Passing Zone Behavior and Sight Distance on Rural Highways

PI: Nathan Belz (UAF),
Dates: 01/16/2015 – 06/15/2016
Status: Completed
UTC Project Sheet
Final Technical Report

In 2008, more than 27 percent of fatal crashes occurred at horizontal curves. Due to the predominance of horizontal curves on typical rural roads, a higher percentage of fatal curve-related crashes occur on rural roads, particularly on two-lane roadways in rural areas; fatality rates on rural roads are typically more than twice the rate than on urban roads. Of all fatal crashes that occur on two-lane rural highways, about 20% are head on collisions with passing being the main cause of this type of crash.The Alaska Department of Transportation (AKDOT) and the University of Alaska Fairbanks (UAF) have identified a critical need to assess the current standards for passing zone requirements on two-lane highways in the context of horizontal and vertical alignment configurations. The project will provide a better understanding of a drivers’ passing behavior under varied geometric conditions in order to evaluate how the degree and mix of curvature influence driver behavior. This project will improve upon current American Association of State Highway Transportation Officials (AASHTO) guidelines and provide DOTs with better criteria by which geometric roadway configurations can be designed and evaluated in order to improve the safety and efficiency of traffic operations. More specifically, this project seeks to improve the current standards on which the decision to provide or not provide passing zones in a particular context are made.