The macroscopic fundamental diagram( MFD) is studied to obtain the aggregate behavior of traffic in cities. This paper investigates the existence and the characteristics of different types of daily MFD for the Shang...The macroscopic fundamental diagram( MFD) is studied to obtain the aggregate behavior of traffic in cities. This paper investigates the existence and the characteristics of different types of daily MFD for the Shanghai urban expressway network. The existence of MFD in the Shanghai urban expressway network is proved based on two weeks' data.Moreover, the hysteresis phenomena is present in most days and the network exhibits different hysteresis loops under different traffic situations. The relationship between the hysteresis phenomena and the inhomogeneity of traffic distribution is verified. The MFDs in the years of 2009 and 2012 are compared. The hysteresis loop still exists in 2012, which further verifies the existence of the hysteresis phenomenon. The direct relationship between the length of the hysteresis loop( ΔO) and the congestion is proved based on sufficient data. The width of the hysteresis loop, i. e., the drop in network flow( ΔQ) has no relationship with the congestion, and it varies from day to day under different traffic situations.展开更多
Pedestrian's road-crossing model is the key part of micro-simulation for mixed traffic at signalized intersection.To reproduce the crossing behavior of pedestrians,the microscopic behaviors of the pedestrians pass...Pedestrian's road-crossing model is the key part of micro-simulation for mixed traffic at signalized intersection.To reproduce the crossing behavior of pedestrians,the microscopic behaviors of the pedestrians passing through the crosswalk at signalized intersection were analyzed.A pedestrian's decision making model based on gap acceptance theory was proposed.Based on the field data at three typical intersections in Beijing,China,the critical gaps and lags of pedestrians were calibrated.In addition,considering pedestrian's required space,a modification of the social force model that consists of a self-deceleration mechanism prevents a simulated pedestrian from continuously pushing over other pedestrians,making the simulation more realistic.After the simple change,the modified social force model is able to reproduce the fundamental diagram of pedestrian flows for densities less than 3.5 m-2 as reported in the literature.展开更多
To investigate drivers' lane-changing behavior under different information feedback strategies,a microscopic traffic simulation based on the cellular automaton model was made on the typical freeway with a regular ...To investigate drivers' lane-changing behavior under different information feedback strategies,a microscopic traffic simulation based on the cellular automaton model was made on the typical freeway with a regular lane and a high-occupancy one. A new dynamic tolling scheme in terms of the real-time traffic condition on the high-occupancy lane was further designed to enhance the whole freeway's flow throughput. The results show that the mean velocity feedback strategy is generally more efficient than the travel time feedback strategy in correctly guiding drivers' lane choice behavior. Specifically,the toll level,lane-changing rate and freeway's throughput and congestion coefficient induced by the travel time feedback strategy oscillate with larger amplitude and longer period. In addition,the dynamic tolling scheme can make the high-occupancy lane less congested and maximize the freeway's throughput when the regular-lane inflow rate is larger than 0.45.展开更多
The paper presents the possibilities of implementing micro-simulation traffic tools in order to develop the evacuation plans. Well elaborated evacuation plans are the basis for alleviating the consequences resulting f...The paper presents the possibilities of implementing micro-simulation traffic tools in order to develop the evacuation plans. Well elaborated evacuation plans are the basis for alleviating the consequences resulting from emergencies. The simulation tools allow the design and verification of various evacuation planning scenarios with minimisation of costs and time. The paper provides detailed presentation of the basic characteristics of microscopic simulation of traffic flows, as well as examples of their implementation worldwide. The characteristics of the software tools are described through an overview of the basic settings ofPTV VISSIM (Planung Transport Verkehrin Stadten--Simulations model) program as one of the most significant representatives of these tools. The necessity of implementing the traffic tools in evacuation results from the crucial role of traffic in reducing the consequences of emergencies. These tools allow also a detailed analysis of the output data in order to select a suitable solution. The concluding part of the paper presents an example of evacuation of the population through the Jankomir node as part of the European project "preparedness for evacuation in case of a nuclear accident". The evacuation was performed through three scenarios in circumstances of higher or lower transport demand.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
In real-life freeway transportation system, a few number of incident observation (very rare event) is available while there are large numbers of normal condition dataset. Most of researches on freeway incident detec...In real-life freeway transportation system, a few number of incident observation (very rare event) is available while there are large numbers of normal condition dataset. Most of researches on freeway incident detection have considered the incident detection problem as classification one. However, because of insufficiency of incident events, most of previous researches have utilized simulated incident events to develop freeway incident detection models. In order to overcome this drawback, this paper proposes a wavelet-based Hotelling 7a control chart for freeway incident detection, which integrates a wavelet transform into an abnormal detection method. Firstly, wavelet transform extracts useful features from noisy original traffic observations, leading to reduce the dimensionality of input vectors. Then, a Hotelling T2 control chart describes a decision boundary with only normal traffic observations with the selected features in the wavelet domain. Unlike the existing incident detection algorithms, which require lots of incident observations to construct incident detection models, the proposed approach can decide a decision boundary given only normal training observations. The proposed method is evaluated in comparison with California algorithm, Minnesota algorithm and conventional neural networks. The experimental results present that the proposed algorithm in this paper is a promising alternative for freeway automatic incident detections.展开更多
A disorder situation of traffic operation always appears in on-ramp junction area of urban freeway,because the operation action for vehicles presents the weaving condition,especially for different vehicle types.Based ...A disorder situation of traffic operation always appears in on-ramp junction area of urban freeway,because the operation action for vehicles presents the weaving condition,especially for different vehicle types.Based on the analysis on the cellular automata theory,and combining with on-site survey data,several key parameters were defined,namely,cellular length,cellular speed,cellular acceleration,updating time interval.In addition,cellular acceleration rule,cellular deceleration rule,random rule,lane-changing rule and other micro-simulation rules were set,and cellular automaton micro-simulation model was set up.Further-more,a micro-simulation module was developed for traffic operation actions of on-ramp junction with Matlab toolbox.Finally,a simulation experiment for traffic operation reliability was done with this micro-simulation module,and the situation of change for on-ramp junction area was obtained under the conditions of different mainline design speed,acceleration lane length,vehicle generation probability and lane-changing probability.The results show that operation reliability for on-ramp junction is determined by the parameters of the probability of vehicle generation and the length of acceleration lane,especially for on-ramp.展开更多
According to the statistics of cultivated land in Yantai area during the Reform and Opening-up over the past 20 years and with the detailed survey and changing data of land use during the recent live years, this paper...According to the statistics of cultivated land in Yantai area during the Reform and Opening-up over the past 20 years and with the detailed survey and changing data of land use during the recent live years, this paper reveals the basic characteristics of the resource utilization, the basic process of the changes, regional differences, and current direction of cultivated land In addition, this paper makes a preliminary research on the major driving factors and the influence mechanism for the changes in the cultivated land area. and reaches the following conclasions: (1) There was a trend of obvious fluctuant decrease in cultivated laud area during the past 20 years. The changes of cultivated land have undergone the process - slow decrease,steep decrease, slow decrease. And there were three peak periods of cultivated land loss around 1985. 1987-1996 and 1991-1993 respectively (2) The decreased cultivated land was mainly converted into land for industry and mining, residential area. and all kinds of traffic and orchards. The increase of cultivated land mainly came from exploitation and land and arrangement and reclamation of industry and mining land (3) The economic development. population growth and policy are the dominant macro-driving factors for the decrease of cultivated land area in Yantai. The obvious sudden changes during the change process of cultivated land acreage are relevant to the national macro.policies background The rapid decrease of cnltivated land area is synchronous with the overheated economic growth resulting from the direct investment in fixed assets. Spatial distribution of the decrease in cultivated land is congruous with the differences in speed and the scale of economic growth between the different regions of Yantai area. Furthermore. the decrease in cultivated land caused by population increase cannot be ignored.展开更多
Traffic simulation models have the potential to provide an objective, cost-effective and flexible approach to assessing system design, traffic operations and management strategies. In that regard, the calibration and ...Traffic simulation models have the potential to provide an objective, cost-effective and flexible approach to assessing system design, traffic operations and management strategies. In that regard, the calibration and validation of simulation model is crucial for appropriate decision making process. This paper presents an application of microscopic simulation model calibration and validation procedure for a multimodal urban traffic network. Model is developed by VISSIM and VISSIG software tools.展开更多
The construction of a barrier-free environment is an important measure that guarantees the safety,right-of-way,and interests of the disabled,the elderly,and other mobility disadvantaged groups.It is also an indispensa...The construction of a barrier-free environment is an important measure that guarantees the safety,right-of-way,and interests of the disabled,the elderly,and other mobility disadvantaged groups.It is also an indispensable part of the low-carbon urban transportation and a necessary way to protect the rights of mobility disadvantaged groups in green travel.In this paper,the researchers conducted life log surveys on the travels of 10 wheelchair users residing in Beijing with IoT Inspector,a self-developed,wheelchairmountable intelligent sensing device.Wheelchair users’travel preferences and reasons were then analyzed using the image and textual data from the surveys.Combined with a mapping workshop,a comparative analysis was performed on the bumpiness of sidewalk paving materials.The study found that wheelchair travelers’preferred non-motor lanes over sidewalks;substandard curb ramps,unleveled tree pools,limited access widths,and bumpy pavement were the main problems faced by wheelchair users in sidewalk accessibility.In addition,the study explores the inclusive needs and challenges of non-motorized right-of-way for new transportation means at urban planning and traffic management levels.Based on multi-sourced data,this paper discusses the possibility of assessing urban barrier-free environment and representing a narrative of the needs of mobility disadvantaged groups,so as to provide practical experience and technical support to the improvement strategies of adaptive roads.展开更多
In this paper, we develop a macro model for traffic flow with consideration of static bottleneck to explore the impacts of static bottleneck on traffic flow. The analytical and numerical results show that the proposed...In this paper, we develop a macro model for traffic flow with consideration of static bottleneck to explore the impacts of static bottleneck on traffic flow. The analytical and numerical results show that the proposed model can qualitatively describe the equilibrium flux, uniform flow and small perturbation under the action of a static bottleneck.展开更多
基金The National Natural Science Foundation of China(No.51238008)
文摘The macroscopic fundamental diagram( MFD) is studied to obtain the aggregate behavior of traffic in cities. This paper investigates the existence and the characteristics of different types of daily MFD for the Shanghai urban expressway network. The existence of MFD in the Shanghai urban expressway network is proved based on two weeks' data.Moreover, the hysteresis phenomena is present in most days and the network exhibits different hysteresis loops under different traffic situations. The relationship between the hysteresis phenomena and the inhomogeneity of traffic distribution is verified. The MFDs in the years of 2009 and 2012 are compared. The hysteresis loop still exists in 2012, which further verifies the existence of the hysteresis phenomenon. The direct relationship between the length of the hysteresis loop( ΔO) and the congestion is proved based on sufficient data. The width of the hysteresis loop, i. e., the drop in network flow( ΔQ) has no relationship with the congestion, and it varies from day to day under different traffic situations.
基金Project(70972041)supported by the National Natural Science Foundation of ChinaProject(20100009110010)supported by the PhD Programs Foundation of Ministry of Education of ChinaProject(2011YJS246)supported by Fundamental Research Funds for the Central Universities of China
文摘Pedestrian's road-crossing model is the key part of micro-simulation for mixed traffic at signalized intersection.To reproduce the crossing behavior of pedestrians,the microscopic behaviors of the pedestrians passing through the crosswalk at signalized intersection were analyzed.A pedestrian's decision making model based on gap acceptance theory was proposed.Based on the field data at three typical intersections in Beijing,China,the critical gaps and lags of pedestrians were calibrated.In addition,considering pedestrian's required space,a modification of the social force model that consists of a self-deceleration mechanism prevents a simulated pedestrian from continuously pushing over other pedestrians,making the simulation more realistic.After the simple change,the modified social force model is able to reproduce the fundamental diagram of pedestrian flows for densities less than 3.5 m-2 as reported in the literature.
基金Project(70521001) supported by the National Natural Science Foundation of ChinaProject(2006CB705503) supported by the National Basic Research Program of ChinaProject supported by the Innovation Foundation of BUAA for PhD Graduates
文摘To investigate drivers' lane-changing behavior under different information feedback strategies,a microscopic traffic simulation based on the cellular automaton model was made on the typical freeway with a regular lane and a high-occupancy one. A new dynamic tolling scheme in terms of the real-time traffic condition on the high-occupancy lane was further designed to enhance the whole freeway's flow throughput. The results show that the mean velocity feedback strategy is generally more efficient than the travel time feedback strategy in correctly guiding drivers' lane choice behavior. Specifically,the toll level,lane-changing rate and freeway's throughput and congestion coefficient induced by the travel time feedback strategy oscillate with larger amplitude and longer period. In addition,the dynamic tolling scheme can make the high-occupancy lane less congested and maximize the freeway's throughput when the regular-lane inflow rate is larger than 0.45.
文摘The paper presents the possibilities of implementing micro-simulation traffic tools in order to develop the evacuation plans. Well elaborated evacuation plans are the basis for alleviating the consequences resulting from emergencies. The simulation tools allow the design and verification of various evacuation planning scenarios with minimisation of costs and time. The paper provides detailed presentation of the basic characteristics of microscopic simulation of traffic flows, as well as examples of their implementation worldwide. The characteristics of the software tools are described through an overview of the basic settings ofPTV VISSIM (Planung Transport Verkehrin Stadten--Simulations model) program as one of the most significant representatives of these tools. The necessity of implementing the traffic tools in evacuation results from the crucial role of traffic in reducing the consequences of emergencies. These tools allow also a detailed analysis of the output data in order to select a suitable solution. The concluding part of the paper presents an example of evacuation of the population through the Jankomir node as part of the European project "preparedness for evacuation in case of a nuclear accident". The evacuation was performed through three scenarios in circumstances of higher or lower transport demand.
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.
文摘In real-life freeway transportation system, a few number of incident observation (very rare event) is available while there are large numbers of normal condition dataset. Most of researches on freeway incident detection have considered the incident detection problem as classification one. However, because of insufficiency of incident events, most of previous researches have utilized simulated incident events to develop freeway incident detection models. In order to overcome this drawback, this paper proposes a wavelet-based Hotelling 7a control chart for freeway incident detection, which integrates a wavelet transform into an abnormal detection method. Firstly, wavelet transform extracts useful features from noisy original traffic observations, leading to reduce the dimensionality of input vectors. Then, a Hotelling T2 control chart describes a decision boundary with only normal traffic observations with the selected features in the wavelet domain. Unlike the existing incident detection algorithms, which require lots of incident observations to construct incident detection models, the proposed approach can decide a decision boundary given only normal training observations. The proposed method is evaluated in comparison with California algorithm, Minnesota algorithm and conventional neural networks. The experimental results present that the proposed algorithm in this paper is a promising alternative for freeway automatic incident detections.
基金Project(HIT.NSRIF.2009102) supported by the Fundamental Research Funds for the Central Universities in ChinaProject(11541295) supported by the Scientific Research Fund of Heilongjiang Provincial Education Department of ChinaProject(20100471029) supported by China Postdoctoral Science Foundation
文摘A disorder situation of traffic operation always appears in on-ramp junction area of urban freeway,because the operation action for vehicles presents the weaving condition,especially for different vehicle types.Based on the analysis on the cellular automata theory,and combining with on-site survey data,several key parameters were defined,namely,cellular length,cellular speed,cellular acceleration,updating time interval.In addition,cellular acceleration rule,cellular deceleration rule,random rule,lane-changing rule and other micro-simulation rules were set,and cellular automaton micro-simulation model was set up.Further-more,a micro-simulation module was developed for traffic operation actions of on-ramp junction with Matlab toolbox.Finally,a simulation experiment for traffic operation reliability was done with this micro-simulation module,and the situation of change for on-ramp junction area was obtained under the conditions of different mainline design speed,acceleration lane length,vehicle generation probability and lane-changing probability.The results show that operation reliability for on-ramp junction is determined by the parameters of the probability of vehicle generation and the length of acceleration lane,especially for on-ramp.
基金Supported by National Natural Science Foundation of China (40101005), Natural Science Foundation of Shandong Province (Q2002E03), and Education Department Foundation of ShandongProvince (J02L01).
文摘According to the statistics of cultivated land in Yantai area during the Reform and Opening-up over the past 20 years and with the detailed survey and changing data of land use during the recent live years, this paper reveals the basic characteristics of the resource utilization, the basic process of the changes, regional differences, and current direction of cultivated land In addition, this paper makes a preliminary research on the major driving factors and the influence mechanism for the changes in the cultivated land area. and reaches the following conclasions: (1) There was a trend of obvious fluctuant decrease in cultivated laud area during the past 20 years. The changes of cultivated land have undergone the process - slow decrease,steep decrease, slow decrease. And there were three peak periods of cultivated land loss around 1985. 1987-1996 and 1991-1993 respectively (2) The decreased cultivated land was mainly converted into land for industry and mining, residential area. and all kinds of traffic and orchards. The increase of cultivated land mainly came from exploitation and land and arrangement and reclamation of industry and mining land (3) The economic development. population growth and policy are the dominant macro-driving factors for the decrease of cultivated land area in Yantai. The obvious sudden changes during the change process of cultivated land acreage are relevant to the national macro.policies background The rapid decrease of cnltivated land area is synchronous with the overheated economic growth resulting from the direct investment in fixed assets. Spatial distribution of the decrease in cultivated land is congruous with the differences in speed and the scale of economic growth between the different regions of Yantai area. Furthermore. the decrease in cultivated land caused by population increase cannot be ignored.
文摘Traffic simulation models have the potential to provide an objective, cost-effective and flexible approach to assessing system design, traffic operations and management strategies. In that regard, the calibration and validation of simulation model is crucial for appropriate decision making process. This paper presents an application of microscopic simulation model calibration and validation procedure for a multimodal urban traffic network. Model is developed by VISSIM and VISSIG software tools.
文摘The construction of a barrier-free environment is an important measure that guarantees the safety,right-of-way,and interests of the disabled,the elderly,and other mobility disadvantaged groups.It is also an indispensable part of the low-carbon urban transportation and a necessary way to protect the rights of mobility disadvantaged groups in green travel.In this paper,the researchers conducted life log surveys on the travels of 10 wheelchair users residing in Beijing with IoT Inspector,a self-developed,wheelchairmountable intelligent sensing device.Wheelchair users’travel preferences and reasons were then analyzed using the image and textual data from the surveys.Combined with a mapping workshop,a comparative analysis was performed on the bumpiness of sidewalk paving materials.The study found that wheelchair travelers’preferred non-motor lanes over sidewalks;substandard curb ramps,unleveled tree pools,limited access widths,and bumpy pavement were the main problems faced by wheelchair users in sidewalk accessibility.In addition,the study explores the inclusive needs and challenges of non-motorized right-of-way for new transportation means at urban planning and traffic management levels.Based on multi-sourced data,this paper discusses the possibility of assessing urban barrier-free environment and representing a narrative of the needs of mobility disadvantaged groups,so as to provide practical experience and technical support to the improvement strategies of adaptive roads.
基金Supported by the Program for the New Century Excellent Talents in University under Grant No.NCET-08-0038the National Natural Science Foundation of China under Grant No.70971007the WA Centre of Excellence in Industrial Optimization
文摘In this paper, we develop a macro model for traffic flow with consideration of static bottleneck to explore the impacts of static bottleneck on traffic flow. The analytical and numerical results show that the proposed model can qualitatively describe the equilibrium flux, uniform flow and small perturbation under the action of a static bottleneck.