Air traffic complexity is a critical indicator for air traffic operation,and plays an important role in air traffic management(ATM),such as airspace reconfiguration,air traffic flow management and allocation of air tr...Air traffic complexity is a critical indicator for air traffic operation,and plays an important role in air traffic management(ATM),such as airspace reconfiguration,air traffic flow management and allocation of air traffic controllers(ATCos).Recently,many machine learning techniques have been used to evaluate air traffic complexity by constructing a mapping from complexity related factors to air traffic complexity labels.However,the low quality of complexity labels,which is named as label noise,has often been neglected and caused unsatisfactory performance in air traffic complexity evaluation.This paper aims at label noise in air traffic complexity samples,and proposes a confident learning and XGBoost-based approach to evaluate air traffic complexity under label noise.The confident learning process is applied to filter out noisy samples with various label probability distributions,and XGBoost is used to train a robust and high-performance air traffic complexity evaluation model on the different label noise filtered ratio datasets.Experiments are carried out on a real dataset from the Guangzhou airspace sector in China,and the results prove that the appropriate label noise removal strategy and XGBoost algorithm can effectively mitigate the label noise problem and achieve better performance in air traffic complexity evaluation.展开更多
Occurrence degree of the accident on Zhejiang freeway is graded. Evaluation indicator system of weather impact on freeway is established. We use principal component analysis to extract meteorological indicators,and us...Occurrence degree of the accident on Zhejiang freeway is graded. Evaluation indicator system of weather impact on freeway is established. We use principal component analysis to extract meteorological indicators,and use Logistic regression to establish evaluation model of meteorological indicator,thereby determining evaluation grade of traffic weather impact. Via application test,it is proved that the evaluation on traffic weather condition by the model corresponds with actual situation,which can provide certain decision-making basis for traffic department and the public.展开更多
This paper presents an analysis of the random fluctuations, deferred conduction effect and periodicity of road traffic based on the basic features of road networks. It also discusses the limitations of road network ev...This paper presents an analysis of the random fluctuations, deferred conduction effect and periodicity of road traffic based on the basic features of road networks. It also discusses the limitations of road network evaluation theories based on road "V/C". In addition, it proposes a set of theoretical and technical methods for the real-time evaluation of traffic flows for entire road networks, and for solving key technical issues, such as real-time data collection and processing in areas with no blind zones, the spatial-temporal dynamic analysis of road network traffic, and the calibration of key performance index thresholds. It also provides new technical tools for the strategic transportation planning and real-time diagnosis of road traffic. The new tools and methodology presented in this paper are validated using a case study in Beijing.展开更多
The article is research on the traffic situations of freeways. Different rules make different traffic situations. It is meaningful to research on traffic situations under different conditions. The author analyzes fac...The article is research on the traffic situations of freeways. Different rules make different traffic situations. It is meaningful to research on traffic situations under different conditions. The author analyzes factors like traffic flow and safety, peflbrmance respectively, and proposes the theor3, basis for making more reasonable rules. The author first establishes evaluation system of traffic safety. Then, we compare the freeway network to power network to find a solution. and establish a traffic flow model based on power flow （TFPF）. It calculates power flow. So it applies the formula mode back to the traffic network, chalking up the perforumnce of the traffic condition. We utilize cellular automata （CA） method to simulate traffic circulation, and verify the accuracy of above model with the obtained data.展开更多
Signal retiming is a prominent way that transportation agencies use to fight congestion and change of traffic pattern.Performance evaluations of traffic conditions at signalized intersections and arterials provide act...Signal retiming is a prominent way that transportation agencies use to fight congestion and change of traffic pattern.Performance evaluations of traffic conditions at signalized intersections and arterials provide actionable data for agencies to make well-informed and prioritized signal retiming decisions.However,the abundance of data sources,the lack of standardized evaluation methods and oftentimes the shortage of resources make it a difficult endeavor.The review detailed in this paper examines the advances made in traffic signal performance evaluation.We establish the necessity for the evaluations,study the process of continuous improvement of traffic signal performance using the evaluations,and then examine multiple methodologies in a plethora of research endeavors.Particularly,we focus on probe vehicles and sensors data,the two major sources of data.We discuss how sensors are connected to signal controllers to provide relevant in-depth traffic data including speed and occupancy measures.We also review the nature of probe vehicles and the level of penetration.We then define and summarize performance measures derived from both sources,to aid in performance evaluations.For performance evaluation methods,we discuss the research studies and provide summaries including advantages and disadvantages of the methods used,as well as a holistic outlook for future research.This paper is aimed to provide a comprehensive review on the state-of-the-art to benefit researcher,traffic agencies,and commercial entities that thrive to improve safety and efficiency of traffic signals through performance evaluations.展开更多
As an important component of city evolution, urban land redevelopment has an impact on transportation system. The current traffic impact analysis （TIA） is lack of a comprehensive component for non-motorized transpor...As an important component of city evolution, urban land redevelopment has an impact on transportation system. The current traffic impact analysis （TIA） is lack of a comprehensive component for non-motorized transportation under redevelopment. For a better guidance of land redevelopment and non-motorized transportation planning, it is necessary to evaluate the negative impact of redevelopment on non-motorized traffic in the TIA. In this paper, an evaluation framework for the impact analysis is built up. We organized the pro- cedures and components of impact evaluation, and proposed the corresponding qualitative and quantitative evaluation indicators for non-motorized traffic under redevelopment. Level of service （LOS） and its criterion are employed for external impact evaluation, and level of safety, convenience, independence, and comfort which are four aspects of quality of service （QOS） are proposed to analyze the internal impact. The framework is applied to a redevelopment study in Shanghai, China. The case study results indicate that the rede- velopment from a residential area to a mixed commercial area has a significant impact on non-motorized traffic. The potential negative impact from both external and internal traffic can be minimized by reasonable improvements in the internal land use design.展开更多
To improve the traffic safety of electric two-wheelers(ETW),China has promulgated ETW standardization policies.This policy requires local governments to take measures to guide the illegal ETWs out of use.Governments h...To improve the traffic safety of electric two-wheelers(ETW),China has promulgated ETW standardization policies.This policy requires local governments to take measures to guide the illegal ETWs out of use.Governments have implemented a depreciation subsidy scheme to encourage users to scrap illegal ETWs early.When designing the subsidy scheme,effectively improving the ETWs’traffic safety at the road network level while saving government expenses is essential for the sustainable implementation of the policy.This study proposes an optimization method for depreciation subsidy design incorporating traffic safety evaluation.Based on the policy scheme,this study formulates a risk assessment model for the ETW traffic network to characterize the effect of the subsidy on improving safety.Then,we use the bi-level programming approach to model the subsidy strategy design problem.The upper-level problem reflects the goal of policymakers to maximize safety improvement and minimize government expenses.The lower-level problem describes the route choices of ETW users.The optimal subsidy design under different safety-expense trade-offs is analysed based on the Nguyen and Dupuis network and a real network extracted from Changsha City in China.The results show that specific subsidy schemes effectively improve road safety without a large government spending.When themarket price or service life of ETWs increases,the government spending on the same safety goal increases.The government should comprehensively consider the safety effect of financial expense and the situation of the local ETW market before selecting reasonable subsidy strategies.展开更多
基金This work was supported by the Na⁃tional Natural Science Foundation of China(No.61903187)Nanjing University of Aeronautics and Astronautics Graduate Innovation Base(Laboratory)Open Fund(No.kfjj20190732)。
文摘Air traffic complexity is a critical indicator for air traffic operation,and plays an important role in air traffic management(ATM),such as airspace reconfiguration,air traffic flow management and allocation of air traffic controllers(ATCos).Recently,many machine learning techniques have been used to evaluate air traffic complexity by constructing a mapping from complexity related factors to air traffic complexity labels.However,the low quality of complexity labels,which is named as label noise,has often been neglected and caused unsatisfactory performance in air traffic complexity evaluation.This paper aims at label noise in air traffic complexity samples,and proposes a confident learning and XGBoost-based approach to evaluate air traffic complexity under label noise.The confident learning process is applied to filter out noisy samples with various label probability distributions,and XGBoost is used to train a robust and high-performance air traffic complexity evaluation model on the different label noise filtered ratio datasets.Experiments are carried out on a real dataset from the Guangzhou airspace sector in China,and the results prove that the appropriate label noise removal strategy and XGBoost algorithm can effectively mitigate the label noise problem and achieve better performance in air traffic complexity evaluation.
基金Supported by the Science and Technology Plan Item of Zhejiang Province,China(2014C23003)
文摘Occurrence degree of the accident on Zhejiang freeway is graded. Evaluation indicator system of weather impact on freeway is established. We use principal component analysis to extract meteorological indicators,and use Logistic regression to establish evaluation model of meteorological indicator,thereby determining evaluation grade of traffic weather impact. Via application test,it is proved that the evaluation on traffic weather condition by the model corresponds with actual situation,which can provide certain decision-making basis for traffic department and the public.
基金"973"National Key Basic Research & Development Program "Research of the Basic Scientific Issues in the Traffic Congestion Bottlenecks of Big Cities"( No. 2006CB705500)Beijing Science & Technology Program "Research of the New Data Collection Technologies for Transportation Management " (No.D101100049710004)Beijing Science & Technology Program "Research of the Demonstration Platform for the In-tegrated Dynamic Operation Analysis of City Road Networks"(No. D07050600440704)
文摘This paper presents an analysis of the random fluctuations, deferred conduction effect and periodicity of road traffic based on the basic features of road networks. It also discusses the limitations of road network evaluation theories based on road "V/C". In addition, it proposes a set of theoretical and technical methods for the real-time evaluation of traffic flows for entire road networks, and for solving key technical issues, such as real-time data collection and processing in areas with no blind zones, the spatial-temporal dynamic analysis of road network traffic, and the calibration of key performance index thresholds. It also provides new technical tools for the strategic transportation planning and real-time diagnosis of road traffic. The new tools and methodology presented in this paper are validated using a case study in Beijing.
文摘The article is research on the traffic situations of freeways. Different rules make different traffic situations. It is meaningful to research on traffic situations under different conditions. The author analyzes factors like traffic flow and safety, peflbrmance respectively, and proposes the theor3, basis for making more reasonable rules. The author first establishes evaluation system of traffic safety. Then, we compare the freeway network to power network to find a solution. and establish a traffic flow model based on power flow （TFPF）. It calculates power flow. So it applies the formula mode back to the traffic network, chalking up the perforumnce of the traffic condition. We utilize cellular automata （CA） method to simulate traffic circulation, and verify the accuracy of above model with the obtained data.
基金supported in part by Tennessee Department of Transportation(TDOT)and Federal Highway Administration(FHWA),under TDOT grant RES2021-09
文摘Signal retiming is a prominent way that transportation agencies use to fight congestion and change of traffic pattern.Performance evaluations of traffic conditions at signalized intersections and arterials provide actionable data for agencies to make well-informed and prioritized signal retiming decisions.However,the abundance of data sources,the lack of standardized evaluation methods and oftentimes the shortage of resources make it a difficult endeavor.The review detailed in this paper examines the advances made in traffic signal performance evaluation.We establish the necessity for the evaluations,study the process of continuous improvement of traffic signal performance using the evaluations,and then examine multiple methodologies in a plethora of research endeavors.Particularly,we focus on probe vehicles and sensors data,the two major sources of data.We discuss how sensors are connected to signal controllers to provide relevant in-depth traffic data including speed and occupancy measures.We also review the nature of probe vehicles and the level of penetration.We then define and summarize performance measures derived from both sources,to aid in performance evaluations.For performance evaluation methods,we discuss the research studies and provide summaries including advantages and disadvantages of the methods used,as well as a holistic outlook for future research.This paper is aimed to provide a comprehensive review on the state-of-the-art to benefit researcher,traffic agencies,and commercial entities that thrive to improve safety and efficiency of traffic signals through performance evaluations.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education(No. 200802470030)
文摘As an important component of city evolution, urban land redevelopment has an impact on transportation system. The current traffic impact analysis （TIA） is lack of a comprehensive component for non-motorized transportation under redevelopment. For a better guidance of land redevelopment and non-motorized transportation planning, it is necessary to evaluate the negative impact of redevelopment on non-motorized traffic in the TIA. In this paper, an evaluation framework for the impact analysis is built up. We organized the pro- cedures and components of impact evaluation, and proposed the corresponding qualitative and quantitative evaluation indicators for non-motorized traffic under redevelopment. Level of service （LOS） and its criterion are employed for external impact evaluation, and level of safety, convenience, independence, and comfort which are four aspects of quality of service （QOS） are proposed to analyze the internal impact. The framework is applied to a redevelopment study in Shanghai, China. The case study results indicate that the rede- velopment from a residential area to a mixed commercial area has a significant impact on non-motorized traffic. The potential negative impact from both external and internal traffic can be minimized by reasonable improvements in the internal land use design.
基金National Natural Science Foundation of China(Grant No.71971222).
文摘To improve the traffic safety of electric two-wheelers(ETW),China has promulgated ETW standardization policies.This policy requires local governments to take measures to guide the illegal ETWs out of use.Governments have implemented a depreciation subsidy scheme to encourage users to scrap illegal ETWs early.When designing the subsidy scheme,effectively improving the ETWs’traffic safety at the road network level while saving government expenses is essential for the sustainable implementation of the policy.This study proposes an optimization method for depreciation subsidy design incorporating traffic safety evaluation.Based on the policy scheme,this study formulates a risk assessment model for the ETW traffic network to characterize the effect of the subsidy on improving safety.Then,we use the bi-level programming approach to model the subsidy strategy design problem.The upper-level problem reflects the goal of policymakers to maximize safety improvement and minimize government expenses.The lower-level problem describes the route choices of ETW users.The optimal subsidy design under different safety-expense trade-offs is analysed based on the Nguyen and Dupuis network and a real network extracted from Changsha City in China.The results show that specific subsidy schemes effectively improve road safety without a large government spending.When themarket price or service life of ETWs increases,the government spending on the same safety goal increases.The government should comprehensively consider the safety effect of financial expense and the situation of the local ETW market before selecting reasonable subsidy strategies.
