CMF Update, Fall 2010

The Fall 2010 edition of CMF Update is the second edition of the Crash Modification Factors Clearinghouse e-newsletter. To subscribe to our newsletter, please visit

New Format for Search Results

The CMF Clearinghouse has implemented a new design for search results!

Now Clearinghouse users can expand and collapse individual categories and countermeasures to navigate through the CMF search results page. Since some searches can result in hundreds of matches from the CMF database, this new format will allow users to better see an overview of the results that are returned for their search.

New Search Results layout

Featured CMFs

Each edition CMF Update will feature CMFs of interest. The CMF Clearinghouse continually updates the online resource with new CMFs. Below is the list of this edition's featured CMFs.

Install centerline and/or shoulder rumble strips
CMF: 0.82
CRF: 18
Star Quality Rating: 4 stars

Install HAWK pedestrian crossing beacon
CMF: 0.39
CRF: 60
Star Quality Rating: 4 stars

The CMF Clearinghouse will be updated on a regular basis to add recently developed and documented CMFs. New CMFs will be identified via a periodic review of published literature. In addition, the CMF Clearinghouse provides a mechanism for transportation professionals to submit their own CMFs to be considered for inclusion.

Featured Resource: SafetyAnalyst

SafetyAnalyst Website

SafetyAnalyst provides a set of software tools used by state and local highway agencies for highway safety management. SafetyAnalyst can be used by highway agencies to improve their programming of site-specific highway safety improvements. These tools incorporate state-of-the-art safety management approaches into computerized analytical tools for guiding the decision-making process to identify safety improvement needs and develop a system-wide program of site-specific improvement projects. SafetyAnalyst has a strong basis in cost-effectiveness analysis; thus, SafetyAnalyst has an important role in ensuring that highway agencies get the greatest possible safety benefit from each dollar spent in the name of safety. CMFs from the CMF Clearinghouse can be used in the Economic Appraisal Tool to aid in estimating the benefit of countermeasures.

SafetyAnalyst was developed as a cooperative effort by FHWA and participating state and local agencies. AASHTO manages distribution, technical support, maintenance, and enhancement of SafetyAnalyst as a licensed AASHTOWare product. For more information, please visit

Featured FAQ: How can I apply multiple CMFs?

If multiple countermeasures are implemented at one location, then common practice is to multiply the CMFs to estimate the combined effect of the countermeasures. In fact, there is limited research documenting the combined effect of multiple countermeasures. Although implementing several countermeasures might be more effective than just one, it is unlikely the full effect of each countermeasure would be realized when they are implemented concurrently, particularly if the countermeasures are targeting the same crash type. Therefore, unless the countermeasures act completely independently and target unique crash types, multiplying several CMFs is likely to overestimate the combined effect. The likelihood of overestimation increases with the number of CMFs that are multiplied. Therefore, much caution and engineering judgment should be exercised especially when estimating the combined effect of more than 3 countermeasures at a given location.

For more answers to frequently asked questions, please visit

Submit your CMFs to the Clearinghouse

The CMF Clearinghouse welcomes CMF study submissions to be included in its searchable database. Please use the provided form at to submit your study. Prior to submitting, please be sure to search before submitting a new CRF 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 (HSIP).