How are CMFs from the Highway Safety Manual (HSM) related to CMFs published in the CMF Clearinghouse?

• A. The Highway Safety Manual contains a limited number of high-quality CMFs; these CMFs are published, along with many others, in the CMF Clearinghouse.
• B. CMFs published in the CMF Clearinghouse are not associated with the HSM.
• C. The Highway Safety Manual provides a complete CMF catalog; Clearinghouse is redundant.
• D. CMFs are identical across both sources and require no clearinghouse.

Answer: (A)

CMFs in the Highway Safety Manual are a vetted, limited set of high-quality factors used to estimate safety effects. These same CMFs are published in the CMF Clearinghouse, which is a central repository that collects CMFs from the HSM and from other sources. This setup lets practitioners access a broader, multi-source collection of CMFs while still benefiting from the HSM’s recognized, high-quality entries. The Clearinghouse is not redundant or unrelated to the HSM; it expands availability and comparison options, while the HSM provides a vetted subset that anchors practice.