This digest is an interim deliverable from NCHRP Project 17-25, Crash Reduction Factors for Traffic Engineering and ITS Improvements, which is being carried out under a contract with The University of North Carolina Highway Safety Research Center (HSRC) under the direction of David L. Harkey (Principal Investigator). Other members of the research team that contributed to this digest include Dr. Raghavan Srinivasan and Charles Zegeer of HSRC; Dr. Bhagwant Persaud and Craig Lyon of Ryerson University; and Kimberly Eccles, Dr. Forrest Council, and Dr. Hugh McGee of BMI-SG.

This digest summarizes the current status of crash reduction factors for a variety of treatments, provides a summary of the best available crash reduction factors, and discusses the relationship between this study and other ongoing research studies that are either documenting or developing additional factors.