Search Help

How does the CMF search work?

The CMF Clearinghouse search function allows you to search the database for CMFs related to your topic of interest. On the homepage, you enter your search term (e.g., rumble strips) in the text box and select an option in the pull-down menu as to what field you want to search. If you are new to the Clearinghouse, you may want to leave it on the default option of “Countermeasure Name” to get a more focused set of results. Here what the other options mean:

Once you click “Search CMFs”, you will be taken to the page of search results. The search results page will show you how many CMFs matched your search term and you will be provided with filters on the left side of the screen to narrow down the results to fit your particular scenario.

My search resulted in too few or no CMFs. How can I find what I'm looking for?

There may be several reasons that you are getting too few or no CMFs in your search results. Here are some things to try:

If you have tried these options and are still not finding any results, it is likely that the CMF Clearinghouse does not contain any CMFs for that search term. This reflects the fact that the safety research field still has many topics and countermeasures in need of good quality, crash-based research. For a list of such topics, see the CMF Most Wanted List (

My search produced too many results. How can I narrow my search results?

If you're overwhelmed by a huge list of results, try the following things to narrow your search:

What if I don't know exactly what countermeasure or CMF I'm looking for, and I just want to see what the Clearinghouse contains?

The Clearinghouse search tool is designed so that a blank search (i.e., no search term) will return all CMFs. You will find that the expandable search results will assist you in getting an overview. You can expand a category to view all the countermeasures covered in that category, and then expand any particular countermeasure to view all the CMFs that address that countermeasure.

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.