SPEED FACTORS ON LOW-VOLUME ROADS FOR HORIZONTAL CURVES AND TANGENTS

Many studies on driver speed behavior are found in the scientific literature today, and various researchers have addressed roadway alignment consistency for travel safety in context with current operating speeds. Experimental analysis was conducted on low-volume roads in Southern Italy without spiral transition curves between geometric tangent and circular elements on the horizontal alignment. All selected roads are located in areas with level terrain and vertical grades less than 6%. This study will illustrate a methodology, widely employed in the literature, to evaluate at each circular curve transition segment length, the applicable deceleration and acceleration rates. These results were then used to develop four equations for speed prediction models on tangents and curves. These regression equations were developed using a traditional Ordinary-least-squares method involving speed values not surveyed in transition zones. The goal of this research study is to plot continuous speed profiles to illustrate complete driver speed behavior on two-lane rural roads and to individualize critical roadway sections to improve driver safety.