Field Verification of Directional Rumble Strips to Deter Wrong-Way Freeway Driving

This paper summarizes the results of Phase II of a research project developing a novel design of directional rumble strips (DRSs) to deter wrong-way driving (WWD) onto freeway off-ramps. In Phase I of this project, five concept designs of the DRS (named from A to E) were developed to generate elevated sound and vibration to warn against WWD and to generate normal sound and vibration to slow down the right-way (RW) traffic. After initial field tests in Phase I, three final conceptual DRS designs were selected for further field verification, specifically, Patterns C, D3, and E1. Pattern C was designed based on traditional transverse rumble strips (TRSs), but the spacing between the strips was changed to generate different rhythms of sound and vibration. Pattern D3, which was modified based on the advance warning markings for speed humps, increases in thickness and length in each strip. Pattern E1 has a right-angled triangle cross section that can produce the most recognizable sound and vibration from the WWD direction among the three patterns. The objective of this paper was to document the field verification results of the final three patterns and to develop implementation recommendations for applying them on off-ramps. Overall, the field verification results indicated that the tested DRS can generate recognizable interior sound and a moderate amount of vibration to alert wrong-way drivers. Recommendations for implementation were also developed for transportation agencies to identify proper locations for installing them to achieve the best performance based on type and length of off-ramp.