Roads are a leading cause of habitat fragmentation and may reduce bird populations by increasing nest predation rates.However,few studies have investigated the effects of traffic volume on the reproductive success of ...Roads are a leading cause of habitat fragmentation and may reduce bird populations by increasing nest predation rates.However,few studies have investigated the effects of traffic volume on the reproductive success of roadside birds in the neotropics.Our goal was to evaluate the effects of spatial,temporal,and vehicle flow variations on the survival of artificial open-cup nests.The study was carried out in a nature reserve on the side of a highway during the breeding season(from October to March)in two restinga(sand-coastal plain)phytophysiognomies in southeastern Brazil:non-floodable(open)and floodable(closed).One hundred thirty nests were distributed along transects ranging from 3 m to 300 m from the highway in each vegetation type(totaling 260 nests).The nests were checked every three days for their status(depredated or intact)over 12 days,and new nests were subsequently placed near sampling points of depredated or successful nests.We estimated survival using logistic exposure generalized linear and additive mixed models.At the end of the 180 days of the experiment,33%of 6202 nests were successful.Nest survival was higher in open restinga than in closed restinga.In both habitats,nest survival was lowest mid-season and highest at the beginning and end.Survival rates peaked near the highway,declined up to 50 m away,then showed a slight increase.Finally,survival increased at moderate-to-high traffic volumes(∼22,000 vehicles/day),particularly in open restinga.We suggest that spatial,temporal,and habitat-specific highway impacts(e.g.,noise,vibration,visual stimuli)can lead to variations in the activity of nest predators,generating fluctuations in nest survival associated with predator behavior.展开更多
By introducing the traffic anticipation effect in the real world into the original lattice hydrodynamic model, we present a new anticipation effect lattice hydrodynamic （AELH） model, and obtain the linear stability ...By introducing the traffic anticipation effect in the real world into the original lattice hydrodynamic model, we present a new anticipation effect lattice hydrodynamic （AELH） model, and obtain the linear stability condition of the model by applying the linear stability theory. Through nonlinear analysis, we derive the Burgers equation and Korteweg-de Vries （KdV） equation, to describe the propagating behaviour of traffic density waves in the stable and the metastable regions, respectively. The good agreement between simulation results and analytical results shows that the stability of traffic flow can be enhanced when the anticipation effect is considered.展开更多
In this paper, we study the effect of moving bottlenecks on traffic flow. The full velocity difference （FVD） model is extended to the traffic flow on a two-lane highway, and new lane changing rule is proposed to rep...In this paper, we study the effect of moving bottlenecks on traffic flow. The full velocity difference （FVD） model is extended to the traffic flow on a two-lane highway, and new lane changing rule is proposed to reproduce the vehicular lane changing behavior. Using this model, we derive the fundamental current-density diagrams for the traffic flow with the effect of moving bottleneck. Moreover, typical time-space diagram for a two-lane highway shows the formation and dissipation of a moving bottleneck. Results demonstrate that the effect of moving bottleneck enlarges with the increase of traffic density, but the effect can be reduced by increasing the maximum velocity of heavy truck. The effects of multiple moving bottlenecks under different conditions are investigated. The effect becomes more remarkable when the coupling effect of multiple moving bottlenecks occurs.展开更多
A new higher-order continuum model is proposed by considering the coupling and lane changing effects of the vehicles on two adjacent lanes. A stability analysis of the proposed model provides the conditions that ensur...A new higher-order continuum model is proposed by considering the coupling and lane changing effects of the vehicles on two adjacent lanes. A stability analysis of the proposed model provides the conditions that ensure its linear stability. Issues related to lane changing, shock waves and rarefaction waves, local clustering and phase transition are also investigated with numerical experiments. The simulation results show that the proposed model is capable of providing explanations to some particular traffic phenomena commonly observable in real traffic flows.展开更多
Taking into account the startup behaviour of following vehicles in the waiting area of urban traffic signal, we propose an extended Nagel-Schreckenberg model for single-lane traffic flow, in which the dynamic behavior...Taking into account the startup behaviour of following vehicles in the waiting area of urban traffic signal, we propose an extended Nagel-Schreckenberg model for single-lane traffic flow, in which the dynamic behavior of each vehicle depends on not only its own headway but also the headway of the immediately preceding one. The numerical simulation of the present model reproduces some complicated nonlinear phenomena observed in real traffic such as free flow, ghostly blockage, synchronized flow and so on. For specific parameter combinations the flow-density relation of this model shows two meta-stable branches near the transition density from free flow to wide moving traffic jam. Finally, the analytical results of the model under some specific parameters are given by using the mean field theory.展开更多
The Generalized Markov Fluid Model (GMFM), introduced in [1], is assumed for modeling sources in the network because it is versatile to describe the traffic fluctuations. In order to estimate resources allocations or ...The Generalized Markov Fluid Model (GMFM), introduced in [1], is assumed for modeling sources in the network because it is versatile to describe the traffic fluctuations. In order to estimate resources allocations or in other words the channel occupation of each source, the concept of effective bandwidth proposed by Kelly [2] is used. In this paper, we present a formula for calculating the effective bandwidth, developed for the Generalized Markovian Flow model, which is of particular interest because it allows expressing said magnitude depending on the parameters of the model. We present unbiased estimators for these parameters that can be obtained from real data. The convergence and the consistency of the estimation are studied, and confidence bands are found. Illustrative calculation and performance of the proposed estimators were tested with simulated data and ideal results were obtained.展开更多
To measure the length of traffic queue, a vehicle motion model at intersections was built, and based on it the effective traffic queue was def＇med. Color images segmentation and frame differencing technique were used...To measure the length of traffic queue, a vehicle motion model at intersections was built, and based on it the effective traffic queue was def＇med. Color images segmentation and frame differencing technique were used to detect the foreground and the moving vehicles by detecting regions of the images, and then measure the length of effective traffic queue. By processing the image sequence acquired at certain intersection, the results prove that it is able to work out the traffic queue effectively by using the two techniques.展开更多
Mashhad, the second largest city in Iran, like many other big cities, is faced with increasing traffic congestion owing to rapidly increasing population and annual pilgrimage. In recent years, Mashhad traffic and tran...Mashhad, the second largest city in Iran, like many other big cities, is faced with increasing traffic congestion owing to rapidly increasing population and annual pilgrimage. In recent years, Mashhad traffic and transportation authorities have been challenged with how to manage the increasing congestion with limited budgets for major roadway construction projects. Mashhad has recognized the need to improve the existing system capacity to get the most out of their cur- rent transportation system infrastructures. Since most of the delay times occur at signalized intersections, using an intelligent control system with proper capabilities to overcome the growing traffic requirements is recommended. Following comprehensive studies carried out with the aim of developing the Mashhad traffic control center, the SCATS adaptive traffic control system was introduced as the selected intelligent control system for integrating signalized intersections. The first intersection was equipped with this system in 2005. This paper describes the results of a field evaluation in which fixed actuated-coordinated signal timings are compared with those dynamically computed by SCATS. The ef- fects of this system on optimizing fuel consumption as well as reducing air pollutants are fully discussed. It is found that SCATS consistently reduced travel times and the average delay per stopped or approaching vehicle. The positive impact of adaptive traffic control systems on fuel consumption and air pollution are also highlighted.展开更多
In order to exhibit the meta-stable states, several slow-to-start rules have been investigated as modification to Nagel-Schreckenberg （NS） model. These models can reproduce some realistic phenomena which are absent ...In order to exhibit the meta-stable states, several slow-to-start rules have been investigated as modification to Nagel-Schreckenberg （NS） model. These models can reproduce some realistic phenomena which are absent in the original NS model. But in these models, the size of cluster is still not considered as a useful parameter. In real traffic, the slow-to-start motion of a standing vehicle often depends on the degree of congestion which can be measured by the clusters＇ size. According to this idea, we propose a cluster-size dependent slow-to-start model based on the speed- dependent slow-to-start rule （VDR） model. It gives expected results through simulations. Comparing with the VDR model, our new model has a better traffic efficiency and shows richer complex characters.展开更多
The measurements on actual traffic have revealed the existence of meta-stable states with high flow. Such nonlinear phenomena have not been observed in the classic Nagel-Schreckenberg traffic flow model. Here we just ...The measurements on actual traffic have revealed the existence of meta-stable states with high flow. Such nonlinear phenomena have not been observed in the classic Nagel-Schreckenberg traffic flow model. Here we just add a constraint to the classic model by introducing a velocity-dependent randomization. Two typical randomization strategies are adopted in this paper. It is shown that the Matthew effect is a necessary condition to induce traffic meta-stable states, thus shedding a light on the prerequisites for the emergence of hysteresis loop in the fundamental diagrams.展开更多
基金supports were provided by the Concessionária Rodovia do Sol/SA(RodoSol)the Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq,grant:45.6446/2014/1)+2 种基金the São Paulo Research Foundation(FAPESP,Process Number#2024/13237-3)PD received a postdoctoral fellowship from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior(CAPES,grant:88887.469218/2019-00)CD is grateful to CNPq(Bolsa de Produtividade em Pesquisa,grant:308997/2023-9).
文摘Roads are a leading cause of habitat fragmentation and may reduce bird populations by increasing nest predation rates.However,few studies have investigated the effects of traffic volume on the reproductive success of roadside birds in the neotropics.Our goal was to evaluate the effects of spatial,temporal,and vehicle flow variations on the survival of artificial open-cup nests.The study was carried out in a nature reserve on the side of a highway during the breeding season(from October to March)in two restinga(sand-coastal plain)phytophysiognomies in southeastern Brazil:non-floodable(open)and floodable(closed).One hundred thirty nests were distributed along transects ranging from 3 m to 300 m from the highway in each vegetation type(totaling 260 nests).The nests were checked every three days for their status(depredated or intact)over 12 days,and new nests were subsequently placed near sampling points of depredated or successful nests.We estimated survival using logistic exposure generalized linear and additive mixed models.At the end of the 180 days of the experiment,33%of 6202 nests were successful.Nest survival was higher in open restinga than in closed restinga.In both habitats,nest survival was lowest mid-season and highest at the beginning and end.Survival rates peaked near the highway,declined up to 50 m away,then showed a slight increase.Finally,survival increased at moderate-to-high traffic volumes(∼22,000 vehicles/day),particularly in open restinga.We suggest that spatial,temporal,and habitat-specific highway impacts(e.g.,noise,vibration,visual stimuli)can lead to variations in the activity of nest predators,generating fluctuations in nest survival associated with predator behavior.
基金supported by the Fundamental Research Funds for the Central Universities (Grant No. CDJZR11170002)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20090191110022)
文摘By introducing the traffic anticipation effect in the real world into the original lattice hydrodynamic model, we present a new anticipation effect lattice hydrodynamic （AELH） model, and obtain the linear stability condition of the model by applying the linear stability theory. Through nonlinear analysis, we derive the Burgers equation and Korteweg-de Vries （KdV） equation, to describe the propagating behaviour of traffic density waves in the stable and the metastable regions, respectively. The good agreement between simulation results and analytical results shows that the stability of traffic flow can be enhanced when the anticipation effect is considered.
基金Project supported by the National Natural Science Foundation of China (Grant No.11102165)the Natural Science Basis Research Plan in Shaanxi Province,China (Grant No.2012JM1001)the Foundation for Fundamental Research of Northwestern Polytechnical University,China (Grant No.NPU-FFR-JC201254)
文摘In this paper, we study the effect of moving bottlenecks on traffic flow. The full velocity difference （FVD） model is extended to the traffic flow on a two-lane highway, and new lane changing rule is proposed to reproduce the vehicular lane changing behavior. Using this model, we derive the fundamental current-density diagrams for the traffic flow with the effect of moving bottleneck. Moreover, typical time-space diagram for a two-lane highway shows the formation and dissipation of a moving bottleneck. Results demonstrate that the effect of moving bottleneck enlarges with the increase of traffic density, but the effect can be reduced by increasing the maximum velocity of heavy truck. The effects of multiple moving bottlenecks under different conditions are investigated. The effect becomes more remarkable when the coupling effect of multiple moving bottlenecks occurs.
基金supported by the National High Technology Research and Development Program of China(863)(511-0910-1031)the National"10th Five-Year"Science and Technique Important Program of China(2002BA404A07)
文摘A new higher-order continuum model is proposed by considering the coupling and lane changing effects of the vehicles on two adjacent lanes. A stability analysis of the proposed model provides the conditions that ensure its linear stability. Issues related to lane changing, shock waves and rarefaction waves, local clustering and phase transition are also investigated with numerical experiments. The simulation results show that the proposed model is capable of providing explanations to some particular traffic phenomena commonly observable in real traffic flows.
文摘Taking into account the startup behaviour of following vehicles in the waiting area of urban traffic signal, we propose an extended Nagel-Schreckenberg model for single-lane traffic flow, in which the dynamic behavior of each vehicle depends on not only its own headway but also the headway of the immediately preceding one. The numerical simulation of the present model reproduces some complicated nonlinear phenomena observed in real traffic such as free flow, ghostly blockage, synchronized flow and so on. For specific parameter combinations the flow-density relation of this model shows two meta-stable branches near the transition density from free flow to wide moving traffic jam. Finally, the analytical results of the model under some specific parameters are given by using the mean field theory.
文摘The Generalized Markov Fluid Model (GMFM), introduced in [1], is assumed for modeling sources in the network because it is versatile to describe the traffic fluctuations. In order to estimate resources allocations or in other words the channel occupation of each source, the concept of effective bandwidth proposed by Kelly [2] is used. In this paper, we present a formula for calculating the effective bandwidth, developed for the Generalized Markovian Flow model, which is of particular interest because it allows expressing said magnitude depending on the parameters of the model. We present unbiased estimators for these parameters that can be obtained from real data. The convergence and the consistency of the estimation are studied, and confidence bands are found. Illustrative calculation and performance of the proposed estimators were tested with simulated data and ideal results were obtained.
基金The Cultivation Fund of the Key Scientif-ic and Technical Innovation Project,Ministry of Education of China
文摘To measure the length of traffic queue, a vehicle motion model at intersections was built, and based on it the effective traffic queue was def＇med. Color images segmentation and frame differencing technique were used to detect the foreground and the moving vehicles by detecting regions of the images, and then measure the length of effective traffic queue. By processing the image sequence acquired at certain intersection, the results prove that it is able to work out the traffic queue effectively by using the two techniques.
文摘Mashhad, the second largest city in Iran, like many other big cities, is faced with increasing traffic congestion owing to rapidly increasing population and annual pilgrimage. In recent years, Mashhad traffic and transportation authorities have been challenged with how to manage the increasing congestion with limited budgets for major roadway construction projects. Mashhad has recognized the need to improve the existing system capacity to get the most out of their cur- rent transportation system infrastructures. Since most of the delay times occur at signalized intersections, using an intelligent control system with proper capabilities to overcome the growing traffic requirements is recommended. Following comprehensive studies carried out with the aim of developing the Mashhad traffic control center, the SCATS adaptive traffic control system was introduced as the selected intelligent control system for integrating signalized intersections. The first intersection was equipped with this system in 2005. This paper describes the results of a field evaluation in which fixed actuated-coordinated signal timings are compared with those dynamically computed by SCATS. The ef- fects of this system on optimizing fuel consumption as well as reducing air pollutants are fully discussed. It is found that SCATS consistently reduced travel times and the average delay per stopped or approaching vehicle. The positive impact of adaptive traffic control systems on fuel consumption and air pollution are also highlighted.
基金Project supported by the State Key Development Program for Basic Research of China （Grant No 2006CB705500）, the National Natural Science Foundation of China （Grant Nos 10472116, 10532060, and 70571074）, the Special Research Funds for Theoretical Physics Frontier Problems （Grant Nos 10547004 and A0524701）, the Presidential Foundation of the Chinese Academy of Sciences, and the Specialized Rescarch Fund for the Doctoral Program of High Education of China.
文摘In order to exhibit the meta-stable states, several slow-to-start rules have been investigated as modification to Nagel-Schreckenberg （NS） model. These models can reproduce some realistic phenomena which are absent in the original NS model. But in these models, the size of cluster is still not considered as a useful parameter. In real traffic, the slow-to-start motion of a standing vehicle often depends on the degree of congestion which can be measured by the clusters＇ size. According to this idea, we propose a cluster-size dependent slow-to-start model based on the speed- dependent slow-to-start rule （VDR） model. It gives expected results through simulations. Comparing with the VDR model, our new model has a better traffic efficiency and shows richer complex characters.
文摘The measurements on actual traffic have revealed the existence of meta-stable states with high flow. Such nonlinear phenomena have not been observed in the classic Nagel-Schreckenberg traffic flow model. Here we just add a constraint to the classic model by introducing a velocity-dependent randomization. Two typical randomization strategies are adopted in this paper. It is shown that the Matthew effect is a necessary condition to induce traffic meta-stable states, thus shedding a light on the prerequisites for the emergence of hysteresis loop in the fundamental diagrams.
