Study Details

Study Title: Safety Effect of Dilemma-Zone Protection Using Actuated Advance Warning Systems

Authors: Appiah et al.

Publication Date: JAN, 2011

Abstract: This paper investigates the effectiveness, with respect to safety, of an actuated advance warning dilemma zone protection system developed and implemented at high-speed signalized intersections in Nebraska by the Nebraska department of roads (NDOR). The design algorithm continually monitors an upstream detector as well as traffic at the intersection in order to predict the onset of the yellow signal indication. Flashing beacons are then used to get the driver's attention and also to warn the driver of the impending end of the green indication. While these actuated advance warning systems have received many favorable comments, especially from truck drivers, there has been no comprehensive analysis of their safety effectiveness. This paper compares crash records from before and after the implementation of the NDOR actuated advance warning system at 26 intersections across the state. In addition, 29 control intersections are used to compare crash rates over time using a Bayesian technique to ensure that no exogenous variables affect the results. Results of the analysis are promising (an overall crash reduction rate of eight percent) and suggest that the use of the system should be encouraged as effective safety treatments for the dilemma zone problem at high-speed signalized intersections.

Study Citation: Appiah, J., B. Naik, R. Wojtal, L.R. and Rilett. "Safety Effect of Dilemma-Zone Protection Using Actuated Advance Warning Systems." Transportation Research Record: Journal of the Transportation Research Board, No. 2250, Transportation Research Board of the National Academies, Washington, D.C., 2011, pp. 19-24. DOI: 10.3141/2250-03


CMFs Associated With This Study

Category: Intersection traffic control

Countermeasure: Installation of an actuated advance warning dilemma zone protection system at high-speed signalized intersections

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.988 1.2 4 Stars Rear end All Not specified Not specified
0.564 43.6 4 Stars Angle All Not specified Not specified
0.887 11.3 4 Stars All A,B,C Not specified Not specified
0.995 0.5 4 Stars Truck related All Not specified Not specified
0.918 8.2 4 Stars All All Not specified Not specified