Development of an Improved Method for Determining Advisory Speeds on Horizontal Curves

Horizontal curves are an integral part of the highway alignment. However, a disproportionately high number of severe crashes occur on them. One method transportation agencies use to reduce the number crashes at horizontal curves is the installation of curve warning signs which post an appropriate advisory speed. Appropriate curve advisory speeds can be determined using several methods. Some of these methods are time-consuming to perform and are error-prone. The purpose of this research was to find the most efficient and accurate data collection method for determining curve advisory speeds. Several processes were developed and tested. They were then validated against the results of a manual process referred to as the Direct Method and other traditional methods (such as the ball-bank indicator), which are generally assumed to produce accurate results. Comparing the results of these methods allow researchers evaluate their accuracy and usefulness for setting advisory speeds. The results illustrate the potential of a more user-friendly methodology that allows for efficient and accurate data collection. The advisory speeds determined by this research will assist the Kentucky Transportation Cabinet to properly sign horizontal curves. Previous research suggests that posting appropriate advisory speeds results in a safer driving experience