CMF Update, Summer 2011

The Summer 2011 edition of CMF Update is the fourth edition of the Crash Modification Factors Clearinghouse e-newsletter. To subscribe to our newsletter, please visit

To view archived issues, please visit

New CMFs added to the Clearinghouse!

Over 540 crash modification factors (CMFs) have been added to the Clearinghouse since March 2011. Collectively, the clearinghouse now contains 3,250 CMFs for over 770 countermeasures.

Featured CMFs

The CMF Clearinghouse continually updates the online resource with new CMFs. Each edition CMF Update will feature a few CMFs from the latest group that was uploaded to the Clearinghouse. These CMFs are chosen to give a flavor of the types of CMFs that were most recently added to the Clearinghouse. Below is the list of this edition's featured CMFs.

Convert two-way to all-way stop control
CMF: 0.319
CRF: 68.1
Star Quality Rating: 4 stars

Install raised median
CMF: 0.75
CRF: 25
Star Quality Rating: 4 stars

Install wider edgelines (4 in to 6 in)
CMF: 0.9
CRF: 10
Star Quality Rating: 4 stars

Installation of cable barriers in freeway medians
CMF: 0.56
CRF: 44
Star Quality Rating: 3 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: Highway Safety Manual Part C Quick Reference Guide

Before using CMFs, many transportation engineers may want to determine the estimated expected average crash frequency for a road segment or intersection. Part C of the AASHTO Highway Safety Manual contains crash prediction models for various road classes. The TRB Highway Safety Performance Committee (ANB25) has developed a quick reference guide for the predictive models contained in Part C. Their intention in developing this guide was to support training and implementation of the HSM. The committee states that the reference guide is provided as is with no warranties and can be downloaded using the following link:


Featured FAQ: How can I download CMFs from the Clearinghouse?

If you would rather work with CMFs in a spreadsheet rather than using the online interface, the CMF Clearinghouse provides an option for downloading CMFs to your local computer. For example, some state agencies maintain an internal list of CMFs that they use for in-house analyses. They use the spreadsheet output from the Clearinghouse to periodically download CMFs and update their internal list. To facilitate this process, the spreadsheet output includes a date field for each CMF that indicates when the CMF was added to the Clearinghouse.

Once you have performed a search using the Quick Search or Advanced Search, you can download the search results in spreadsheet form. Simply click the link at the bottom of the page for "Export all results to Excel". This will give you an Excel output of the star rated CMFs. If there were also CMFs returned for your search that do not have star ratings, and you wish to download those in spreadsheet format, click the link for "view additional results" and then use the Excel export link at the bottom of that page to download the non star rated CMFs.

If you wish to download all the CMFs in the Clearinghouse, do an Advanced Search and leave the search term box blank. This will return the entirety of the CMF Clearinghouse database. Again, if you wish to download these CMFs in spreadsheet form, you will need to download the star rated and non star rated CMFs separately.

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 HSIP.

Submit your Ideas for CMF Research Needs to the Clearinghouse

What CMF(s) are needed in your line of work but are not presented in the CMF Clearinghouse? The CMF Clearinghouse now has a feature on the website for submitting ideas or needs you have for CMFs that are not presented in the CMF Clearinghouse. Please use the provided form at to submit your CMF need. If there are published studies on that topic, the Clearinghouse team will endeavor to target those studies for review and inclusion in the Clearinghouse. If there are no published studies on that countermeasure, the idea will be retained as a future research need.