Traffic wave theory is used to study the critical conditions for traffic jams according to their features. First, the characteristics of traffic wave propagation is analyzed for the simple signal-controlled lane and t...Traffic wave theory is used to study the critical conditions for traffic jams according to their features. First, the characteristics of traffic wave propagation is analyzed for the simple signal-controlled lane and the critical conditions for oversaturation is established. Then, the basic road is decomposed into a series of one-way links according to its topological characteristics. Based on the decomposition, traffic wave propagation under complex conditions is studied. Three complicated factors are considered to establish the corresponding critical conditions of jam formation, namely, dynamic and insufficient split, channelized section spillover and endogenous traffic flow. The results show that road geometric features, traffic demand structures and signal settings influence the formation and propagation of traffic congestion. These findings can serve as a theoretical basis for future network jam control.展开更多
To alleviate the resulting increase in energy consumption and emissions and other issues caused by the traffic congestion ahead of the expressway toll station, a novel traffic flowcontrol method is put forward based o...To alleviate the resulting increase in energy consumption and emissions and other issues caused by the traffic congestion ahead of the expressway toll station, a novel traffic flowcontrol method is put forward based on the environment-friendly conception. The technical thinking of inducing the slowly moving traffic into a batch pass is determined based on the conclusion of the research, traffic flowtheory and traffic sensing detection technology. The model of stop times is established and the parameters of the system are optimized in accordance with the principle of minimizing the fuel consumption. The optimal location selection of traffic control lights and Detector 2 for queue of different lengths at toll stations are calculated based on the model. Finally, the effect of the congestion flowcontrol system is verified via the Paramics simulation system. The result shows that the control system is capable of reducing90% of fuel consumption for vehicles going through toll stations.展开更多
According to the distribution characteristics of traffic congestion in time and space, a measure index system of urban traffic congestion is set up based on the spatial and temporal distribution. Based on the analysis...According to the distribution characteristics of traffic congestion in time and space, a measure index system of urban traffic congestion is set up based on the spatial and temporal distribution. Based on the analysis of the main characteristics of traffic congestion and the generation process of traffic congestion, the measure model for urban traffic congestion is constructed by the value function. Moreover, based on the measure values of traffic congestion in urban road networks with defined different levels, a method to prevent and control traffic congestion is designed. The application results confirm that the proposed method is feasible in comprehensive measures for urban traffic congestion and they are consistent with the results of other methods. The measuring results can therefore reflect the actual situation. The comprehensive measure model is scientific and the process is simple, and it has wide application prospects and practical value.展开更多
Considering the decision-making variables of the capacities of branch roads and the optimization targets of lowering the saturation of arterial roads and the reconstruction expense of branch roads, the bi-level progra...Considering the decision-making variables of the capacities of branch roads and the optimization targets of lowering the saturation of arterial roads and the reconstruction expense of branch roads, the bi-level programming model for reconstructing the branch roads was set up. The upper level model was for determining the enlarged capacities of the branch roads, and the lower level model was for calculating the flows of road sections via the user equilibrium traffic assignment method. The genetic algorithm for solving the bi-level model was designed to obtain the reconstruction capacities of the branch roads. The results show that by the bi-level model and its algorithm, the optimum scheme of urban branch roads reconstruction can be gained, which reduces the saturation of arterial roads apparently, and alleviates traffic congestion. In the data analysis the arterial saturation decreases from 1.100 to 0.996, which verifies the micro-circulation transportation's function of urban branch road network.展开更多
Road side barriers are constructed to protect passengers and contain vehicles when a vehicle crashes into a barrier. In general, full-scale crash testing needs to be carried out if a geometrically and structurally equ...Road side barriers are constructed to protect passengers and contain vehicles when a vehicle crashes into a barrier. In general, full-scale crash testing needs to be carried out if a geometrically and structurally equivalent barrier has not previously been proven to meet the requirements of containing the vehicle and dissipating sufficient impact energy for passenger protection. As full-scale crash testing is very expensive, the number of data that can be measured in a test is usually limited, and it may not always be possible to obtain good quality measurements in such a test, a reliable and efficient numerical simulation of crash testing is therefore very useful. This paper presents finite element simulations of a 3-rail steel road traffic barrier under vehicle impact. The performance levels defined in Australian Standards AS5100 Clause 10.5 for these barriers are checked. The numerical simulations show that the barrier is able to meet low performance levels. However, the maximum deceleration is higher than the acceptable limit for passenger protection. If present, a kerb launches the vehicles into the barrier, allowing for the possibility of overriding the barrier under certain circumstances, but it redirects the vehicle and reduces the incident angle, which reduces impact force on the barrier. Further investigation into all common kerb profiles on roads should be carried out, as only one kerb profile is investigated in this study.展开更多
Traffic congestion is widely distributed around a network. Generally, to analyze traffic congestion, static traffic capacity is adopted. But dynamic characteristics must be studied because congestion is a dynamic proc...Traffic congestion is widely distributed around a network. Generally, to analyze traffic congestion, static traffic capacity is adopted. But dynamic characteristics must be studied because congestion is a dynamic process. A Dynamic Traffic Assignment modeling fundamental combined with an urban congestion analysis method is studied in this paper. Three methods are based on congestion analysis, and the stochastic user optimal DTA models are especially considered. Correspondingly, a dynamic system optimal model is suggested for responding congestion countermeasures and an ideal user optimal model for predicted congestion countermeasure respectively.展开更多
The expansion joints are expected to have movement capacity, bearing capacity for static and dynamic loading, water-tightness, low noise emission and traffic safety. In particular, the failure due to impact loading is...The expansion joints are expected to have movement capacity, bearing capacity for static and dynamic loading, water-tightness, low noise emission and traffic safety. In particular, the failure due to impact loading is the main reason for the observed damages. The problem of dynamic behavior of the expansion joints is so complex that we shall focus our attention on the impact factor for vehicle load that is governed by traffic impact. In order to overcome this difficulty, the cantilever-toothed aluminum joint (finger joint) is one of the promising joints under impact loading. In this study, from the viewpoint of design methodology, numerical studies for impact behavior were conducted for aluminum alloy expansion joints with perforated dowels. The design impact factor for the expansion joints with the perforated dowels against traffic impact loading was examined by using numerical simulations.展开更多
One-way traffic organization is a direct, efficient and economic method to solve traffic congestion and expand traffie capacity. With its evolution, advantages and disadvantages introduced its setting conditions demon...One-way traffic organization is a direct, efficient and economic method to solve traffic congestion and expand traffie capacity. With its evolution, advantages and disadvantages introduced its setting conditions demonstrated. The general method and processes are summarized in planning for urban one-way streets project, viz. investigation, drawing out and evaluation of project, selecting of project and beneficial analysis. Fuzzy synthetical evaluation other fields is employed to evaluate the project. Its evaluation system and method is introduced and Delphi method is adopted to obtain evaluation index. Finally, taking Harbin city as an example, the application process of above-mentioned method is illuminated. Accordingly, it is proved that the method is exercisable.展开更多
In order to alleviate urban traffic congestion and provide fast vehicle paths,a hidden Markov model(HMM)based on multi-feature data of urban regional roads is constructed to solve the problems of low recognition rate ...In order to alleviate urban traffic congestion and provide fast vehicle paths,a hidden Markov model(HMM)based on multi-feature data of urban regional roads is constructed to solve the problems of low recognition rate and poor instability of traditional model algorithms.At first,the HHM is obtained by training.Then according to dynamic planning principle,the traffic states of intersections are obtained by the Viterbi algorithm.Finally,the optimal path is selected based on the obtained traffic states of intersections.The experiment results show that the proposed method is superior to other algorithms in road unobstruction rate and recognition rate under complex road conditions.展开更多
The year of 2013 is considered the first year of smart city in China. With the development of informationization and urbanization in China, city diseases(traffic jam, medical problem and unbalanced education) are more...The year of 2013 is considered the first year of smart city in China. With the development of informationization and urbanization in China, city diseases(traffic jam, medical problem and unbalanced education) are more and more apparent. Smart city is the key to solving these diseases. This paper presents the overall smart city development in China in term of market scale and development stages, the technology standards, and industry layout. The paper claims that the issues and challenges facing smart city development in China and proposes to make polices to support smart city development.展开更多
Metropolitan cities in China are commonly confronted with unresolved traffic congestion issues, primarily due to rapidly increasing traffic demand. Group disparity between commuting mode choice and its spatial distrib...Metropolitan cities in China are commonly confronted with unresolved traffic congestion issues, primarily due to rapidly increasing traffic demand. Group disparity between commuting mode choice and its spatial distribution on road networks has enabled us to examine the factors that give rise to the discrepancies and the fundamental spatial causes of traffic congestion. In recent years, mi- cro-perspective, individual, and behavior-based spatial analysis have mushroomed and been facilitated with effective tools such as tem- poral geographic information systems (T-GIS). It is difficult to study the interrelations between transport and space on the basis of commuting mode choice since the mode choice data are invisible in a specific space such as a particular road network. Therefore, in the field of transport, the classical origin destination (OD) four-stage model (FSM) is usually employed to calculate data when studying commuting mode choice. Based on the relative principles of T-GIS and the platform of ArcGIS, this paper considers Guangzhou as a case study and develops a spatio-temporal tool to examine the daily activities of residents. Meanwhile, the traffic volume distribution in rush hours, which was analyzed according to commuting modes and how they were reflected in the road network, was scrutinized with data extracted from travel diaries. Moreover, efforts were made to explain the relationship between traffic demand and urban spatial structure. Based on the investigation, this research indicates that traffic volumes in divergent groups and on the road networks is driven by: l) the socio-economie characteristics of travelers; 2) a jobs-housing imbalance under suburbanization; 3) differences in the spatial supply of transport modes; 4) the remains of the Danwei (work unit) system and market development in China; and 5) the transition of urban spatial structure and other factors.展开更多
With the advancements in wireless sensor networks, Internet of Vehicles(IOV) has shown great potential in aiding to ease traffic congestion. In IOV, vehicles can easily exchange information with other vehicles and inf...With the advancements in wireless sensor networks, Internet of Vehicles(IOV) has shown great potential in aiding to ease traffic congestion. In IOV, vehicles can easily exchange information with other vehicles and infrastructures, thus, the development of IOV will greatly improve vehicles safety, promote green information consumption and have a profound impact on many industries. The purpose of this paper is to promote the innovation and development of IOV. Firstly, this paper presents general requirements of IOV such as guidelines, basic principles, and the goal of development. Secondly, we analyze critical applications, crucial support, and business model to promote the industrial development of IOV. Finally, this paper proposes some safeguard measures to further promote the development of IOV.展开更多
Based on the study on the city transport systems of some typical cities worldwide,this paper put forward that each city transport system has its own development mode,which is influenced by the city development plan,ec...Based on the study on the city transport systems of some typical cities worldwide,this paper put forward that each city transport system has its own development mode,which is influenced by the city development plan,economic development level,traveling vehicle composition etc..When some problems occur,such as the congestions caused by contradiction between the road capacity and vehicle composition,the city transport system may come into temporary maturity period.If the improvement for road system is limited meanwhile,optimized structure of vehicle composition should be an effective solution in this case.With the development of economy-internationalization,the development speed of city transport modernization is rapid.When traveling easiness is conflicting with efficiency,the advantages of public transport system become more obvious.Correspondingly,the superiority of two-wheel vehicles will reappear.Though the important function of two-wheel vehicles for alleviating city traffic problems is obvious,however,their development strategy must be reasonably proposed,and operation regulations must be performed accordingly.展开更多
Traffic congestion has caused many detrimental effects including higher fuel consumption, more vehicle emissions, increased accidents, as well as greater tension due to uncertain travel time. In addition to delay, the...Traffic congestion has caused many detrimental effects including higher fuel consumption, more vehicle emissions, increased accidents, as well as greater tension due to uncertain travel time. In addition to delay, the variability and reliability of travel time has been of concern to motorists on their daily travel, especially during peak periods. The objective of this study is to examine freeway travel time variability and reliability under different traffic and weather conditions with the use of TRANSMIT data collected by roadside readers deployed on a 40-mile segment of the Interstate Highway 1-287 in New Jersey. Travel time variability and reliability measures including mean travel time, the 95th percentile travel time, travel time index, buffer index, and planning time index under recurring and non-recurring congestion (adverse weather) are investigated. It was found that the standard deviation of travel time increased, due to the weather condition varying from dry to rain and to snow, while the buffer index increased from 29% to 45% and to 94%.展开更多
Traffic jam in large signalized road network presents a complex nature.In order to reveal the jam characteristics,two indexes,SVS(speed of virtual signal) and VOS(velocity of spillover),were proposed respectively.SVS ...Traffic jam in large signalized road network presents a complex nature.In order to reveal the jam characteristics,two indexes,SVS(speed of virtual signal) and VOS(velocity of spillover),were proposed respectively.SVS described the propagation of queue within a link while VOS reflected the spillover velocity of vehicle queue.Based on the two indexes,network jam simulation was carried out on a regular signalized road network.The simulation results show that:1) The propagation of traffic congestion on a signalized road network can be classified into two stages:virtual split driven stage and flow rate driven stage.The former stage is characterized by decreasing virtual split while the latter only depends on flow rate; 2) The jam propagation rate and direction are dependent on traffic demand distribution and other network parameters.The direction with higher demand gets more chance to be jammed.Our findings can serve as the basis of the prevention of the formation and propagation of network traffic jam.展开更多
基金The National Basic Research Program of China(973 Program)(No.2006CB705505)the Basic Scientific Research Fund of Jilin University(No.200903209)
文摘Traffic wave theory is used to study the critical conditions for traffic jams according to their features. First, the characteristics of traffic wave propagation is analyzed for the simple signal-controlled lane and the critical conditions for oversaturation is established. Then, the basic road is decomposed into a series of one-way links according to its topological characteristics. Based on the decomposition, traffic wave propagation under complex conditions is studied. Three complicated factors are considered to establish the corresponding critical conditions of jam formation, namely, dynamic and insufficient split, channelized section spillover and endogenous traffic flow. The results show that road geometric features, traffic demand structures and signal settings influence the formation and propagation of traffic congestion. These findings can serve as a theoretical basis for future network jam control.
基金The Natural Science Foundation of Hebei Province(No.E2013202228)the Science and Technology Planning Project of the Department of Transportation of Hebei Province(No.R070245)
文摘To alleviate the resulting increase in energy consumption and emissions and other issues caused by the traffic congestion ahead of the expressway toll station, a novel traffic flowcontrol method is put forward based on the environment-friendly conception. The technical thinking of inducing the slowly moving traffic into a batch pass is determined based on the conclusion of the research, traffic flowtheory and traffic sensing detection technology. The model of stop times is established and the parameters of the system are optimized in accordance with the principle of minimizing the fuel consumption. The optimal location selection of traffic control lights and Detector 2 for queue of different lengths at toll stations are calculated based on the model. Finally, the effect of the congestion flowcontrol system is verified via the Paramics simulation system. The result shows that the control system is capable of reducing90% of fuel consumption for vehicles going through toll stations.
基金The National Natural Science Foundation of China(No.51178157)
文摘According to the distribution characteristics of traffic congestion in time and space, a measure index system of urban traffic congestion is set up based on the spatial and temporal distribution. Based on the analysis of the main characteristics of traffic congestion and the generation process of traffic congestion, the measure model for urban traffic congestion is constructed by the value function. Moreover, based on the measure values of traffic congestion in urban road networks with defined different levels, a method to prevent and control traffic congestion is designed. The application results confirm that the proposed method is feasible in comprehensive measures for urban traffic congestion and they are consistent with the results of other methods. The measuring results can therefore reflect the actual situation. The comprehensive measure model is scientific and the process is simple, and it has wide application prospects and practical value.
基金Project(2006CB705507) supported by the National Basic Research and Development Program of ChinaProject(20060533036) supported by the Specialized Research Foundation for the Doctoral Program of Higher Education of China
文摘Considering the decision-making variables of the capacities of branch roads and the optimization targets of lowering the saturation of arterial roads and the reconstruction expense of branch roads, the bi-level programming model for reconstructing the branch roads was set up. The upper level model was for determining the enlarged capacities of the branch roads, and the lower level model was for calculating the flows of road sections via the user equilibrium traffic assignment method. The genetic algorithm for solving the bi-level model was designed to obtain the reconstruction capacities of the branch roads. The results show that by the bi-level model and its algorithm, the optimum scheme of urban branch roads reconstruction can be gained, which reduces the saturation of arterial roads apparently, and alleviates traffic congestion. In the data analysis the arterial saturation decreases from 1.100 to 0.996, which verifies the micro-circulation transportation's function of urban branch road network.
文摘Road side barriers are constructed to protect passengers and contain vehicles when a vehicle crashes into a barrier. In general, full-scale crash testing needs to be carried out if a geometrically and structurally equivalent barrier has not previously been proven to meet the requirements of containing the vehicle and dissipating sufficient impact energy for passenger protection. As full-scale crash testing is very expensive, the number of data that can be measured in a test is usually limited, and it may not always be possible to obtain good quality measurements in such a test, a reliable and efficient numerical simulation of crash testing is therefore very useful. This paper presents finite element simulations of a 3-rail steel road traffic barrier under vehicle impact. The performance levels defined in Australian Standards AS5100 Clause 10.5 for these barriers are checked. The numerical simulations show that the barrier is able to meet low performance levels. However, the maximum deceleration is higher than the acceptable limit for passenger protection. If present, a kerb launches the vehicles into the barrier, allowing for the possibility of overriding the barrier under certain circumstances, but it redirects the vehicle and reduces the incident angle, which reduces impact force on the barrier. Further investigation into all common kerb profiles on roads should be carried out, as only one kerb profile is investigated in this study.
文摘Traffic congestion is widely distributed around a network. Generally, to analyze traffic congestion, static traffic capacity is adopted. But dynamic characteristics must be studied because congestion is a dynamic process. A Dynamic Traffic Assignment modeling fundamental combined with an urban congestion analysis method is studied in this paper. Three methods are based on congestion analysis, and the stochastic user optimal DTA models are especially considered. Correspondingly, a dynamic system optimal model is suggested for responding congestion countermeasures and an ideal user optimal model for predicted congestion countermeasure respectively.
文摘The expansion joints are expected to have movement capacity, bearing capacity for static and dynamic loading, water-tightness, low noise emission and traffic safety. In particular, the failure due to impact loading is the main reason for the observed damages. The problem of dynamic behavior of the expansion joints is so complex that we shall focus our attention on the impact factor for vehicle load that is governed by traffic impact. In order to overcome this difficulty, the cantilever-toothed aluminum joint (finger joint) is one of the promising joints under impact loading. In this study, from the viewpoint of design methodology, numerical studies for impact behavior were conducted for aluminum alloy expansion joints with perforated dowels. The design impact factor for the expansion joints with the perforated dowels against traffic impact loading was examined by using numerical simulations.
基金Sponsored by the National Natural Science of China(Grant No. 50278026)
文摘One-way traffic organization is a direct, efficient and economic method to solve traffic congestion and expand traffie capacity. With its evolution, advantages and disadvantages introduced its setting conditions demonstrated. The general method and processes are summarized in planning for urban one-way streets project, viz. investigation, drawing out and evaluation of project, selecting of project and beneficial analysis. Fuzzy synthetical evaluation other fields is employed to evaluate the project. Its evaluation system and method is introduced and Delphi method is adopted to obtain evaluation index. Finally, taking Harbin city as an example, the application process of above-mentioned method is illuminated. Accordingly, it is proved that the method is exercisable.
基金Natural Science Foundation of Gansu Provincial Science&Technology Department(No.1504GKCA018)。
文摘In order to alleviate urban traffic congestion and provide fast vehicle paths,a hidden Markov model(HMM)based on multi-feature data of urban regional roads is constructed to solve the problems of low recognition rate and poor instability of traditional model algorithms.At first,the HHM is obtained by training.Then according to dynamic planning principle,the traffic states of intersections are obtained by the Viterbi algorithm.Finally,the optimal path is selected based on the obtained traffic states of intersections.The experiment results show that the proposed method is superior to other algorithms in road unobstruction rate and recognition rate under complex road conditions.
文摘The year of 2013 is considered the first year of smart city in China. With the development of informationization and urbanization in China, city diseases(traffic jam, medical problem and unbalanced education) are more and more apparent. Smart city is the key to solving these diseases. This paper presents the overall smart city development in China in term of market scale and development stages, the technology standards, and industry layout. The paper claims that the issues and challenges facing smart city development in China and proposes to make polices to support smart city development.
基金Under the auspices of National Natural Science Foundation of China(No.40971098)National High Technology Research and Development Program of China(No.2012AA121402)
文摘Metropolitan cities in China are commonly confronted with unresolved traffic congestion issues, primarily due to rapidly increasing traffic demand. Group disparity between commuting mode choice and its spatial distribution on road networks has enabled us to examine the factors that give rise to the discrepancies and the fundamental spatial causes of traffic congestion. In recent years, mi- cro-perspective, individual, and behavior-based spatial analysis have mushroomed and been facilitated with effective tools such as tem- poral geographic information systems (T-GIS). It is difficult to study the interrelations between transport and space on the basis of commuting mode choice since the mode choice data are invisible in a specific space such as a particular road network. Therefore, in the field of transport, the classical origin destination (OD) four-stage model (FSM) is usually employed to calculate data when studying commuting mode choice. Based on the relative principles of T-GIS and the platform of ArcGIS, this paper considers Guangzhou as a case study and develops a spatio-temporal tool to examine the daily activities of residents. Meanwhile, the traffic volume distribution in rush hours, which was analyzed according to commuting modes and how they were reflected in the road network, was scrutinized with data extracted from travel diaries. Moreover, efforts were made to explain the relationship between traffic demand and urban spatial structure. Based on the investigation, this research indicates that traffic volumes in divergent groups and on the road networks is driven by: l) the socio-economie characteristics of travelers; 2) a jobs-housing imbalance under suburbanization; 3) differences in the spatial supply of transport modes; 4) the remains of the Danwei (work unit) system and market development in China; and 5) the transition of urban spatial structure and other factors.
文摘With the advancements in wireless sensor networks, Internet of Vehicles(IOV) has shown great potential in aiding to ease traffic congestion. In IOV, vehicles can easily exchange information with other vehicles and infrastructures, thus, the development of IOV will greatly improve vehicles safety, promote green information consumption and have a profound impact on many industries. The purpose of this paper is to promote the innovation and development of IOV. Firstly, this paper presents general requirements of IOV such as guidelines, basic principles, and the goal of development. Secondly, we analyze critical applications, crucial support, and business model to promote the industrial development of IOV. Finally, this paper proposes some safeguard measures to further promote the development of IOV.
文摘Based on the study on the city transport systems of some typical cities worldwide,this paper put forward that each city transport system has its own development mode,which is influenced by the city development plan,economic development level,traveling vehicle composition etc..When some problems occur,such as the congestions caused by contradiction between the road capacity and vehicle composition,the city transport system may come into temporary maturity period.If the improvement for road system is limited meanwhile,optimized structure of vehicle composition should be an effective solution in this case.With the development of economy-internationalization,the development speed of city transport modernization is rapid.When traveling easiness is conflicting with efficiency,the advantages of public transport system become more obvious.Correspondingly,the superiority of two-wheel vehicles will reappear.Though the important function of two-wheel vehicles for alleviating city traffic problems is obvious,however,their development strategy must be reasonably proposed,and operation regulations must be performed accordingly.
文摘Traffic congestion has caused many detrimental effects including higher fuel consumption, more vehicle emissions, increased accidents, as well as greater tension due to uncertain travel time. In addition to delay, the variability and reliability of travel time has been of concern to motorists on their daily travel, especially during peak periods. The objective of this study is to examine freeway travel time variability and reliability under different traffic and weather conditions with the use of TRANSMIT data collected by roadside readers deployed on a 40-mile segment of the Interstate Highway 1-287 in New Jersey. Travel time variability and reliability measures including mean travel time, the 95th percentile travel time, travel time index, buffer index, and planning time index under recurring and non-recurring congestion (adverse weather) are investigated. It was found that the standard deviation of travel time increased, due to the weather condition varying from dry to rain and to snow, while the buffer index increased from 29% to 45% and to 94%.
基金Project(2012CB725402)supported by the State Key Development Program for Basic Research of ChinaProject(2012MS21175)supported by the National Science Foundation for Post-doctoral Scientists of ChinaProject(Bsh1202056)supported by the Excellent Postdoctoral Science Foundation of Zhejiang Province,China
文摘Traffic jam in large signalized road network presents a complex nature.In order to reveal the jam characteristics,two indexes,SVS(speed of virtual signal) and VOS(velocity of spillover),were proposed respectively.SVS described the propagation of queue within a link while VOS reflected the spillover velocity of vehicle queue.Based on the two indexes,network jam simulation was carried out on a regular signalized road network.The simulation results show that:1) The propagation of traffic congestion on a signalized road network can be classified into two stages:virtual split driven stage and flow rate driven stage.The former stage is characterized by decreasing virtual split while the latter only depends on flow rate; 2) The jam propagation rate and direction are dependent on traffic demand distribution and other network parameters.The direction with higher demand gets more chance to be jammed.Our findings can serve as the basis of the prevention of the formation and propagation of network traffic jam.