Simplifying Delineator and Chevron Applications for Horizontal Curves (0-4052-1)

This research effort focuses on the investigation of methods to simplify horizontal curve delineation treatments without jeopardizing safety. The specific objectives of the research were to simplify delineator and Chevron spacing along horizontal curves, determine a radius above which a horizontal curve on a freeway or expressway may be delineated as a tangent, and explore whether there is any new benefit in using double delineators. The researchers reviewed the Manual on Uniform Traffic Control Devices (MUTCD) evolution with respect to delineation. They also performed a literature review and conducted a state Department of Transportation survey to determine other policies and practices. The research team visited curves throughout the state of Texas to assess the current state-of-the-practice in terms of delineation treatments and test and develop alternative delineation treatment procedures. The researchers also performed a field study to determine drivers' response to an increase in the number of Chevrons installed along horizontal curves. Finally, the researchers performed a closed-course delineator visibility study at the Texas A&M University Riverside campus to assess the need for variable delineator approach and departure spacing on horizontal curves and the need for double delineators (versus single delineators). Using the findings from the previously described activities, the researchers recommended a simplified delineator and Chevron spacing table that is based on the radius or the advisory speed value. Researchers also developed a simple-to-use and accurate field device for measuring the radius of a horizontal curve.