ITE Journal - May 2020 - 45

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TOOL

Developing, Using, and Improving Tables
Showing the Safest Feasible Intersection Design

I

By Joseph E. Hummer, P.E., Ph.D. (M)
n recent years, the Federal Highway Administration (FHWA) and the states have
invested millions of dollars in research on the safety performance of different measures
at intersections. Much of this research has been cataloged in an easy-to-use website
called the "Crash Modification Factors Clearinghouse"1 maintained by the FHWA. The

Clearinghouse contains thousands of crash modification factors (CMFs), which are defined as
the ratio of the estimated crash frequency after an intervention to the crash frequency before the
intervention. A CMF below one thus means the intervention helped. Happily, researchers have
rated the quality of each CMF in the Clearinghouse, on a scale of zero stars (poor or unknown
quality, result should not be trusted) to five stars (excellent quality, trustworthy result), so that
consumers of the information do not have to make that judgment. The library of CMFs, each
with a quality rating, is a tremendous resource.
w w w .i t e.or g

May 2020

45

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ITE Journal - May 2020

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