A synchronous optimization model for rehabilitation of existing two-way two-lane(TWTL)highways is proposed in this paper considering geometric modification and existing pavement rehabilitation. The rehabilitation proc...A synchronous optimization model for rehabilitation of existing two-way two-lane(TWTL)highways is proposed in this paper considering geometric modification and existing pavement rehabilitation. The rehabilitation process of existing roadways is categorized into geometric design modifications and pavement repairs. These two types of modification apply separately in roadway life-cycle because of the difference in nature of these repairs, which impose an extra cost and time of closure to road users and owners. This paper aims to address the modification of existing highways by a new approach linking the existing pavement condition and geometric configuration changes of the developed roadway to provide the optimum vertical alignment. The proposed procedure depends on various parameters of existing pavement condition, cross-section configuration, traffic volume and composition, and current alignment composure. In the first step, all these dependencies are explained and quantified with separate cost models. For each solution,the overall cost is calculated with a life-cycle cost analysis approach. Finally, a particle swarm optimization(PSO) based model is developed to find the optimum solution. The developed model was applied in two case studies with good and adverse geometric conditions. The results show that there is a critical condition in the roadway segments which have all these conditions:(1) the grade is more than three percent,(2) the grade is following with reverse grade, and(3) decommissioning of the asphalt concrete(or extended to lower layers) exist. The optimum solution in these critical conditions suggests the modification of the geometric configuration before the pavement rehabilitation in order to reduce the overall cost. In the absence of these conditions, the optimum alignment is more analogous with the existing alignment of the highway.展开更多
文摘A synchronous optimization model for rehabilitation of existing two-way two-lane(TWTL)highways is proposed in this paper considering geometric modification and existing pavement rehabilitation. The rehabilitation process of existing roadways is categorized into geometric design modifications and pavement repairs. These two types of modification apply separately in roadway life-cycle because of the difference in nature of these repairs, which impose an extra cost and time of closure to road users and owners. This paper aims to address the modification of existing highways by a new approach linking the existing pavement condition and geometric configuration changes of the developed roadway to provide the optimum vertical alignment. The proposed procedure depends on various parameters of existing pavement condition, cross-section configuration, traffic volume and composition, and current alignment composure. In the first step, all these dependencies are explained and quantified with separate cost models. For each solution,the overall cost is calculated with a life-cycle cost analysis approach. Finally, a particle swarm optimization(PSO) based model is developed to find the optimum solution. The developed model was applied in two case studies with good and adverse geometric conditions. The results show that there is a critical condition in the roadway segments which have all these conditions:(1) the grade is more than three percent,(2) the grade is following with reverse grade, and(3) decommissioning of the asphalt concrete(or extended to lower layers) exist. The optimum solution in these critical conditions suggests the modification of the geometric configuration before the pavement rehabilitation in order to reduce the overall cost. In the absence of these conditions, the optimum alignment is more analogous with the existing alignment of the highway.
