SPR 19-578: Crash Modification Factor Recommendation List

This Research Program for the period July 1, 2018 to June 30, 2020 is submitted in compliance with the provisions of Section 307 of Title 23, United States Code, and describes programs and operations for planning activities in the Kentucky Transportation Cabinet (KYTC) and the Kentucky Cooperative Transportation Research Program (KCTRP). This program modifies and updates such programs and is specifically intended to reflect the needs of the Kentucky Transportation Cabinet. It is fully expected that products from this program will also have national applications. The University of Kentucky Transportation Center is the main research group for the the Kentucky Transportation Cabinet. The SPR grant is the funding the is supplied each year for the many topics the Center is asked to research for KYTC The KCTRP is concerned with the development and conduct of a comprehensive research program in cooperation with the U.S. Department of Transportation, Federal Highway Administration (FHWA). In addition to research developed in cooperation with FHWA, the KCTRP may perform other services for the KYTC on a nonparticipating basis. The scope of these services could include activities such as research studies and special investigations of various engineering and operation activities. The Research Program and Implementation Advisory Committee (RPIAC), headed by the State Highway Engineer and coordinated through the Research Coordinator, will give direction to the research program. PROBLEM STATEMENT Crash Modification Factors (CMFs) are used to adjust crash predictions based on changes in geometrics, typically based on a specific countermeasure. When evaluating design alternatives, CMFs can be used in conjunction with safety performance functions (SPFs) to compute crash predictions. These crash predictions, along with costs associated with the design alternatives, can be useful for making data-driven decisions. The CMF Clearinghouse is a repository for CMFs with contributions from scholars nationwide. The clearinghouse is sortable and filterable, making it easy to find specific CMFs; however, in many cases there are several CMFs for the same countermeasures. Moreover, some CMFs only apply to specific facility or crash types. Selecting the most appropriate CMF for a given application can require extensive review of the associated research that led to the development of the CMF, even despite the star rating system utilized by the clearinghouse. There is a need for a vetted list of practical CMFs to serve as a standard for practitioners in Kentucky as well as guidance tailored for Kentucky highways and conditions. OBJECTIVES This research project intends to cull the clearinghouse and develop a more manageable list of CMFs that are most appropriate for Kentucky applications. Typical design alternatives will be linked to the best CMFs available. This research will explore CMFs as well as CMfunctions (CMFs that vary based on some other variable). In some cases, there may not be CMFs in the clearinghouse specific to KYTC's needs. In this scenario, a search of the literature may help identify CMFs useful for KYTC yet not published in the clearinghouse. The following outlines the tasks related to this research effort.