-submitted studies (past 3 months)

Quarter 2

  • American Society of Civil Engineers Journal of Transportation Engineering (past 6 months)
  • Institute of Transportation Engineers Journal (past 6 months)
  • Accident Analysis and Prevention (past 6 months)
  • Journal of Safety Research (past 6 months)
  • User-submitted studies (past 3 months)

Quarter 3

  • Searches on the Transport Research International Documentation (TRID, formerly TRIS)
  • User-submitted studies (past 3 months)

Quarter 4

  • American Society of Civil Engineers Journal of Transportation Engineering (past 6 months)
  • Institute of Transportation Engineers Journal (past 6 months)
  • Accident Analysis and Prevention (past 6 months)
  • Journal of Safety Research (past 6 months)
  • User-submitted studies (past 3 months)

The process for each review cycle is:

Prior to its launch in 2010 and the start of a regular review cycle, the Clearinghouse was initially populated with CMFs from two major resources, the first edition of the AASHTO Highway Safety Manual (HSM) and the FHWA Desktop Reference for Crash Reduction Factors. The Clearinghouse provides a page of information on the relationship to the HSM, including the scopes of the two resources and details on how star ratings were applied to CMFs from the HSM.

Next Chapter: Searching for CMFs on the CMF Clearinghouse -->

The information contained in the Crash Modification Factors (CMF) Clearinghouse is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in the CMF Clearinghouse. The information contained in the CMF Clearinghouse does not constitute a standard, specification, or regulation, nor is it a substitute for sound engineering judgment.