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25 December 2020, Volume 20 Issue 6 Previous Issue    Next Issue

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Impacts of Science and Technology on Transportation WANG Qing-yun, MAO Bao-hua 2020, 20(6): 1-8.  Abstract ( )   PDF (1725KB) ( )   Human is the creators of science and technology and also deeply affected by them. This paper analyzes the relationship between humans and the development of science and technology from the perspective of transportation. It interprets the actions of science and technology on transportation modes and structure. The study finds that science and technology have played growing impacts with a more obvious and stronger degree on the efficiency and service level. The evolution of science and technology themselves is faster and faster like snowballs. The situation makes it necessary for the transportation industry to pay more attention to long-term strategy and planning so as to avoid possible waste by overlapping investment under short-term tactics. The future applications of technologies as big data, internet of things, and the concept of sharing will not only cause the changes of efficiency, and benefit for human society, but also great transforms inconsistent with traditional views and even social ethics as well, which are worth studying from the perspective of social governance. During the 14th five years and even to 2035, it concludes several countermeasures. First, the top-level design should be done well at the government level based on the comprehensive understanding of future changes. Secondly, it is necessary to start the researches on the regulation for the coming transport products and services promoted by science and technology, which may conflict with current social cognition. Thirdly, strengthening the efficiency of existing transportation infrastructure is important both for operators and customers with the promotion of science and technology development. It finally suggests to study the extension services with improved performance for some transport infrastructures under the possible recession in future demand. An updated concept of supply and demand in the transportation industry seems coming soon toward our society, which means new challenges for transport professionals and decision-makers. References | Related Articles | Metrics

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Transportation Network Systems Engineering GUAN Wei, WU Jian-jun, GAO Zi-you 2020, 20(6): 9-21.  Abstract ( )   PDF (1484KB) ( )   Networking is the natural attribute of transportation systems. There are always inherent requirements of systems networking for construction and management of transportation infrastructure, the operation and service, as well as the administrative agencies and policies of transportation systems. In this paper, the concept of transportation network systems engineering (TNSE) is defined firstly, the state of the art of TNSE both in scientific research and practice are introduced from aspects of complex network analysis, networking operation management, and networking control & guidance. The existing scientific problems of TNSE are also summarized. The key scientific problem of complex network analysis for transportation systems is to explore the dynamic coupling and matching relationship between different transportation network topologies and the spatial-temporal evolution pattern of traffic dynamics, network capacity and reliability. The key scientific problem of networking operation management is how to realize the trade- off or Pareto optimality among multi- agents with benefits heterogeneity (governments, operating agencies, passengers) under the complex network structured transportation infrastructure. For the future development of transportation network systems engineering, we think that it is necessary to strengthen the research on the theory and methodology of integrated transportation network systems engineering, which should focus on scientific problems such as structural evolution mechanism of integrated transportation network, supply and demand balance mechanism of urban transportation network, complex structural characteristics and dynamic process of multi-layer integrated transportation network, as well as diversity and predictability of travel behavior, etc. Furthermore, the covering scopes of transportation network systems engineering also need to be fundamentally upgraded due to the dramatic change of transportation system accompanying with increasing of new emerging technologies. The flexible transportation network with nodes of self- driving, self- organizing, and self- decision- making ability and its shared operation mechanism will be an important research field of transportation network systems engineering in the future. References | Related Articles | Metrics

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Path Planning for Logistics Unmanned Aerial Vehicle in Urban Area ZHANG Hong-hai, LI Han, LIU Hao, XU Wei-wei, ZOU Yi-yuan 2020, 20(6): 22-29.  Abstract ( )   PDF (2195KB) ( )   This paper solves the path planning problem of logistics unmanned aerial vehicle (UAV) in the urban area. The grid method is first used to model the environment with the performance of UAV, task nature, and urban environment. A multi-constrained logistics UAV path planning model is then constructed to minimize the range, height change, and risk. And an improved A* algorithm is designed to solve the model. The heuristic function uses the linear combination of Euclidean distance and Manhattan distance to estimate the distance reasonably. A twoway search strategy is introduced to improve the search efficiency. The B-spline method is applied to optimize the path in order to ensure a smooth flight. The research results show that the proposed model is effective to achieve multi-objective performance. Compared with the traditional A* algorithm, the improved algorithm can solve for a shorter path with less altitude change and stable flight safety in less computational time. When the weight coefficients of the three sub-targets are 0.4, 0.1, and 0.5 respectively, and the weights of the two distances are 0.15 and 0.85 respectively, the UAV path planned by this algorithm is the best. References | Related Articles | Metrics

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Impact of Staggered Shifts on Disease Spread ——The Example of Shanghai ZHU Wei, WANG Jia-xin, CHEN Xin, ZHANG Yan, ZHANG Nan 2020, 20(6): 30-36.  Abstract ( )   PDF (1954KB) ( )   Staggered- shifts policy was proposed to suppress the disease spread. This paper aims to quantify its effectiveness. Based on the current commuting conditions reflected by the mobile phone grid data in Shanghai, this paper uses a multi-agent simulation model to analyze the spread of disease and to compare the effects of different staggered-shifts strategies. It is found that the staggered shifts increase people's mobility, and accelerate the spread of disease. The disease spreads faster as the rates of the staggered shifts increase. Individuals who go to work earlier have slightly less possibilities to be infected than those who go to work later. Individuals who have longer commuting distances, and live and work closer to the city center, are more susceptible and infectious. References | Related Articles | Metrics

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Impact Analysis of Transport Speed Technology on Passenger Transport HUANG Jun-sheng, ZHOU Qi, XIAO Zhong-sheng, DU Peng, FENG Jia, CHEN Hai-bo 2020, 20(6): 37-46.  Abstract ( )   PDF (2252KB) ( )   Under the background of technology promotion to achieve speed improvement, the impact of speed on passenger transport is analyzed in this paper. Firstly, the speed improvement of railway transport, air transport and road transport in history and the associated technology promotion are reviewed systematically. Secondly, with the rich connotation of speed, the basic characteristics of the passenger transport market are investigated from the perspective of speed reliability and rapidity. Then, with the speed improvement in the future, the position of different transport modes is explicitly analyzed, and the utility function of different travel modes and passenger's generalized travel cost is put forward based on different transport markets, and the evolutionary game theory and the Logit model are utilized to analyze the impact of speed improvement on transport structure of different passenger transport market. Several points have been concluded as below. Firstly, the most important factor related to traveler's choice is the door to door time which comprises the in-vehicle time and the time spent at the origin, transfer and destination points. Secondly, the structure of the transport market can be changed by speed promotion of different travel modes, transfer efficiency, and time reduction at origin, transfer and destination points. For short-distance trips, shortening time at origin transfer and destination points would significantly influence transport structure; whereas for long-distance trips, speed promotion may have a greater impact on transport structure. The market boundary is less than 800 kilometers between the high-speed railway with a maximum speed of 250 km/h and the civil aviation, but the boundary may be changed to about 1 200 kilometers for the high-speed railway with a maximum speed of 350 km/h. Thirdly, the reliability of speed has a significant impact on commuting passenger flow in urban areas. Fourthly, though science and technology are an important support to speed promotion, it is worthwhile to pay more attention to the economy and market purchasing power behind the realization of speed technologies. Finally, the research on the pricing of differentiated products related to speed is the key to promote transport operators to provide more efficient travel products. References | Related Articles | Metrics

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Impact of Manufacturing Offshoring and Reshoring on Development of Chinese Ports SHAO Li-hua, LI Ning-hai, TANG Qing, SONG Li-ying, WANG Xin-chang 2020, 20(6): 47-56.  Abstract ( )   PDF (2257KB) ( )   Over the past centuries, there have been great changes in the manufacturing industry around the world. With the progress of science and technology, the change of manufacturing cost, technology center and manufacturing center continually transferred and separated. In the 21st century, the rapid development of Chinese manufacturing industry has driven the growth of the volume of coastal ports. In recent years, influenced by the global manufacturing change, new trends of Chinese manufacturing industry commenced. On the one hand, manufacturing companies of developed countries restore to their native land. On the other hand, some laborintensive manufacturing companies offshore to southeast Asia whose cost of labor is lower compared with China. Consequently, the volume of manufacturing production will undoubtedly change to some extent, which will further affect the import and export volume and port throughput. This paper first analyzed the global manufacturing center's previous transfer situation and the characteristics of international cargo transport in different transfer stages. Secondly, the correlation between the throughput and the Chinese manufacturing industry is analyzed. Finally, the paper focused on the characteristics of the trend of offshoring manufacturing in China and the reshoring in the United States, and analyzed their influence on the development of Chinese ports. The results show that the throughput of Chinese ports is significantly correlated with the value- added of secondary industry, the bilateral trade volume between China and the United States and the total amount of China exports and other factors. Simultaneously, driven by the reduction of Chinese labor cost advantage and the reshoring policy of the U.S. manufacturing industry, the trend of offshoring of China's manufacturing industry will strengthen, and the reshoring trend of the U.S. manufacturing industry may be maintained. Considering the influence of offshoring and reshoring of manufacturing industry, the growth of Chinese port throughput will be weak, and the structure of the freight category will shift from dry bulk transportation to container transportation. In the future, Chinese ports should adjust the allocation of capacity and resources of collection and distribution. Consequently, priorities should be put on container transportation. References | Related Articles | Metrics

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Behavior of Long-distance Travel Mode Choice under the Duration of Public Health Emergencies LUO Chen, DONG Qing, YAO Qing, ZHANG Hai-rong, WANG Qian-ru 2020, 20(6): 57-62.  Abstract ( )   PDF (1274KB) ( )   In order to analyze the effects of risk perception attribute on the long- distance travel mode choice behavior under the duration of public health emergencies, a multivariate Logit model is built for travel mode choice considering residents' risk perception difference. According to the 1 643 effective questionnaires collected from the internet during the COVID-19 in March 2020, the model parameters are calibrated using SPSS. The main risk perception factors affecting travelers' travel mode choices were obtained, and the sensitivity analysis of each factor was carried out. The results show that the prevention and control measures and the understanding of the measures have a significant influence on the choice of travel mode. Compared with air transportation, the increased exposure rate has a negative influence on the choice probability of railway transportation and a positive influence on the choice probability of road transportation. Keeping low air prices during the COVID- 19 and increasing publicity of prevention and control measures for air transport can improve the choice probability of air transportation. References | Related Articles | Metrics

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Assessment of Infection Risk Based on Travel Behavior Analysis ——Example of Jiangsu Province Travel during COVID-19 2020, 20(6): 63-70.  Abstract ( )   PDF (2325KB) ( )   In order to correctly evaluate the travel infection risks during the COVID- 19 pandemic, this study proposed an infection risk assessment model based on the travel behavior analysis. Using the epidemiological survey data and online questionnaire data in Jiangsu, China this study developed and calibrated the travel behavior models for virus carriers and ordinary individuals. The travel behaviors of virus carriers and ordinary individuals were also compared. The infection risks were evaluated for different travel modes and travel activities. The results indicate that: (1) implementing strict traffic control measures significantly reduces the infection risk; (2) the infection risk of medical treatment travel activities is significantly higher than other travel activities; (3) business or leisure travel activities expose to a higher infection risk in the early stages of the pandemic; (4) the risk of nonmotor vehicle travel is relatively low. References | Related Articles | Metrics

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Impact of COVID-19 on the Elderly's Bus Travel Behavior LIU Jian-rong, HAO Xiao-ni, SHI Wen-han 2020, 20(6): 71-76.  Abstract ( )   PDF (1278KB) ( )   COVID-19 has caused huge negative impacts on traffic and transportation. Existing research focused on the impact of COVID- 19 on the traffic during the outbreak phase. There are still few studies related to the impact of COVID- 19 on travel behavior during the post- epidemic phase. This paper analyzed the impact of COVID-19 during the post-epidemic phase, travelers' demographic characteristics, and perception of the COVID- 19 severity on the elderly's travel behavior, with the confirmative factor analysis and Logit modeling. The results show that COVID-19 and perception of its severity have no significant impact on the elderly's short-distance trips. However, they have a significant impact on the elderly's willingness to travel by bus. Furthermore, these two factors have significant impacts on the elderly's trip frequency and bus trips. References | Related Articles | Metrics

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Influence of the Elderly on Family Travel Behavior with Time Sociology HE Bao-hong, LI Jing, WANG Yu-jia 2020, 20(6): 77-83.  Abstract ( )   PDF (1657KB) ( )   This paper illustrates the influence of behavioral interactions between the elderly and co-residents on individual travel decisions in the family's micro-social context. From the perspective of time sociology, we take the family with the elderly in Kunming as a unit, and uses the family contributions index to quantify the degree of the elderly' housework activities. A structural equation model is constructed to reveal the influence of the elderly on the time structure of family members' daily activities, and further analyze the interaction mechanism of activities between members. The result shows that when the contribution of the elderly increases, the interactive utility of the family members in non-commuting activities weakens. In addition, female parents' activity-travel mode is significantly affected by the contribution of elderly families more than male parents, because female parents present an invisible“time poverty”feature in the time structure. Besides, the female parents influenced by the elderly give priority to the timing of housework activities when making decisions on non- commuting activities, while male parents give priority to freedom event arrangement. References | Related Articles | Metrics

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Intervention Effect Analysis on Traffic Safety in Urban Core Areas under Influence of COVID-19 ZHAO Dan, WANG Jing-sheng, ZHOU Yan, LIU Dong, XING Li-li 2020, 20(6): 84-90.  Abstract ( )   PDF (1560KB) ( )   The traffic safety characteristics were changed in urban core areas under the influence of COVID-19. In this paper, a one- dimensional time series was constructed based on the data of traffic accident reception and handling. Through the descriptive analysis, the time distribution characteristics of traffic accident under COVID-19 epidemic was studied. In view of the non- stationary characteristics of traffic accident sequence, wavelet decomposition technology was used to extract the structural mutation point of the sequence under the COVID-19 controlling policies, which excluded the influence of the Spring Festival holiday. With the supported vector machine(SVM) method, an intervention model was established to evaluate the impact of COVID-19 epidemic prevention policies on traffic accidents. The research results show that the rigor traffic prevention policies have reduced the daily traffic accident rate by 12.23 on average, and then it attenuates at a rate of 68.7%, and then to recover at a rate of 30.9%, which lasts until the implementation of the policy of resuming work and production; and the relatively lenient traffic control policies stabilizes the reduction of daily accident rate at 11.707 on average. References | Related Articles | Metrics

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Perimeter Control Strategy of Urban Road Network Considering Superblocks ZHANG Ling-xuan, SHUAI Bin, DING Dong, ZHANG Shi-hang, WANG Rui 2020, 20(6): 91-98.  Abstract ( )   PDF (1793KB) ( )   In order to relieve the traffic congestion of the central area in an urban road network, a multi- region perimeter control strategy based on networks with a closed superblock was proposed. The urban road network was first divided into three subregions: a central area, a suburb area, and a closed superblock. The dynamic equilibrium equations of traffic flows among three subregions were established based on the Macroscopic Fundamental Diagram (MFD). A multi-region perimeter control model was constructed by considering the route choice behavior of vehicles, in which the objective function was to maximize the trip completion rate of the central area, and the control variables were the toll charged and the number of gates at the perimeters. A numerical case according to the real data was used to verify the validity of the proposed model. The results indicate that the service capacity of the central area under the proposed perimeter control method is 7% higher than that without the perimeter control. The proposed perimeter control model can effectively improve the uniformity of traffic density distribution among regions to enhance the network service capacity. It is an effective and practical way to carry out the perimeter control by changing the number of gates of superblocks. References | Related Articles | Metrics

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Trip Purpose Inference of Group Passengers Based on Ticket Sales Data QIAN Jian-pei, SHAO Chun-fu, LI Jun, CAI Nan, HUANG Shi-chen 2020, 20(6): 99-105.  Abstract ( )   PDF (1929KB) ( )   To obtain trip purpose missing in big data derived from intercity transportation for deeper application, by drawing an analogy between the decision- making of trip purpose in group passengers and the generation of topics in texts, this study develops an approach for trip purpose inference under the unsupervised learning framework. First, a modified topic model embedded with the generation process of start time was proposed. Second, methods for reconstructing group passengers and designing semantic features were presented. Finally, the parameters were estimated using Gibbs sampling. Model comparison based on the survey data manifests that the performance of identifying personal affairs is raised by 7.7 percent using the proposed model; a case study based on the ticket sales data demonstrates that the precision of predicting start time is 90%, providing an indirect proof of its reliability. The topic annotation reveals that not only trip purpose corresponding to four typical patterns are inferred, but also anomalies beyond existing knowledge are recognized. In regard to the road passenger transport, trip purpose configuration shows a regional disparity, and whether high speed rail (HSR) has reached has diverse negative effects on the ridership of different trip purposes. References | Related Articles | Metrics

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Experiment and Model of Day-to-day Route-choice Behavior under Different Information LIU Shi-xu, WANG Zhi-yu, GUAN Hong-zhi, YAN Hao, HE Zhao-yang 2020, 20(6): 106-113.  Abstract ( )   PDF (1555KB) ( )   To investigate the influence of Advanced Traveler Information Systems (ATIS) on travelers' day-today route-choice behavior, this paper designed five groups of behavioral experiments with different ATIS market penetration (0, 25%, 50%, 75%, and 100%) based on the Braess network. The results show that the flows of the three routes and the choice frequency of the new route kept continuous fluctuations throughout the whole experiments. With the increase of the ATIS market penetration, the average travel time tends to the user equilibrium, and the choice frequency of the new route shows an increasing trend. We also found that with the increase of ATIS market penetration, the subjects' preference for the new route increases and the effect of the Braess paradox is more obvious. Based on the five groups of experimental data, a common Logit model and a random utility Logit model based on panel data were respectively proposed to describe the route-choice behavior of the subjects. The results show that when ATIS market penetration is 0, the common Logit model is better. When the ATIS market penetration increases or even reaches 100%, the random utility Logit model becomes better. The individual differences of travelers without ATIS are smaller than those with ATIS. References | Related Articles | Metrics

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Stability Analysis of Complex Heterogeneous Traffic Flow under Connected and Autonomous Environment LI Xia, WANG Yi-ge, CUI Hong-jun, ZHU Min-qing, WANG Xin-tong 2020, 20(6): 114-120.  Abstract ( )   PDF (2090KB) ( )   Considering the vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication technologies of connected vehicles, the stability of the complex heterogeneous traffic flow composed of connected vehicles and regular vehicles was studied. Based on the Lyapunov theory, the stability of heterogeneous traffic flow under different communication technologies was compared. Then the stability conditions and stability region of heterogeneous traffic flow were analyzed when V2V- based connected vehicles, V2V/V2I- based connected vehicles, and regular vehicles are mixed with different proportion rates. The numerical simulations were carried out to verify the correctness of the theoretical analysis. The results show that the heterogeneous traffic flow mixed with V2V/V2I- based connected vehicles has a better stability effect than V2V- based vehicles. In the case of the V2V- based and V2V/V2I- based connected vehicles merge into traffic flow composed of regular vehicles, low penetration rates of V2V- based connected vehicles do not result in significant stability improvements, whereas stability is improved even at low penetration rates of V2V/V2I- based connected vehicles. In addition, when the penetration rates of V2V- based connected vehicles are low, the critical velocity of equilibrium increases approximately linearly as the proportion rates of V2V/V2I-based connected vehicles increases. References | Related Articles | Metrics

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An Optimization Model for Dynamic Lane Grouping and Signal Phase at Intersection SONG Xian-min, ZHANG Ya-nan, MA Lin 2020, 20(6): 121-128.  Abstract ( )   PDF (1909KB) ( )   In previous studies, dynamic lane grouping (DLG) is optimized under the fixed or pre-set signal timing schemes, which results in the waste of time- space resources of the intersection. This paper proposes a two- part model to collaboratively optimize the dynamic lane grouping and signal timing parameters according to the realtime traffic demand, with the signal cycle, green time, and optimized lane number as constraints, and with the goal of minimizing the average delay of vehicles at the intersection. The first part is to generate all the feasible DLG alternatives based on lane balance, which are taken the input parameters of the second part of the model. The second part is to optimize the dynamic lane scheme and the signal scheme. The proposed model is compared with the conventional signal timing method in simulation. Results indicate that the proposed model reduces more intersection delay than conventional methods, and it can effectively improve the utilization rate of spatial and temporal resources at signalized intersections. References | Related Articles | Metrics

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Identification and Retrieval of Critical Segments Based on Travel Time Effect LI Jun-xian, WU Zhi-zhou, SHEN Zhou-biao 2020, 20(6): 129-135.  Abstract ( )   PDF (2040KB) ( )   Considering the actual functions of road segments in the network, a method for identifying critical segments is proposed based on the correlation between the segment and the route travel- time series. Drawing lessons from the Monte Carlo method, 100 thousand random routes created with ground truth data verify this method's feasibility. Several segments that have a crucial impact on the travel time of Shanghai's road network are identified to form a set. Taking the set as a reference, a Binomial Logit Model is built to retrieve critical segments actively, with some new attributes of the segment's travel time series extracted by the Fuzzy Clustering Method and Iterative Cumulative Sums of Squares Algorithm, and some primary attributes as well. The comparison of the model with the basic model and the random classifier shows that the maximum normalized travel time curve's clustering results can improve the critical link identification model's effectiveness. As to structural change points of the travel time logarithmic difference sequence, they show apparent time aggregation characteristics at the road network and road section levels. Although the number of structural change points has no significant correlation with the link's criticality, it has little correlation with the typical volatility index. It can be retained as an index to describe the frequent and aggregation of travel time fluctuations. References | Related Articles | Metrics

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Stochastic Newell Car-following Model Based on Propagation of Disturbances ZHANG Jian-bo, ZHU Yuan-qi, SUN Jian-ping 2020, 20(6): 136-144.  Abstract ( )   PDF (2147KB) ( )   In order to study the car following behavior on expressways, high-time resolution trajectory data of motor- vehicles were extracted from the traffic video of the expressway in Beijing. First, it is found that under different speed intervals, the headway of the following vehicle obeys the lognormal distribution. Second, the Dynamic Time Warping algorithm was used to extract parameters including reaction time and disturbance propagation speed, and the probability distribution functions were respectively calibrated. It is proved that the peak of the reaction time distribution falls into the interval of 1.0 s and the mathematical expectation of the reaction time is 1.57 s. Further, a novel stochastic Newell car- following model based on the disturbance propagation characteristics was proposed considering the relationship among reaction time, disturbance propagation speed, and time headway. The parameters of disturbance propagation speed under different speed intervals were demarcated. Finally, the simulation analysis shows that the new stochastic Newell model can better characterize the stochastic characteristics of car-following behavior and disturbance propagation, and generate the expected traffic flow fundamental diagram. References | Related Articles | Metrics

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Car-following Behavior and Model of Chinese Drivers under Snow and Ice Conditions YANG Long-hai, ZHANG Chun, QIU Xiao-yun, WU Ying-tao, LI Shuai, WANG Hui 2020, 20(6): 145-155.  Abstract ( )   PDF (2457KB) ( )   This paper analyzes the driver's driving behavior characteristics under snow and ice conditions and establishes a car- following model to consider the driver's behavior characteristics. By conducting a real-car following experiment, the driving behaviors of the drivers are compared under normal conditions and snow and ice conditions. Based on the theory of task difficulty balance, a task difficulty module containing human factors parameters is constructed, and it is introduced into the improved Intelligent Driver Model. The vehicle trajectory data is used to calibrate and verify the validity of the model. Research shows that, when affected by external stimuli and his own driving ability, the driver will dynamically adjust the driving state in real time during the carfollowing process, to keep the expected distance and the speed consistent with the vehicle ahead. Under snow and ice conditions, drivers' choices of time headway and variation of time headway fluctuation amplitude are different, and human factor parameters introduced by the model can better capture such difference. The validation of the model indicated that the performance of the new model was better than the traditional IDM model in 6 simulation scenes, and it has better robustness. The research results can provide theoretical support for the formulation of traffic management measures under snow and ice conditions. References | Related Articles | Metrics

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A Hierarchical Delay Layout Model for Electric Vehicle Charging Stations Considering Cruising Capability CHEN Wei-wei, XU Mao-zeng, XING Qing-song 2020, 20(6): 156-162.  Abstract ( )   PDF (1710KB) ( )   A hierarchical delay layout strategy exhibits great potential for reducing the investment costs of electric charging stations. This paper first analyzes the specific characteristics of the hierarchical delay layout strategy, i.e., the space dimension with the endurance capacity radius to realize the neighborhood connection coverage, the time dimension with the double- helical synchronous growth of the traffic flow, and the financial dimension with the efficient allocation of public resources. A hierarchical delay layout optimization model is formulated with an extended OD traffic network based on the closure site selection method. The model is solved by a newly designed stepwise- boosting algorithm. Real cases are adopted to verify the proposed model and algorithm. And the investment effects are analyzed. Experimental results reveal that the hierarchical delay layout strategy can save the public investments. In specific, the higher the investment is, the larger saving effects would be obtained. The longer the vehicle travel range is, the smaller number of the charging stations would be deployed, which contributes to the investment saving for charging stations. In general, this research would provide certain enlightenments in the practical hierarchical delay layout movement for regional charging station investment decisions. References | Related Articles | Metrics

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A Bi-objective Integrated Optimization Model of High-speed Train Rescheduling and Train Control LONG Si-hui, MENG Ling-yun, WANG Yi-hui, LUAN Xiao-jie, ZHANG Peng 2020, 20(6): 163-169.  Abstract ( )   PDF (1760KB) ( )   Real- time train rescheduling and train control are of crucial importance for punctual and energyefficient high-speed train operations. This paper proposes an integrated optimization model for the high-speed train rescheduling and train control. The objectives of the model are to minimize the total train delay time and total energy consumption. The model optimizes the train trajectories and rescheduled timetable at once. Based on the detailed train traction calculation, the model integrated the solution space of train rescheduling and train control by blocking time theory, whereas the two problems in the previous research are optimized separately. The model could obtain the detailed running time of a train on each block section and the headway time between two adjacent trains according to the train speed, braking performance, clearing time and release time of the signaling system, and the length of the block section. A piecewise approximation method is designed to reformulate the non-linear constraints, which transforms the complicated non-linear model to a mixed-integer linear programming (MILP) model. In numerical experiments, a set of Pareto solutions is obtained for the bi-objective optimization problem. According to the experimental results, compared with the single- objective optimization model, the proposed biobjective integrated optimization method could reduce the energy consumption and train delay time by up to 2.46% and 7.33%, respectively. References | Related Articles | Metrics

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Optimization of Train Headway and Traction Energy Consumption in Urban Rail Transit GAO Hao, GUO Jin, ZHANG Ya-dong 2020, 20(6): 170-177.  Abstract ( )   PDF (2061KB) ( )   Focusing on the characteristics of dense train tracking operation during the peak hour in urban rail transit, this paper takes both reducing traction energy consumption and improving line capacity as objectives in the train driving strategy optimization. The calculation method of traction energy consumption and minimum headway is given under the moving block system. Considering the constraint of safe running and punctual arriving, the twoobjective optimization model is constructed. A dynamic programming based approach combined with ε -constraint method is proposed to solve the model. A case study of Yizhuang urban rail line was executed and a set of Pareto solutions were achieved which reflecting the trade-off between those two objectives. The results showed that the multi-step braking strategy during the phase of entering a station can compress the minimum headway effectively. To reduce the increased running time because of the multi- step braking strategy, trains need to improve their velocity before the phase of entering a station to satisfy the constraint of punctual arriving, which consumes more traction energy. References | Related Articles | Metrics

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Day-to-day Similarity of Individual Activity Chain of Public Transport Passengers LIN Peng-fei, WENG Jian-cheng, HU Song, JING Yun-qi, YIN Bao-cai 2020, 20(6): 178-183.  Abstract ( )   PDF (1307KB) ( )   Smart card data provides the data basis for the study of long-term travel regularity of public transport passengers. Based on the smart card data from April to May 2018 in Beijing, this study constructed the passenger activity chain in three steps, including extracting the passenger activity location, inferring the residence location, and identifying the activity type. The PrefixSpan algorithm was used to extract the frequent sequence patterns of activity chains for regular, senior and student card users. Levenshtein distance was applied to measure the day-today similarity of the three types of passengers' daily activity chain. The results show that about 70% of users in each type have a symmetrical pattern of frequent activity sequences. The similarity of regular card and student card users is higher than senior card users, with an average of 0.645, 0.649, and 0.530, respectively. For all the three types of users, the differences in day-to-day activity chain sequences between workdays and weekends are larger, but the similarities within workdays or within weekends are higher. This study helps to quantitatively analyze the regularity of passenger travel and activity and provides evidence for scientific optimization of public transport services. References | Related Articles | Metrics

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Modeling and Simulation Verification of Guiding Path Planning Model ZHAO Qi, ZENG Ye, ZHANG Li-li, WANG Li 2020, 20(6): 184-190.  Abstract ( )   PDF (1568KB) ( )   The information overload problem may occur when there are several traffic guidance signs, which affect vehicle driving. This paper proposes a guiding path planning model based on an A* algorithm to solve the problem. Because the information overload at specific nodes affects the actual cost of the guiding path, a penalty coefficient is adopted in the proposed model to avoid the guiding path selection which may an induce information overload phenomenon. A case study is conducted based on VISSIM according to the data extracted by using secondary development function in VISSIM. The proposed model is used to search a guiding path for an OD pair in the road network. By comparing with the model without the penalty coefficient, the results of the guiding path selections and traffic guidance sign layouts prove that the proposed model can effectively avoid the information overload problem. References | Related Articles | Metrics

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Improvement of Classic Random Regret Minimization Model Considering Heterogeneity YANG Fei, HOU Zong-ting, ZHOU Tao 2020, 20(6): 191-196.  Abstract ( )   PDF (1239KB) ( )   Due to the lack of consideration of heterogeneity in the traditional choice model based on regret theory, there may be errors in the interpretation of the real choice behavior. This paper uses the Weber ratio to consider the heterogeneity of travelers' perception for attribute variable to improve the classic random regret minimization model, and takes taxi- hailing choice behavior as an empirical study. Three choice models are established based on the random utility maximization, classic random regret minimization, and improved classic random regret minimization, respectively. The results suggest that the calibration results of the three models are consistent, and the improved model's goodness of fit (0.271) and hit ratio (75.8%) are both better compared with the other two models. Besides, the improved model can better describe the semi- compensation principle and compromise effect in the multidimensional attribute decision- making process. And the improved model has a strong explanatory capability to the real choice behavior. References | Related Articles | Metrics

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Severity Factors Analysis Model of Traffic Accident on Combined Horizontal and Vertical Alignments JI Xiao-feng, WU Ya-xin, HAO Jing-jing, FANG Rui, HU Cheng-yu 2020, 20(6): 197-204.  Abstract ( )   PDF (1431KB) ( )   To analyze the severity factors and influence mechanism of traffic accidents on combined horizontal and vertical alignments, the potential variables influencing accident severity were selected first. And an ordered Logit model was used to obtain significant independent variables influencing accident severity. A partial proportional odds model was used to modify the parameters of variables. The two- stage model (TSM) was then proposed for severity factors analysis of accidents on combined horizontal and vertical alignments. A verification analysis was conducted by taking Yuanmou- Shuangbai secondary road in Yunnan province as a case area. The results show that the TSM has a higher fitting degree than ordered probability models and is more suitable for the study. In particular, seven factors including the number of vehicles, curvature of horizontal curves, curvature of vertical curves have positive influences on general and above accidents, while the other three factors including driver's gender and access segment have negative influences. In terms of influence degree, the impact of the access segment is the largest (marginal effect: 14.466% ), followed by the drivers' gender (10.581% ), and the length of vertical curves is the smallest. References | Related Articles | Metrics

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Conflict Resolution Model Based on Multi-vehicle Cooperative Optimization at Intersections 2020, 20(6): 205-211.  Abstract ( )   PDF (1930KB) ( )   The traditional autonomous driving vehicles designed the conflict resolution algorithm based on the assumption of the right of way. However, the right of way was not clear in most cases of the mixed traffic of manual and autonomous driving, which will bring great trouble to the decision-making of autonomous vehicles. This paper proposed a conflict resolution optimization method for autonomous vehicles at intersections. The multiobjective optimal control theory was used to plan the speed for the conflicting vehicles, so as to achieve the purpose of cooperative driving. Finally, the simulation experiments of cooperative and non- cooperative conflict resolution were carried out. The results show that the conflict resolution of multi-vehicle cooperative driving can optimize the speed trajectory of vehicles to improve the overall driving efficiency, and the performance of various stakeholders is balanced relatively. Compared with non-cooperative conflict resolution, the time of conflict resolution is shortened, and the average delay per vehicle is reduced by 1~2 s at the intersection, and the average reduction is approximately 5%. The research results can provide a reference for an autonomous cooperative driving when the conflict occurred. References | Related Articles | Metrics

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Equilibrium Model of Airport Group System under Uncertain Conditions SHENG Yin, CHEN Xin, MAO Yi 2020, 20(6): 212-218.  Abstract ( )   PDF (1686KB) ( )   To discovery the mechanism of the passenger distribution in an airport group system, this paper proposes a passenger equilibrium model. This model jointly considers ground and air traffic from the perspective of an entire trip. A travel cost model of passengers is designed based on travel time, ticket price, time cost in an airport, and the type of passengers. Because of the uncertain of route time, mean- excess travel time is used to describes the mean and variation of route time. Based on the travel cost model, the equilibrium model based on Logit model is represented by a variational inequality. Then the variational inequality is solved by the projection and contraction method, and the equilibrium state among airports is acquired. Numerical experiments are conducted, and the results show that the model can effectively represent the distribution of passengers. Modifying route time, service standards of airports, and ticket prices are all helpful to balance the passengers in the airport group system. References | Related Articles | Metrics

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Analysis Model of Travel Behavior in Public Transportation Considering Residential Location ZHONG Yi-ying, CHEN Jian, SHAO Yi-ming, LI Rui 2020, 20(6): 219-225.  Abstract ( )   PDF (1346KB) ( )   In order to explore the impact of residential location on travel behaviors in public transportation at different levels, a multilevel structural equation model was constructed that includes residential location and psychological factors, based on the theory of planned behavior and group dynamics theory. The model also considered the influence of individual and community factors on travel choice. The model parameters were calibrated by Mplus. The results show that the influence significance of different variables is different on travel behavior intention. The influence significance of individual factors on behavioral intention is residential location (0.665), subjective norm (0.664), behavioral attitude (0.577), and perceived behavioral control (0.547); whereas the influence significance of community factors on behavioral intention is behavioral attitude (0.736) and residential location (0.646). References | Related Articles | Metrics

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Improved Model and Algorithm for Optimizing Collaborative Trajectory Options Program GUO Ye-chen-feng, HU Ming-hua, ZHANG Ying, XIE Hua 2020, 20(6): 226-232.  Abstract ( )   PDF (1832KB) ( )   To optimize the collaborative trajectory options program (CTOP), the Gini coefficient is firstly introduced to define a new metric of equity. A bi- objective integer nonlinear programming model is formulated considering the performance of efficiency and equity. An improved genetic algorithm is applied to solve the model, which uses an array of integers representing a flight priority order to code the chromosome and adds a process to choose the satisfactory solution. According to the simulation, the final satisfactory solution based on the improved algorithm brings a 9.3% increase in the airspace operating efficiency and a 33.7% increase in the airlines' equity, compared with the solution solved by the current practical algorithm. The result shows the improved algorithm produces the true Pareto frontiers quickly, and the final satisfactory solution both improves the efficiency and equity significantly. References | Related Articles | Metrics

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An Integrated Scheduling Model of Refueling Schemes and Speed Optimization of Consecutive Voyages for Tramp Ships WANG Chun-juan, CHEN Chao 2020, 20(6): 233-239.  Abstract ( )   PDF (1499KB) ( )   Currently, expensive marine fuel prices and the price difference at different ports have significant effects on the refueling port selection, the refueling volume, and the speed optimization on their routes. The different fuel prices affect the trade-offs between refueling levels and cargo volume. The different shipping speeds affect the balancing effects of the time consumption costs and fuel consumption costs. The scheduling decisions also affect the subsequent voyages. Considering the complex relationships and trade-offs mentioned in the factors above, an integrated scheduling solution of refueling schemes and speed optimization of consecutive voyages for tramp ships was proposed in this paper. With the objective of maximizing the profits of consecutive multiple voyages, a multiple nested expected value processing technique with a mixed integer nonlinear programming method is designed to build the model. Finally, with practical case analysis, it is verified that the integrated scheduling model proposed in this paper has obvious practicality and benefits. References | Related Articles | Metrics

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Evaluation of Driving Comfort on Slopes of Secondary Highway in Mountainous Area Based on Driver Workload HU Li-wei, YIN Xiu-fen, ZHANG Su-hang, FAN Zi-jian, GUO Zhi 2020, 20(6): 240-246.  Abstract ( )   PDF (2096KB) ( )   In order to quantitatively evaluate the driving comfort on the mountain highway slopes, this paper collects the data of the driving load by the real driving experiments on the secondary highway in Wendu City of Yunnan Province. Firstly, the driving load model is established by analyzing the influence of gradient and length of slopes, and acceleration (deceleration) on the driving load. Secondly, the 50th and 85th percentile growth values of heart rate are used to divide driving load level, and the threshold analysis of driving comfort is carried out with the established model to determine the range of gradient and acceleration (deceleration) corresponding to different driving comfort. Finally, the rationality of the model and threshold division of driving comfort is verified. The results show that: gradient and acceleration (deceleration) are significant variables for driving load, and there is only a weak correlation between slope length and driving load. The established model in this paper is effective and the threshold division is reasonable, which can provide a reference for the study of driving load on the low-grade highway. References | Related Articles | Metrics

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Urban Activity Clustering Method Based on Dirichlet Process Mixture Model CHEN Zhong 2020, 20(6): 247-252.  Abstract ( )   PDF (2450KB) ( )   The mobile phone data not only provides the track record of individual travel, but also provides a basis for analyzing the spatial distribution characteristics of urban activities. This paper proposes a city activity feature clustering method based on the Dirichlet Process Mixture Model. Based on the residents' OD matrix extracted from mobile phone signaling, the number of arrivals and departures of each base station is used as a representation of the spatial location of the base station. The activity characteristics of the research feature clustering method. This method introduces Dirichlet distribution as the prior distribution, and estimates the number of feature clusters from the Chinese restaurant model. Compared with other clustering methods, the major advantage of this method is that there is no pre- specified number of clusters in the method, which avoids the defect of pre- specifying the cluster number in traditional clustering methods. This method is applied to the clustering of urban activity characteristics in Sanya, which can effectively reflect the activity characteristics of different urban functional groups. References | Related Articles | Metrics

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Evaluation of Eco-driving Behavior and Fuel-saving Potential of Large Freight Vehicles 2020, 20(6): 253-258.  Abstract ( )   PDF (1387KB) ( )   Improving driving behavior and promoting eco- driving are important approaches to reduce fuel consumption and pollution emissions of on- road vehicles in the future. We collect on- board diagnostic (OBD) system data with the position, speed, and fuel consumption per second from 199 heavy- duty freight vehicles in four days. We propose statistical measures to judge five inefficient driving behaviors, including rapid acceleration, over- rapid acceleration, rapid deceleration, over- rapid deceleration, and excess idle time. We further establish a panel data based fixed effects model to estimate the effects of inefficient driving behaviors on fuel efficiency as well as fuel-saving potentials of improving these behaviors. Our results show that excess idle time and over-rapid deceleration significantly increase fuel consumption, and the fuel-saving potentials are 2.6% and 3.8%, respectively. References | Related Articles | Metrics