Institute for Transportation

About the research

Installing a traffic signal can be a viable safety countermeasure at high-speed intersections. The FHWA Crash Modification Factors Clearinghouse has several crash modification factors (CMFs) pertaining to installing traffic signals. However, the CMF values can vary widely, originate from studies of various quality levels and analysis periods, and employ data from single geographic regions or states.

The State of Iowa is well positioned to develop Iowa-specific CMFs for signalizing high-speed intersections, given its comprehensive intersection database, quality crash data, and past/ongoing intersection safety performance function (SPF) development efforts. With CMFs developed from Iowa-specific data, agencies within the state may be able to more confidently evaluate the possible benefits of signalization of intersections along high-speed roads. Therefore, the objective of this project is to develop Iowa specific CMFs for installing a traffic signal at high-speed intersections.