Traffic simulators are utilized to solve a variety of traffic-related problems.For such simulators,origin-destination(OD)traffic volumes as mobility demands are required to input,and we need to estimate them.The autho...Traffic simulators are utilized to solve a variety of traffic-related problems.For such simulators,origin-destination(OD)traffic volumes as mobility demands are required to input,and we need to estimate them.The authors regard an OD estimation as a bi-level programming problem,and apply a microscopic traffic simulation model to it.However,the simulation trials can be computationally expensive if full dynamic rerouting is allowed,when employing multi-agent-based models in the estimation process.This paper proposes an efficient OD estimation method using a multi-agent-based simulator with restricted dynamic rerouting to reduce the computational load.Even though,in the case of large traffic demand,the restriction on dynamic rerouting can result in heavier congestion.The authors resolve this problem by introducing constraints of the bi-level programming problem depending on link congestion.Test results show that the accuracy of the link traffic volume reproduced with the proposed method is virtually identical to that of existing methods but that the proposed method is more computationally efficient in a wide-range or high-demand context.展开更多
Road traffic congestion has become an everyday phenomenon in today's cities all around the world.The reason is clear:at peak hours,the road network operates at full capacity.In this way,growing traffic demand cann...Road traffic congestion has become an everyday phenomenon in today's cities all around the world.The reason is clear:at peak hours,the road network operates at full capacity.In this way,growing traffic demand cannot be satisfied,not even with traffic-responsive signal plans.The external impacts of traffic congestion come with a serious socio-economic cost:air pollution,increased travel times and fuel consumption,stress,as well as higher risk of accidents.To tackle these problems,a number of European cities have implemented reduced speed limit measures.Similarly,a general urban speed limit measure is in preparatory phase in Budapest,Hungary.In this context,a complex preliminary impact assessment is needed using a simulated environment.Two typical network parts of Budapest were analyzed with microscopic traffic simulations.The results revealed that speed limits can affect traffic differently in diverse network types indicating that thorough examination and preparation works are needed prior to the introduction of speed limit reduction.展开更多
Some microscopic traffic simulations on urban road network are developed up to now. However, the effect of urban transport policy in the local city is influenced with the complex interaction of automobile traffic and ...Some microscopic traffic simulations on urban road network are developed up to now. However, the effect of urban transport policy in the local city is influenced with the complex interaction of automobile traffic and public transport traffic. Particularly, behaviours of vehicles should be described with the fuzziness of the subjective recognition and operation. On the other hand, the trip makers are influenced by various transport policies in terms of mode choice behaviour. The change in mode choice behaviour and number of public transport mode users would eventually affect traffic flow conditions on road network. Modal spilt and traffic conditions of a network are interrelated. Therefore, the present study mainly aims to integrate mode choice model and microscopic traffic simulation model based on fuzzy logic. In the study, the fuzzy logic based mode choice model is proposed. The proposed mode choice model and the existing microscopic traffic simulation model are combined. The developed model has been applied on real urban network to demonstrate the effectiveness of the installation of LRT system. Finally, it is helpful for evaluation of transport policy that the fuzzy logic based microscopic traffic simulation with modal choice model has been constructed.展开更多
This research presented a bi-level programming approach to optimize the schedule of ur- ban road construction activities based on a hypothetical transport network, with an objective of mini- mizing the overall traffic...This research presented a bi-level programming approach to optimize the schedule of ur- ban road construction activities based on a hypothetical transport network, with an objective of mini- mizing the overall traffic delays. A heuristic algorithm was utilized to identify a set of road construction schedules, while PARAMICS was adopted to estimate the total travel time in the network under each road construction scenario. To test the performance of proposed heuristics-simulation methodology, a numerical test was implemented. The overall results suggested that the proposed methodol- ogy could quickly find the optimum solution with good convergence.展开更多
This study involved investigating the sensitivity of Measures of Effectiveness （MOEs） to different simulation initialization time （7, 10, and 13 minutes）; observing the trend of variation of MOEs with increasing s...This study involved investigating the sensitivity of Measures of Effectiveness （MOEs） to different simulation initialization time （7, 10, and 13 minutes）; observing the trend of variation of MOEs with increasing simulation runs; and identifying the major contributors of variation in MOEs using CORSIM and SimTraffic. The results showed that （1） the MOEs of a simulated intersection approaches were indeed sensitive to initialization times; （2） the variation within MOEs reached a steady state with increased number of simulation runs, while CORSIM required at least 50 simulation runs, SimTraffic required even higher number of runs for congested approaches; （3） lane changing and gap acceptance parameters play a major role as a source of variation of MOEs （delay/vehicle） in CORSIM and SimTraffic respectively.展开更多
In the paper the aim and meaning of traffic microscopic simulation is discussed first, and then three sub-models of the system are established, e. i. the model for random generation of the vehicles, the model for car-...In the paper the aim and meaning of traffic microscopic simulation is discussed first, and then three sub-models of the system are established, e. i. the model for random generation of the vehicles, the model for car-following and lane change influenced by an adjacent vehicle, and the model for control and optimization of intersection with signal. Optimization of the traffic signal timing with a genetic algorithm and a microscopic simulation is carried out. It represents a novel approach to solving optimal signal timing.展开更多
Recently,the demand for comprehension of mixed traffic in developing countries,particularly at roundabouts,which are highly interactive road junctions,has increased.Thus,we analyzed mixed traffic at roundabouts,consid...Recently,the demand for comprehension of mixed traffic in developing countries,particularly at roundabouts,which are highly interactive road junctions,has increased.Thus,we analyzed mixed traffic at roundabouts,considering Vietnam as a case study.The two main objectives of this study were to characterize the mixed traffic in Vietnam and to determine the microscopic characteristics of motorcycles at roundabouts.First,efforts were made to clarify the two constitutions of mixed traffic(the performance rule and the presence of small-sized vehicles),and the term“motorcycle-oriented mixed traffic”was defined.Even when satisfying the two fundamental constitutions,this traffic state has unique features,e.g.,only one type of non-lane-based vehicle(the motorcycle)and the predominance of motorcycles in the traffic composition(91.7%).Second,four microscopic characteristics of motorcycles were obtained from a large dataset:the motorcycles’continuous changes in speed,the relationship between the turning angle rate and the speed,the critical gap,and the following space.The relationship between the turning angle rate and the speed was first formulated as a power curve.The critical gap of motorcycles was estimated as a small value(1.25 s)in the case study.The following spaces varied with respect to the speed and had an oval shape.The smallest lateral and longitudinal dimensions were 1.5 and 1.74 m,respectively.While all the findings are meaningful,they are restricted to the case study(Ho Chi Minh City,Vietnam).展开更多
In a multi-lane area,the increasing randomness of lane changes contributes to traffic insecurity and local traffic flow instability.A study on safe lane shifting activity that focuses on threat assessment under real-t...In a multi-lane area,the increasing randomness of lane changes contributes to traffic insecurity and local traffic flow instability.A study on safe lane shifting activity that focuses on threat assessment under real-time knowledge is necessary to enhance smooth vehicle flow.This paper proposed amore comprehensive lane changing guidance rule to investigate the status of surrounding vehicles to accommodate future vehicle-on-road collaborative environments based on these parameters 1)lane change demand and 2)treat assessment function.The collaborative relationships between vehicles are analyzed using a cellular automata model based on their location,velocity,and acceleration.We analyze and examine the relationship between the number of lanes and traffic flow when the road capacity is heavily mined via intelligent lane changing.Our analysis can further provide theoretical guidance for the selection of road expansion mode.Our proposed STCA-L is compared based on the average speed,average flow,lane changing frequency,spatial and temporal pattern of STCA,STCA-I,and STCA-S,and STCA-M under different vehicle densities.The numerical simulation results show that our proposed STCA-L provides themost flexible lane changing guidance in the multi-lanes road.Moreover,the simulated results show that the exponential growth of physical space cannot provide the corresponding increase in the average flow of vehicles.展开更多
Purpose–Freeway work zones have been traffic bottlenecks that lead to a series of problems,including long travel time,high-speed variation,driver’s dissatisfaction and traffic congestion.This research aims to develo...Purpose–Freeway work zones have been traffic bottlenecks that lead to a series of problems,including long travel time,high-speed variation,driver’s dissatisfaction and traffic congestion.This research aims to develop a collaborative component of connected and automated vehicles(CAVs)to alleviate negative effects caused by work zones.Design/methodology/approach–The proposed cooperative component is incorporated in a cellular automata model to examine how and to what scale CAVs can help in improving traffic operations.Findings–Simulation results show that,with the proposed component and penetration of CAVs,the average performances(travel time,safety and emission)can all be improved and the stochasticity of performances will be minimized too.Originality/value–To the best of the authors’knowledge,this is the first research that develops a cooperative mechanism of CAVs to improve work zone performance.展开更多
This study evaluated the operational performance of Transit Signal Priority(TSP)using a microscopic simulation approach.The analysis was based on a 10-mile study corridor in South Florida.Two microscopic VISSIM simula...This study evaluated the operational performance of Transit Signal Priority(TSP)using a microscopic simulation approach.The analysis was based on a 10-mile study corridor in South Florida.Two microscopic VISSIM simulation models were developed:a Base model,calibrated and validated to represent field conditions,and a TSP model.With TSP,the study corridor experienced up to 8%reduction in travel times and up to 13.3% reduction in average vehicle delay time,for both buses and all other vehicles.To better quantify the mobility benefits of the TSP strategy,Mobility Enhancement Factors(MEFs)were developed,unlike previous studies.A MEF is a multiplicative factor to estimate the expected mobility level after implementing TSP at a specific site.A MEF<1 implies that the TSP yields mobility benefits.TSP’s impact on cross-streets were also estimated.The study results indicate TSP strategy has enhanced mobility for buses and all other vehicles.展开更多
基金supported by JSPS KAKENHI (Grant Nos.15H01785 and 19H02377).
文摘Traffic simulators are utilized to solve a variety of traffic-related problems.For such simulators,origin-destination(OD)traffic volumes as mobility demands are required to input,and we need to estimate them.The authors regard an OD estimation as a bi-level programming problem,and apply a microscopic traffic simulation model to it.However,the simulation trials can be computationally expensive if full dynamic rerouting is allowed,when employing multi-agent-based models in the estimation process.This paper proposes an efficient OD estimation method using a multi-agent-based simulator with restricted dynamic rerouting to reduce the computational load.Even though,in the case of large traffic demand,the restriction on dynamic rerouting can result in heavier congestion.The authors resolve this problem by introducing constraints of the bi-level programming problem depending on link congestion.Test results show that the accuracy of the link traffic volume reproduced with the proposed method is virtually identical to that of existing methods but that the proposed method is more computationally efficient in a wide-range or high-demand context.
基金supported by the National Laboratory for Autonomous Systems fund of the Hungarian Ministry for Innovation and Technology(2019-2.1.7-ERA-NET-2021-00019).
文摘Road traffic congestion has become an everyday phenomenon in today's cities all around the world.The reason is clear:at peak hours,the road network operates at full capacity.In this way,growing traffic demand cannot be satisfied,not even with traffic-responsive signal plans.The external impacts of traffic congestion come with a serious socio-economic cost:air pollution,increased travel times and fuel consumption,stress,as well as higher risk of accidents.To tackle these problems,a number of European cities have implemented reduced speed limit measures.Similarly,a general urban speed limit measure is in preparatory phase in Budapest,Hungary.In this context,a complex preliminary impact assessment is needed using a simulated environment.Two typical network parts of Budapest were analyzed with microscopic traffic simulations.The results revealed that speed limits can affect traffic differently in diverse network types indicating that thorough examination and preparation works are needed prior to the introduction of speed limit reduction.
文摘Some microscopic traffic simulations on urban road network are developed up to now. However, the effect of urban transport policy in the local city is influenced with the complex interaction of automobile traffic and public transport traffic. Particularly, behaviours of vehicles should be described with the fuzziness of the subjective recognition and operation. On the other hand, the trip makers are influenced by various transport policies in terms of mode choice behaviour. The change in mode choice behaviour and number of public transport mode users would eventually affect traffic flow conditions on road network. Modal spilt and traffic conditions of a network are interrelated. Therefore, the present study mainly aims to integrate mode choice model and microscopic traffic simulation model based on fuzzy logic. In the study, the fuzzy logic based mode choice model is proposed. The proposed mode choice model and the existing microscopic traffic simulation model are combined. The developed model has been applied on real urban network to demonstrate the effectiveness of the installation of LRT system. Finally, it is helpful for evaluation of transport policy that the fuzzy logic based microscopic traffic simulation with modal choice model has been constructed.
基金Supported by the National Natural Science Foundation of China(71131001)
文摘This research presented a bi-level programming approach to optimize the schedule of ur- ban road construction activities based on a hypothetical transport network, with an objective of mini- mizing the overall traffic delays. A heuristic algorithm was utilized to identify a set of road construction schedules, while PARAMICS was adopted to estimate the total travel time in the network under each road construction scenario. To test the performance of proposed heuristics-simulation methodology, a numerical test was implemented. The overall results suggested that the proposed methodol- ogy could quickly find the optimum solution with good convergence.
文摘This study involved investigating the sensitivity of Measures of Effectiveness （MOEs） to different simulation initialization time （7, 10, and 13 minutes）; observing the trend of variation of MOEs with increasing simulation runs; and identifying the major contributors of variation in MOEs using CORSIM and SimTraffic. The results showed that （1） the MOEs of a simulated intersection approaches were indeed sensitive to initialization times; （2） the variation within MOEs reached a steady state with increased number of simulation runs, while CORSIM required at least 50 simulation runs, SimTraffic required even higher number of runs for congested approaches; （3） lane changing and gap acceptance parameters play a major role as a source of variation of MOEs （delay/vehicle） in CORSIM and SimTraffic respectively.
文摘In the paper the aim and meaning of traffic microscopic simulation is discussed first, and then three sub-models of the system are established, e. i. the model for random generation of the vehicles, the model for car-following and lane change influenced by an adjacent vehicle, and the model for control and optimization of intersection with signal. Optimization of the traffic signal timing with a genetic algorithm and a microscopic simulation is carried out. It represents a novel approach to solving optimal signal timing.
文摘Recently,the demand for comprehension of mixed traffic in developing countries,particularly at roundabouts,which are highly interactive road junctions,has increased.Thus,we analyzed mixed traffic at roundabouts,considering Vietnam as a case study.The two main objectives of this study were to characterize the mixed traffic in Vietnam and to determine the microscopic characteristics of motorcycles at roundabouts.First,efforts were made to clarify the two constitutions of mixed traffic(the performance rule and the presence of small-sized vehicles),and the term“motorcycle-oriented mixed traffic”was defined.Even when satisfying the two fundamental constitutions,this traffic state has unique features,e.g.,only one type of non-lane-based vehicle(the motorcycle)and the predominance of motorcycles in the traffic composition(91.7%).Second,four microscopic characteristics of motorcycles were obtained from a large dataset:the motorcycles’continuous changes in speed,the relationship between the turning angle rate and the speed,the critical gap,and the following space.The relationship between the turning angle rate and the speed was first formulated as a power curve.The critical gap of motorcycles was estimated as a small value(1.25 s)in the case study.The following spaces varied with respect to the speed and had an oval shape.The smallest lateral and longitudinal dimensions were 1.5 and 1.74 m,respectively.While all the findings are meaningful,they are restricted to the case study(Ho Chi Minh City,Vietnam).
基金supported in part by the National Natural Science Foundation of China(No.51905405)Basic Research Program of Natural Science of Shaanxi Province(No.2022JM-407)Guiding Program of Science and Technology of China Textile Industry Federation(No.2020106).
文摘In a multi-lane area,the increasing randomness of lane changes contributes to traffic insecurity and local traffic flow instability.A study on safe lane shifting activity that focuses on threat assessment under real-time knowledge is necessary to enhance smooth vehicle flow.This paper proposed amore comprehensive lane changing guidance rule to investigate the status of surrounding vehicles to accommodate future vehicle-on-road collaborative environments based on these parameters 1)lane change demand and 2)treat assessment function.The collaborative relationships between vehicles are analyzed using a cellular automata model based on their location,velocity,and acceleration.We analyze and examine the relationship between the number of lanes and traffic flow when the road capacity is heavily mined via intelligent lane changing.Our analysis can further provide theoretical guidance for the selection of road expansion mode.Our proposed STCA-L is compared based on the average speed,average flow,lane changing frequency,spatial and temporal pattern of STCA,STCA-I,and STCA-S,and STCA-M under different vehicle densities.The numerical simulation results show that our proposed STCA-L provides themost flexible lane changing guidance in the multi-lanes road.Moreover,the simulated results show that the exponential growth of physical space cannot provide the corresponding increase in the average flow of vehicles.
文摘Purpose–Freeway work zones have been traffic bottlenecks that lead to a series of problems,including long travel time,high-speed variation,driver’s dissatisfaction and traffic congestion.This research aims to develop a collaborative component of connected and automated vehicles(CAVs)to alleviate negative effects caused by work zones.Design/methodology/approach–The proposed cooperative component is incorporated in a cellular automata model to examine how and to what scale CAVs can help in improving traffic operations.Findings–Simulation results show that,with the proposed component and penetration of CAVs,the average performances(travel time,safety and emission)can all be improved and the stochasticity of performances will be minimized too.Originality/value–To the best of the authors’knowledge,this is the first research that develops a cooperative mechanism of CAVs to improve work zone performance.
基金sponsored by the Florida Department of Transportation(FDOT)and conducted as a cooperative effort by the Florida International University(FIU)and University of North Florida(UNF).
文摘This study evaluated the operational performance of Transit Signal Priority(TSP)using a microscopic simulation approach.The analysis was based on a 10-mile study corridor in South Florida.Two microscopic VISSIM simulation models were developed:a Base model,calibrated and validated to represent field conditions,and a TSP model.With TSP,the study corridor experienced up to 8%reduction in travel times and up to 13.3% reduction in average vehicle delay time,for both buses and all other vehicles.To better quantify the mobility benefits of the TSP strategy,Mobility Enhancement Factors(MEFs)were developed,unlike previous studies.A MEF is a multiplicative factor to estimate the expected mobility level after implementing TSP at a specific site.A MEF<1 implies that the TSP yields mobility benefits.TSP’s impact on cross-streets were also estimated.The study results indicate TSP strategy has enhanced mobility for buses and all other vehicles.
