Study Details

Study Title: Evaluation of Sequential Dynamic Chevrons on Rural Two-lane Highways

Authors: Hallmark, S.

Publication Date:MAR, 2017

Abstract: More than 25 percent of fatal crashes are associated with a horizontal curve, and the vast majority of these crashes involve a roadway departure. The average crash rate for horizontal curves is about three times that of other highway segments. Implementing safety countermeasures on rural horizontal curves to address these crash types can improve the safety performance for those locations. Chevron alignment signs provide additional emphasis and guidance for drivers negotiating curves. To further emphasize the curve, some agencies have started using Sequential Dynamic Chevrons (SDC) that provide a sequential pattern of Light Emitting Diodes (LEDs) at the curve. The purpose of this study was to develop a crash modification factor (CMF) for SDCs and determine whether this treatment is effective in reducing crashes, and if so, to what extent. The research team acquired data from a recent study, Publication No. FHWA-HIF-13-040, Evaluation of the TAPCO Sequential Dynamic Curve Warning System, supplementing the results of this study with additional after data and more locations. This project resulted in the evaluation of SDCs at 18 curves where sequential dynamic chevrons had been installed. Control sites were also included. Using this data, the study developed a CMF for SDCs of 0.56 for total crashes (non-intersection) and 0.40 for injury crashes, representing the crash frequency change resulting from upgrading standard chevrons on horizontal curves with SDCs.

Study Citation: Hallmark, S. "Evaluation of Sequential Dynamic Chevrons on Rural Two-lane Highways". Report No. FHWA-TBD. Federal Highway Administration, U.S. Department of Transportation. Washington, D.C. (March 2017).

CMFs Associated With This Study

Category: Signs

Countermeasure: Install sequential dynamic chevrons

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.56444 StarsNon-intersectionAllNot specifiedRural
0.4603 StarsNon-intersectionK,A,B,CNot specifiedRural