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Left turns may generate efficiency problems, which can be solved by appropriately prohibiting left turns. The goal of this paper is to propose a method for purpose of minimizing total travel times in urban road networks by prohibiting left turns. With left turn prohibition, the signal timing plan is optimized with the lane-based method because the method can adequately handle both signal timing optimization and lane assignment. The total travel time is calculated with link flows and link travel time being estimated with signal settings. As illustrated by numerical examples, prohibiting left turns reduces the total travel time of car traffic in road networks. As the left turn prohibition results can handle the randomness in the network, these results provide potential implications for congestion management. [ABSTRACT FROM AUTHOR]

Vehicle turning maneuver is a major design control in roadway alignment, pavement and the placement of curbs at highway intersections. Geometric features, such as the sharper curvature at turning roadways have significant effects on turning maneuverability of vehicles. Due to their wider and longer wheelbases, large vehicles have much more pronounced offtracking and occupy greater swept-path widths. This often creates complex driving operations when large vehicles turn at intersections. The turning maneuvers of large vehicles not only determine roadway design, but also influence the safety and efficiency of intersection operations. Studying turning maneuvers mainly consists of analyzing vehicle turning paths and steering operations. This study presents a computational approach that can simulate vehicle turning maneuverability for given roadway alignments, and also checks for coincidence with design standards. This study also presents field experiments involving tractor-semitrailer truck and bus on roadways with different geometric features. The turning paths of wheels and steering wheel operations were recorded simultaneously. Data from field experiments of different turning angles and roadway geometric features are compared with simulated results of computational approach. This study also analyzes the effects of curve radius and geometric features on turning maneuvers. The precise analysis of vehicle turning maneuvers, including turning paths, swept widths, and steering operations, could help roadway and pavement engineers improve traffic safety and efficiency. [ABSTRACT FROM AUTHOR]