A Study of Driver Behavior at Access Points with Restricted Left Turn Movements: Case Studies in Alabama

Abstract

Past studies showed that left turn movement at unsignalizd intersection caused over 40% crashes. To improve intersection safety, transportation agencies often use access management strategies to eliminate left turns for reducing number of conflicts. One common access management technical used in Alabama is to install channelized island to create right-in and right-out driveways. However, without median treatments, this technique alone may not be able to prevent left turns from driveways. This thesis applied a simple before and after method and a cross sectional comparison method to study the effectiveness of right-in and right-out channelizing island on reducing left turns. An illegal left turn is when a vehicle turns left out of an access onto a major roadway, when they are supposed to turn right only. The objective of this study is to study driver behaviors, such as undesirable movements at access points with restricted left turn design. Seven unsignalized intersections with restricted left-turn designs in Auburn, AL were selected for this study. 72-hour traffic video data were collected at each location. The undesirable movements were recorded for analysis of driver behavior. The descriptive statistical data analysis showed that there were. A cross sectional analysis suggests traffic signage and median types have an impact on driver behavior. The results recommended that channelized islands alone at driveways cannot restrict left-turn movements. It should work together with a raised median, enhanced signage and pavement marking to restrict left turns and make right-turn only intersections safer.