The rapid development of multimodal transportation system prompts travellers to choose multiple transportation modes, such as private vehicles or taxi, transit(subways or buses), or park-and-ride combinations for urba...The rapid development of multimodal transportation system prompts travellers to choose multiple transportation modes, such as private vehicles or taxi, transit(subways or buses), or park-and-ride combinations for urban trips. Traffic corridor is a major scenario that supports travellers to commute from suburban residential areas to central working areas. Studying their modal choice behaviour is receiving more and more interests. On one hand, it will guide the travellers to rationally choose their most economic and beneficial mode for urban trips. On the other hand, it will help traffic operators to make more appropriate policies to enhance the share of public transit in order to alleviate the traffic congestion and produce more economic and social benefits. To analyze the travel modal choice, a generalized cost model for three typical modes is first established to evaluate each different travel alternative. Then, random utility theory(RUT) and decision field theory(DFT) are introduced to describe the decision-making process how travellers make their mode choices. Further, some important factors that may influence the modal choice behaviour are discussed as well. To test the feasibility of the proposed model, a field test in Beijing was conducted to collect the real-time data and estimate the model parameters. The improvements in the test results and analysis show new advances in the development of travel mode choice on multimodal transportation networks.展开更多
The problem of designing integration traffic strategies for traffic corridors with the use of ramp metering, speed limit, and route guidance is considered in this paper. As an improvement to the previous work, the pre...The problem of designing integration traffic strategies for traffic corridors with the use of ramp metering, speed limit, and route guidance is considered in this paper. As an improvement to the previous work, the presented approach has the following five features： 1） modeling traffic flow to analyze traffic characteristics under the influence of variable speed limit, on-ramp metering and guidance information; 2） building a hierarchy model to realize the integration design of traffic control and route guidance in traffic corridors; 3） devising a multi-class analytical dynamic traffic assignment （DTA） model for traffic corridors, where not only the route choice process will be different for each user-class, but also the traffic flow operations are user-class specific because the travel time characteristic for each user-class is considered; 4） predicting route choice probabilities adaptively with real-time traffic conditions and route choice behaviors corresponding to variant users, rather than assuming as pre-determined; and 5） suggesting a numerical solution algorithm of the hierarchy model presented in this paper based on the modified algorithm of iterative optimization assignment （IOA）. Preliminary numerical test demonstrates the potential of the developed model and algorithm for integration corridor control.展开更多
With rapid development of air transportation,the airspace structure of the future will need to be flexible and dynamic to accommodate the increase in traffic demand.The corridors-in-the-sky has become a new technology...With rapid development of air transportation,the airspace structure of the future will need to be flexible and dynamic to accommodate the increase in traffic demand.The corridors-in-the-sky has become a new technology to support the full exploitation and utilization of airspace resources.This paper proposes a method of designing corridor,identifying congestion state,and analyzing the influence of air routes’traffic flow.From this,we have reached a number of conclusions.(1)The congestion periods present the multi-peak"wavy"scattered distributions and the peaks back-end agglomeration characteristics in the whole day.(2)The congestion segments present the structural characteristics of unbalanced coverage and concentrated distribution to the crossing points.The corridors with high congestion level present as an italic"N-shaped"frame,which presents incomplete penetration of short segments.(3)For the temporal and spatial interaction,there are two types of congestion segments,and there are some common congestion periods in different congestion segments of multiple corridors.The high-density air route plays a relatively decisive role in corridor congestion,and the influence of two directions is unbalanced.This research can provide a basis for the dynamic evaluation of China’s airspace resources and corridors construction in the future.展开更多
Traffic control and management are effective measures to solve the problem of traffic congestion. The optimal control model for freeway corridor is developed under incident conditions, which is in the form of minimiza...Traffic control and management are effective measures to solve the problem of traffic congestion. The optimal control model for freeway corridor is developed under incident conditions, which is in the form of minimization of the sum of the square of the difference between traffic demand and capacity at each intersection and on the freeway bottleneck section. The model optimizes control parameters of phase splits at arterial intersections, off-ramp diversion rates at upstream off-ramps and on-ramp diversion rates at downstream on ramps. Finally, the objective function is discussed and it is showed that the optimal control model is simple and practical.展开更多
Flow corridors are a new class of trajectory-based airspace which derives from the next generation air transportation system concept of operations. Reducing the airspace complexity and increasing the capacity are the ...Flow corridors are a new class of trajectory-based airspace which derives from the next generation air transportation system concept of operations. Reducing the airspace complexity and increasing the capacity are the main purposes of the en-route corridor. This paper analyzes the collision risk-capacity tradeoff using a combined discrete-continuous simulation method. A basic two-dimensional en-route flow corridor with performance rules is designed as the operational envi- ronment. A second-order system is established by combining the point mass model and the propor- tional derivative controller together to simulate the self-separation operations of the aircrafts in the corridor and the operation performance parameters from the User Manual for the Base of Aircraft Data are used in this research in order to improve the reliability. Simulation results indicate that the aircrafts can self-separate from each other efficiently by adjusting their velocities, and rationally set- ting the values of some variables can improve the rate and stability of the corridor with low risks of loss of separation.展开更多
基金Project(2012CB725405)supported in part by National Basic Research Program of ChinaProject(2014BAG03B01)supported by the National Science and Technology Support Program,China+1 种基金Project(71301083)supported by the National Natural Science Foundation of ChinaProject(20131089307)supported by the Project Supported by Tsinghua University,China
文摘The rapid development of multimodal transportation system prompts travellers to choose multiple transportation modes, such as private vehicles or taxi, transit(subways or buses), or park-and-ride combinations for urban trips. Traffic corridor is a major scenario that supports travellers to commute from suburban residential areas to central working areas. Studying their modal choice behaviour is receiving more and more interests. On one hand, it will guide the travellers to rationally choose their most economic and beneficial mode for urban trips. On the other hand, it will help traffic operators to make more appropriate policies to enhance the share of public transit in order to alleviate the traffic congestion and produce more economic and social benefits. To analyze the travel modal choice, a generalized cost model for three typical modes is first established to evaluate each different travel alternative. Then, random utility theory(RUT) and decision field theory(DFT) are introduced to describe the decision-making process how travellers make their mode choices. Further, some important factors that may influence the modal choice behaviour are discussed as well. To test the feasibility of the proposed model, a field test in Beijing was conducted to collect the real-time data and estimate the model parameters. The improvements in the test results and analysis show new advances in the development of travel mode choice on multimodal transportation networks.
基金supported by the National Natural Science Foundation of China (No.50808025)the Ministry of Communications of China Application Foundation (No.2006319815080)+1 种基金the Key Project of Hunan Education Department (No.08A003)the Project of Hunan Science and Technology Department (No.2008GK3114)
文摘The problem of designing integration traffic strategies for traffic corridors with the use of ramp metering, speed limit, and route guidance is considered in this paper. As an improvement to the previous work, the presented approach has the following five features： 1） modeling traffic flow to analyze traffic characteristics under the influence of variable speed limit, on-ramp metering and guidance information; 2） building a hierarchy model to realize the integration design of traffic control and route guidance in traffic corridors; 3） devising a multi-class analytical dynamic traffic assignment （DTA） model for traffic corridors, where not only the route choice process will be different for each user-class, but also the traffic flow operations are user-class specific because the travel time characteristic for each user-class is considered; 4） predicting route choice probabilities adaptively with real-time traffic conditions and route choice behaviors corresponding to variant users, rather than assuming as pre-determined; and 5） suggesting a numerical solution algorithm of the hierarchy model presented in this paper based on the modified algorithm of iterative optimization assignment （IOA）. Preliminary numerical test demonstrates the potential of the developed model and algorithm for integration corridor control.
基金National Natural Science Foundation of China,No.41671121
文摘With rapid development of air transportation,the airspace structure of the future will need to be flexible and dynamic to accommodate the increase in traffic demand.The corridors-in-the-sky has become a new technology to support the full exploitation and utilization of airspace resources.This paper proposes a method of designing corridor,identifying congestion state,and analyzing the influence of air routes’traffic flow.From this,we have reached a number of conclusions.(1)The congestion periods present the multi-peak"wavy"scattered distributions and the peaks back-end agglomeration characteristics in the whole day.(2)The congestion segments present the structural characteristics of unbalanced coverage and concentrated distribution to the crossing points.The corridors with high congestion level present as an italic"N-shaped"frame,which presents incomplete penetration of short segments.(3)For the temporal and spatial interaction,there are two types of congestion segments,and there are some common congestion periods in different congestion segments of multiple corridors.The high-density air route plays a relatively decisive role in corridor congestion,and the influence of two directions is unbalanced.This research can provide a basis for the dynamic evaluation of China’s airspace resources and corridors construction in the future.
基金This work was supported by the national 863 project of China (No. 2004AA505560).
文摘Traffic control and management are effective measures to solve the problem of traffic congestion. The optimal control model for freeway corridor is developed under incident conditions, which is in the form of minimization of the sum of the square of the difference between traffic demand and capacity at each intersection and on the freeway bottleneck section. The model optimizes control parameters of phase splits at arterial intersections, off-ramp diversion rates at upstream off-ramps and on-ramp diversion rates at downstream on ramps. Finally, the objective function is discussed and it is showed that the optimal control model is simple and practical.
基金supported by the National Natural Science Foundation of China (No.61104159)National Science and Technology Support Project (2011BAH24B08)the National Hightech Research and Development Program of China(No.2011BAH24B08)
文摘Flow corridors are a new class of trajectory-based airspace which derives from the next generation air transportation system concept of operations. Reducing the airspace complexity and increasing the capacity are the main purposes of the en-route corridor. This paper analyzes the collision risk-capacity tradeoff using a combined discrete-continuous simulation method. A basic two-dimensional en-route flow corridor with performance rules is designed as the operational envi- ronment. A second-order system is established by combining the point mass model and the propor- tional derivative controller together to simulate the self-separation operations of the aircrafts in the corridor and the operation performance parameters from the User Manual for the Base of Aircraft Data are used in this research in order to improve the reliability. Simulation results indicate that the aircrafts can self-separate from each other efficiently by adjusting their velocities, and rationally set- ting the values of some variables can improve the rate and stability of the corridor with low risks of loss of separation.
