Minimizing earthwork costs is crucial in the optimization of vertical alignment. In this article, the previous quasi network flow model for the vertical alignment optimization of a single road is extended to a multi-r...
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Minimizing earthwork costs is crucial in the optimization of vertical alignment. In this article, the previous quasi network flow model for the vertical alignment optimization of a single road is extended to a multi-roadnetwork. A 'one-at-a-time' method is first examined to solve the optimization problem and it is noted that this method is effectively what is currently used in practice. Two academic test problems are used to demonstrate that this method is not optimal. This leads to the development of three novel methods to solve the optimization problem: no-flow, with-flow and divide-and-conquer. It is noted that the with-flow method guarantees global optimality. All methods are compared on two real-world case studies. On small roadnetworks, the with-flow method decreases costs by 7.4%, and achieves a 20 times speedup over the one-at-a-time method. On long roadnetworks, the divide-and-conquer method is faster than all other methods without any notable cost difference. However, the divide-and-conquer method is an heuristic and cannot guarantee that it returns a global minimum.
It is important for urban traffic micro-circulation to improve the density of urban branch roadnetworks by opening roads inside blocks. To reasonably optimize the micro-circulation roadnetwork in the open block area...
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It is important for urban traffic micro-circulation to improve the density of urban branch roadnetworks by opening roads inside blocks. To reasonably optimize the micro-circulation roadnetwork in the open block area, a bi-level multi-objective programming model that considers traffic pollution and intersection delays was developed. In this paper, the goals of minimizing traffic pollution and total travel cost are added to the upper-level programming model and the user equilibrium assignment model with the consideration of intersection delay was presented as the lower-level programming model. A modified genetic algorithm (GA) embedded with the Frank-Wolfe algorithm was designed to solve the established model. The traffic conditions of arterial roads and micro-circulation branch roads before and after optimizing the micro-circulation block roadnetwork were compared and analyzed by a numerical example. The results demonstrated that the bi-level programming model can effectively determine the traffic direction of branch roads and the forbidden situation of intersections in the micro-circulation network. Compared with the closed block, the average saturation of the main trunk road decreased from 0.97 to 0.83 with a decline ratio of 14.43% after optimizing the micro-circulation network in the open block area;the average saturation of the secondary trunk road decreased from 0.86 to 0.77, with a decline ratio of 10.47%. The travel time cost decreased by approximately 6.55%, and the traffic pollution decreased by approximately 3.40%, which verified the optimization effect of the model and the algorithm.
To reduce potential noise emissions, an optimization model for planning a roadnetwork that considers traffic noise impact is proposed. First, the urban traffic noise prediction method is constructed with the road str...
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To reduce potential noise emissions, an optimization model for planning a roadnetwork that considers traffic noise impact is proposed. First, the urban traffic noise prediction method is constructed with the road structure as a constraint. Then, the travel time function is built based on the traffic flow model. Furthermore, the road network optimization model is presented based on the minimum network noise cost under different traffic flow states. The results of road structure optimization show the following: 1) Traffic noise cost increases but travel delay increases as travel coefficients increase;2) The road traffic noise cost of the smaller design speed is lower;3) The optimal road structures with various travel coefficients are recommended for distinct optimal objects. 4) The difference between the upper and lower limits of traffic noise pollution under different road structures is within 9 dB. This research can provide a reference for noise control.(c) 2022 Elsevier Ltd. All rights reserved.
In order to improve the road traffic congestion situation, a three-tier optimization model for urban roadnetwork is established from the angle of game relationship after analyzes the game relationship of traffic cong...
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ISBN:
(纸本)9781728100845
In order to improve the road traffic congestion situation, a three-tier optimization model for urban roadnetwork is established from the angle of game relationship after analyzes the game relationship of traffic congestion of urban roadnetwork. The model takes the traffic congestion degree as the lower decision-making objective, takes the degree of traffic pollution impacted on the environment as the middle decision-making objective, and takes the economic cost as the upper decision-making objective. The upper-tier model is aimed at optimizing managers' investment of the roadnetwork operation costs, the medium -tier model is strived to minimize the impact of traffic pollution on the environment, and the lower-tier model is strived to maximize the travel efficiency of roadnetwork. A genetic algorithm solution process is proposed for this model. Taking a regional roadnetwork in Nanjing as an example, the results show that the efficiency of the three-tier optimized roadnetwork is better than the original roadnetwork.
Barrier effect is a road-related impact affecting several animal populations. It can be caused by behavioural responses towards roads (surface and/or gap avoidance), associated emissions (traffic-emissions avoidance) ...
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Barrier effect is a road-related impact affecting several animal populations. It can be caused by behavioural responses towards roads (surface and/or gap avoidance), associated emissions (traffic-emissions avoidance) and/or circulating vehicles (vehicle avoidance). Most studies so far have described road-effect zones along major roads, without determining the actual factor inducing the behavioural response. The purpose of the present study was to assess the factors potentially causing road-effect zones in a heterogeneous roadnetwork (with variations in road width, road surface and traffic volume) and eventually to estimate the reduction of habitat quality imposed by roads within a protected area (Donana Biosphere Reserve, Spain). As model species, we used two ungulates, red deer Cervus elaphus and wild boar Sus scrofa. We surveyed the presence of both species along 200-m transects. All transects started and were perpendicular to reference roads (those with a traffic volume above 10 cars per day), often intersecting unpaved minor roads with virtually no traffic. The presence probability of both species was mainly affected by the distance to the nearest road (in most cases unpaved roads without traffic), but also by the proximity to reference roads. Red deer presence was also affected by the traffic volume of the nearest reference road. At a regional scale, the overall roadnetwork within the protected area imposes a reduction in presence probability of 40% for red deer and 55% for wild boar. A road network optimization, decommissioning unused and unpaved roads, would re-establish almost entirely the potential habitat quality (91% for both species).Synthesis and applications. We found that both study species avoided roads regardless of their surface or traffic volume, suggesting a response due to gap avoidance which may be based on the association between linear infrastructures and the possibility of vehicles occurring along them. The overall behavioural response can
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