KY-11 is a state highway that runs nearly the entire length of Kentucky from north to south. A rural section of KY 11 in Powell County had a significant curve that saw a high rate of vehicular crashes, including one fatal collision. Many of these crashes were roadway departure crashes that occurred during wet roadway conditions on the narrow two-lane road with limited shoulders. This curve also had a lower design speed and smaller radius than adjacent curves, and sight distance was limited due to a steep backslope along the inside of the curve.

To decrease the potential for collisions, PRIME AE analyzed the curve and determined that water was running along the driving lanes due to deficient superelevation transitions. From there, we developed a range of options for realignment of the curve that met various design speeds while balancing construction cost, potential crash reduction, and utility and right of way impacts. The preferred scenario achieved a 45-mph design speed and cut back the slope inside the curve to increase sight distance.

Our team’s work supported a significant increase in safety for drivers along this dangerous stretch of road. In the three years prior to construction, there was an average of 16 total crashes per year along the corridor, with an average of four KAB (fatal, serious injury, and minor injury) crashes occurring per year. In the two years following construction, those numbers dropped to an average of five total crashes and 0.5 KAB crashes occurred per year, and the increase in safety for drivers is invaluable.