Title: Intersection Sight Distance for Unprotected Left-turn Traffic
Abstract: During the permitted left-turn green phase at intersections on divided highways, if the median of the major road is relatively wide, the simultaneously-turning vehicles in the opposite left-turn lane frequently block the driver’s view. This situation may contribute not only to a serious safety problem because of drivers’ misjudging gaps among the opposing through traffic, but may also lead to needless delays for the left-turning traffic since those cautious drivers reject physically adequate gaps. To improve intersection sight distances and traffic operation for unprotected left-turn drivers at signalized intersections, this study aimed at developing geometric models to calculate sight distance for unprotected left-turning vehicles for different geometric configurations. These models can be used by traffic engineers to lay out intersection configurations or renew the existing left-turn lane design to provide sufficient sight distance and enhance efficiency of the intersection traffic operation. Furthermore, to provide a better understanding of the relationship between highway visibility and traffic operation, a field study was conducted to investigate the influence of the sight-distance problem on left-turn gap-acceptance behaviors and traffic capacity. From field observations and data analysis, this study confirmed the serious negative effect of the sight-distance problem on both traffic safety and operation efficiency for unprotected left-turn traffic.
Publication Year: 2006
Publication Date: 2006-08-01
Language: en
Type: article
Access and Citation
Cited By Count: 1
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