CMF Update, Summer 2013

The summer 2013 edition of CMF Update is the seventh edition of the Crash Modification Factors Clearinghouse e-newsletter. To subscribe, please visit

To view archived issues, please visit

Clearinghouse launches improved search tool

Searching for a CMF is now more intuitive, thanks to an update to the CMF Clearinghouse website this summer. The new, improved search tool simplifies searching and assists users in sorting results to find the most appropriate CMF. Now all searches begin on the website’s homepage, then users can filter results using the tool on the left side of the results page to eliminate CMFs that do not apply to their needs. For example, a user looking for CMFs for urban areas would expand the “area type” pull down and filter to display only urban CMFs. In addition to area type, the following filters are provided: star quality rating, crash type, crash severity, roadway type, intersection type, intersection geometry, traffic control and whether the CMF appears in the Highway Safety Manual.

Usability tests

A series of usability tests conducted in June 2013 helped identify any issues with the new search before its launch. At the conclusion of these tests, several adjustments were made before the new search went “live” on Thank you to the volunteers who participated in testing. Your feedback helped provide a stronger, more helpful search tool for everyone. If you were not part of the usability tests and have suggestions or other feedback about the Clearinghouse, we’d love to hear from you. Please contact Karen Scurry at

Featured CMFs

The CMF Clearinghouse is continually updated with new CMFs. Below are CMFs recently added to the Clearinghouse database.

Replace night-time flash with steady operation
Crash Modification Factor (CMF) Value: 0.52

Star Quality Rating: 4 stars

Convert a 2 ft. turf shoulder to a 10 ft. paved shoulder (bituminous base)
Crash Modification Factor (CMF) Value: 0.84

Star Quality Rating: 3 stars

Featured resource: CMFs in Practice

This Federal Highway Administration resource illustrates how CMFs support a number of safety-related activities in the project development process. The series includes five separate guides that identify opportunities to consider and quantify safety in specific activities, including roadway safety management processes, road safety audits, design decisions and exceptions, development and analysis of alternatives, and value engineering. The purpose of the CMFs in Practice series is to illustrate the value of CMFs in these five activities and demonstrate practical application of CMFs. For more information about CMFs in Practice, visit:

Featured FAQ: How are CMFs added to the Clearinghouse and what is the process for review?

CMFs for the Clearinghouse are obtained either through 1) a regular examination of presented or published material or 2) studies that are submitted by Clearinghouse users through the website. All studies that are determined to be eligible for the Clearinghouse (i.e., studies that produce one or more CMFs) are submitted to a review process. Presented and published studies considered for the CMF Clearinghouse will be taken from the following sources:

  • Transportation Research Board Annual Meeting Compendium of Papers
  • American Society of Civil Engineers Journal
  • Institute of Transportation Engineers Journal
  • Accident Analysis and Prevention
  • Journal of Safety Research
  • Broad search of existing literature using the Transportation Research Information Services (TRIS)

The review process evaluates each study according to its study design, sample size, standard error, potential bias and data source and gives a rating of excellent, fair or poor to each category. These ratings correspond to point values in a scoring system that is used to determine the star quality rating.

Submit a study

The CMF Clearinghouse welcomes CMF study submissions to be included in its searchable database. Please use the provided form at to submit your study. Be sure to search before submitting a new CMF as it may already be listed. You may either submit a link to a resource already existing on the web (preferred) or upload your own file. Submissions might include published research studies that are not presented in the Clearinghouse, or state-specific CMFs that were developed as part of the Highway Safety Improvement Program.