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    25 February 2021, Volume 21 Issue 1 Previous Issue    Next Issue

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    Analysis of Transportation Mode Selection Based on Travel Surplus Theory
    WU Qun-qi, WANG Jia-bin, WANG Rui, SUN Qi-peng
    2021, 21(1): 2-7. 
    Abstract ( )   PDF (1256KB) ( )  

    This paper emphasizes the independent value and characteristics of travel, establishes the theory of travel surplus, and reveals the mechanism of travel demand subjects choosing the mode of transportation service by taking the maximization of travel surplus value as the criterion. The characteristics of travel value were summarized as cognition, difference and timeliness, and the travel demand was divided into three categories based on timeliness, and the corresponding travel value function was given. The characteristics of travel cost were summarized as timeliness, difference and uncertainty. The travel cost function of the whole travel process was constructed. By combining travel value's and travel cost's functions, a transportation mode selection model based on travel surplus value was constructed. The applicability of the model was verified by a simulation example. The results show that the model avoids the limitations of utility theory in terms of demand heterogeneity, travel value measure, and can provide new research direction for the study of passenger travel mode selection.

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    Multi-network Congestion Risk Propagation Model Considering Driver Behavior
    HUANG Jian-hua, SUN Meng-ge
    2021, 21(1): 8-15. 
    Abstract ( )   PDF (2127KB) ( )  

    The risk propagation process of urban road traffic congestion is affected by many factors, such as congestion warning information, traveler behavior characteristics and resident traffic flow distribution. In this paper, a multinetwork model is proposed including road network, information network and travel network. The propagation mechanism of urban road congestion risk under multi- network warning information is discussed using the improved UAU- SIR model. With the analysis of road network characteristics of typical cities in China, a network generation model is developed to reflect the real road conditions. The congestion risk propagation is analyzed through the influence of road network topology and travelers' behavior characteristics. The results of numerical simulation show that traffic warning information significantly affect the propagation of road congestion in case of serious congestions. The propagation threshold of congestion risk is related to the topology of road network, warning information, the behavior characteristics of travelers respond to warning information and the information transmission rate. Compared with the simulation road network, the ER random network has lower burst threshold and wider propagation area. It suggests that when making the information strategies, traveler's risk attitude and perception to congestions should be considered. Improving information communication intensity is helpful to maintain the stability of traffic flow.

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    Multimodal Timetable Optimization Between Urban Transport Hubs Considering Elastic Demand
    LU Tian-wei, YAO En-jian, YANG Yang, HUAN Ning, CHEN Lin
    2021, 21(1): 16-22. 
    Abstract ( )   PDF (2181KB) ( )  

    The existing operation of the integrated transport corridor between urban transport hubs appears to have poor coordination among travel modes and low transport efficiencies. In response to these problems, this paper proposes a multimodal timetable optimization method for urban passenger transport hubs and considers elastic transport demand. Based on the multinominal Logit model, the study developed a passenger travel mode choice behavior model to analyze the impact of timetable adjustment on the travel choices. In the multimodal timetable optimization model, the objective was the minimal total passenger waiting time, minimal total number of timetable adjustments, and minimal total timetable adjustment. The model constraints include elastic demand, time windows, and capacity limitations. A solution algorithm was designed using the non-dominated sequencing genetic algorithm and the passenger flow loading simulations. The“Beijing South Railway Station to Beijing Capital International Airport”multimodal corridor was used as a case study to verify the effectiveness of the model. The results show that the travel demand of each mode has some obvious elastic changes because of the proposed timetable optimization scheme. 10 timetable optimization schemes were obtained by solving the proposed model, and the overall optimization was more effective than the conventional model. The final selected scheme indicated the total passenger waiting time was reduced by 10.36%.

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    A Timetabling Model for High-speed Railway Based on Accessibility of Air and High-speed Rail Intermodality Service
    KE Yu, NIE Lei, YUAN Wu-yang
    2021, 21(1): 23-29. 
    Abstract ( )   PDF (1662KB) ( )  

    One of the advantages of the air and high- speed rail (AH) intermodality service is that it improves OD (Origin-Destination) accessibility and further provides more opportunities for the areas served by the airport. Two types of services, namely“high-speed railway to air”and“air to high-speed railway”are considered in the AH intermodality service. Two kinds of variables are introduced to express the connections between trains and flights as well as OD accessibility. And OD accessibility constraints for the AH intermodality service are proposed to depict the relationship between arrival times and departure times of trains, connection variables, and OD accessibility variables. Based on key ODs of AH intermodality service, given the flight timetable and original high-speed rail timetable, the paper proposes a bi-objective optimization model to maximize the number of ODs and minimize the shift of timetabling by adjusting the arrival time and departure time at each station. A case study of Shijiazhuang Zhengding Airport is then processed to verify the validity and feasibility of the model with the practical data of Beijing- Zhengzhou section in the BeijingGuangzhou high- speed rail corridor, and it is solved by ILOG CPLEX. The result shows the proposed model can improve OD accessibility of the AH intermodality service.

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    Freight Mode Choice Behavior Model Incorporating Spatial Characteristics
    LIU Hao, ZHANG Rong, ZHU Li-chao
    2021, 21(1): 30-35. 
    Abstract ( )   PDF (1216KB) ( )  

    One important reason for the low share of railway transportation in the freight market is that railway service providers fail to accurately grasp shippers' mode choice behavior and thus cannot provide competitive freight service. Based on the 116 shippers' behavior data from adaptive experiments, this paper constructs a multinomial Logit model and a mixed Logit model incorporating time, cost, cargo characteristics and choice inertia, which also introduces the interaction between spatial characteristics and time to reveal the effects of time on utility under different spatial characteristics. The results show that, in addition to transportation time and cost, the density of cargo, choice inertia and shippers' characteristics affect the freight mode choice behavior significantly. Because of the differences in distance, cargo type (value) and economic development level, the freight values of time with the same origin region but different destination regions are significantly different. The values were the highest in Eastern China and Southern China and the lowest in Central and Northern regions.

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    Predicting Optimal Route Based on Link-to-link Transition Probability
    LI Jun, GUO Yu-wei, YE Wei
    2021, 21(1): 36-40. 
    Abstract ( )   PDF (1613KB) ( )  

    A method to find optimal route based on link-to-link transition probabilities is proposed. The trip data are divided into three groups to reflex the traffic conditions according to the departure time, namely morning peak, evening peak and off-peak; the trip data are further processed according to the zone of departure and the zone of destination, addressing the issue that there are not enough trip data for the given origin-destination. Based on the assumption that the optimal route is chosen by the experienced users, the link- to- link transition probabilities are calculated by the historical trajectories, and the Markov chain is established to simulate the link choice behavior. The route with maximum probability is suggested as the optimal route, and a calculation method is proposed. Only the historical trip data is utilized to find the optimal route by the proposal method, avoiding the complicated calculation of the link travel time. The method demonstrates the advantages of easy acquisition of data, high consistency with the actual behaviors, and low computation requirements. The case study indicates that the accuracy of proposal method may vary according to the departure time, but the sizes of traffic zones have tiny impact.

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    Driver's Perception-Decision-Control Model
    FENG Shu-min, HUANG Qiu-ju, ZHANG Yu, ZHAO Hu
    2021, 21(1): 41-47. 
    Abstract ( )   PDF (1660KB) ( )  

    This paper proposes a Hidden Markov Model (HMM) based driver perception- decision- manipulation behavior model to simulate the car- following behaviors. The HMM model is used to describe driving intention and simulate the driver's perception process, that is, to obtain the desired vehicle spacing. The prediction module is developed to predict the vehicle trajectory responding to the traffic conditions and driver's psychological status. The prediction module represents driver's decision- making process. The optimization module simulates driver's control actions and adjusts the predicted vehicle spacing to meet the expected vehicle spacing. Driver's perception- decisioncontrol behavior is then simulated through a rolling process of the three proposed sub-modules. The natural driving data were used for empirical analysis and the results indicate the average error of the model is 1.47%, which reflects the effectiveness and accuracy of the model. This paper provides a new perspective for the theoretical research and application of driving behavior modeling.

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    Analysis and Identification of Drivers' Difference in Car-following Condition Based on Naturalistic Driving Data
    LIU Zhi-qiang, ZHANG Kai-duo, NI Jie
    2021, 21(1): 48-55. 
    Abstract ( )   PDF (2093KB) ( )  

    To study the behavior characteristics and identification of individual drivers in car-following condition, the differences in the distribution of car- following characteristics, including acceleration, relative speed, relative distance, time to headway (THW), time to collision (TTC), were compared based on naturalistic driving data by statistical analysis, frequency domain analysis and time- frequency analysis. The key features that characterize the difference in drivers' car- following behavior were extracted using statistical methods and discrete wavelet transform (DTW). A driver identification model based on Random Forest (RF) was established by using different parameters as the input vectors and determining the best parameters. The results of the naturalistic driving data from 8 drivers show that RF model with mean, standard deviation, median, and wavelet energy entropy of the acceleration, relative speed, relative distance, THW, TTC as feature vectors has an accuracy of 96.81% and an out- of- bag error rate of 4.55% in driver recognition. Compared with Support Vector Machine (SVM), K-Nearest Neighbor (KNN), and BP Neural Network, RF model established by multi- scale feature vectors is effective to obtain higher recognition accuracy in driver identification under the car-following condition. This result is important for the refined research of driving behavior and the development of personalized driving assistance systems.

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    Degradation of Urban Intersection Traffic Control Model
    ZHANG Li-li, ZHAO Qi, WANG Li, LIU Jian-dong, ZHANG Ling-yu, LI Kai-long
    2021, 21(1): 56-61. 
    Abstract ( )   PDF (1585KB) ( )  

    Though the intersection signal control model performs well in theory, it often has a model mismatch problem in practice. In response to this problem, we propose the concept of model degradation of the signal control model. An intersection signal control model with multiple control variables is first developed. The degraded path is then proposed based on the causal analysis of model degradation. Finally, the comparisons between the typical control strategies of each stage in the signal control model degradation are developed by using an online traffic simulation platform. The results show that the advanced control strategies can better respond to the changes in the intersection capacity coefficient when the intersection is oversaturated. However, with the aggravation of model degradation, the control effect of the intersection gradually decreases, which shows the feasibility and effectiveness of the model degradation concept proposed in this paper.

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    Single-point Signalized Intersection Operation Efficiency Evaluation Method Based on Trajectory Data
    CAI Xiao-yu, LV Liang, LU Kai-ming, TANG Xiao-yong, GAO Zhi-gang
    2021, 21(1): 62-68. 
    Abstract ( )   PDF (1865KB) ( )  

    The existing method for signalized intersection operation efficiency evaluation is mostly theoretical and not practical. This paper proposes a method to evaluate vehicles' performances at signalized intersections including queue length, travel time, number of stops, etc. The study collected multi-source GPS trajectory data of taxi, bus and driving map (car network). and obtained continuous speed change characteristics and position information of vehicle deceleration, stop and acceleration. The performance evaluation takes the operation status of the signalized intersection, as the first-level indicator and the average vehicle travel time, the 95 percentile queue length, and the frequency of cycle failure as the second- level indicators. Based on the Gaussian hybrid clustering model, the study graded and quantified the comprehensive performance measures and determined a five- level of service evaluation criteria. The example analysis shows that the method is able to accurately reflect the performances of the turning movements, approaches, and overall operation level of the intersection during different time periods. The relative error of the maximum queue length calculated from the proposed method and the queue length in the field is about 15%, which is smaller than what obtained from the simulation. Except for some cases of insufficient samples, the level of service evaluation results is closer to the actual operation than the simulation. The example analysis verifies the technical feasibility of the proposed method and the accuracy authenticity of the evaluation results.

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    Vehicle and Non-motorized Vehicle Traffic Conflict Recognition at Signalized Intersection Based on Vehicle Trajectory
    LONG Ke-jun, ZHANG Yan, ZOU Zhi-yun, GU Jian, HAO Wei
    2021, 21(1): 69-74. 
    Abstract ( )   PDF (1460KB) ( )  

    This study investigated four typical signalized intersections in the downtown area of Changsha, and then used video trajectory tracking software to extract the conflicting trajectory data of right-turning vehicles and through movement non- motorized vehicles. Based on the risk- avoidance behaviors such as decelerating, lane changing and likely colliding (the time from the collision point is less than 2 seconds), the study collected 254 samples of vehicle and non-motorized vehicle traffic conflicts. To improve the traditional conflict recognition model, this study selected the maximum time to collision (MTTC) and the time difference to collision (TDTC) as the evaluation index, and proposed a modified TTC (Time To Collision) model to identify the vehicle and non- motorized vehicle conflict. A real intersection was then used for the empirical study. The number of traffic conflicts calculated by the TTC model, the modified TTC model and the post encroachment time (PET) model were 7, 24, and 22, respectively. The results indicate that the traditional TTC method underestimates the level of conflict between vehicles and non- motorized vehicles at intersections. The accuracy rate of improved TTC method is increased by 2.14 times, which proves the feasibility of the proposed method.

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    Real Time Estimation of Bus Loading Rate Based on Bus Electronic Payment Data
    WEI Qing-bo, SU Yue-jiang, GAO Yuan, YANG Jing-feng, MO Jun-jie
    2021, 21(1): 75-81. 
    Abstract ( )   PDF (2372KB) ( )  

    Monitoring and scheduling bus operations require real- time grasping of bus loading rate. However, it is normally difficult to obtain the information of passenger drop-off stations in the one-ticket payment system. This study developed a portfolio model to estimate passenger's origin-destination (OD) station after passenger boarding the bus, and then performed the real-time estimation of vehicle loading rate using integrated multi- source data. The portfolio model is based on K-nearest-neighbor algorithm. Considering that there are still portion of passengers whose drop-off station are hard to be estimated, this study used a travel-area-estimation algorithm to obtain passengers' travel rules in a larger spatial dimension. This method effectively improved the estimating rate and utilization rate of historical data. In the occasional case that some historical data of passengers are missing, the study utilized the prior probability of dropoff flows at stations to perform the full sample estimation of passenger's OD in electronic payment system. A carfollowing survey was then used to verify the estimation result of different bus lines and shifts. It shows that the estimated bus loading rate is consistent with the actual results, which reflects the changes of the bus loading level.

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    Traffic Flow Parameters Estimation Based on Spatio-temporal Characteristics and Hybrid Deep Learning
    ZHANG Wen-song, YAO Rong-han
    2021, 21(1): 82-89. 
    Abstract ( )   PDF (1863KB) ( )  

    To explore the spatio-temporal characteristics of traffic flow and improve the estimation precision, this paper proposes a hybrid deep learning method for traffic flow parameters estimation. The input matrix was constructed by the traffic flow data obtained from the subject and upstream sections. The convolutional neural network (CNN) was used to capture the spatial characteristic of traffic flow, and the long short-term memory (LSTM) and gated recurrent unit (GRU) neural networks were used to analyze the temporal characteristic of traffic flow. Then, the outputs obtained from these three deep learning methods were integrated to obtain the estimated values of traffic flow parameters. The proposed method was verified using the field data from Hefei city of Anhui province, China and Sacramento of California, United States. The results indicate that the proposed method produces higher accuracy and reliability than existing methods, and reduces the estimation error by 5.72% to 33.29%. The hybrid method can provide high-quality basic data for the intelligent transportation system operation and management.

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    Vessel Trajectory Prediction Considering Difference Between Heading and Data Changes
    GAO Tian-hang, XU Li, JIN Lian-jie, GE Biao
    2021, 21(1): 90-94. 
    Abstract ( )   PDF (1536KB) ( )  

    Automatic identification system (AIS) data can reflect the specific dynamic of the ship at the current moment in real time, and the existing BP (Back Propagation) neural network based methods for ship trajectory analysis and prediction only take the heading data into the model directly. The methods do not consider the large deviation between the actual direction change range and the data change range when the ship heading changes near zero. In order to solve this problem, a ship AIS trajectory prediction model based on the improved neural network algorithm is constructed in this paper. The model introduces the double trigonometric function transformation on the basis of BP neural network. The sine value and cosine value are included in the model to consider the two-dimension direction of the heading. The inverse trigonometric function transformation and average processing are carried out to postprocess the predicted data. By selecting the case data to verify the model, the case results show that the prediction error of the model is smaller than the method without considering the difference, which greatly reduces the error range and can be more accurate for ship trajectory prediction.

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    Collaborative Optimization of Railway Timetable and Capacity Considering Customized Trains
    LI Xiao-juan, SHI Jia-na, LI De-wei, YAN Zhen-ying
    2021, 21(1): 95-100. 
    Abstract ( )   PDF (1833KB) ( )  

    Based on survey data, this paper proposes the passenger's travel probability function for different time periods and analyzes passenger's specific needs for customized trains such as the expected operation time and the type of seats. An alternative set of customized trains was established with the constraints of demand, stop and operation time. Then a bi-level collaborative optimization model was developed to maximize the enterprise profits while keep the remaining available capacity as the maximum when adding customized trains. The particle swarm optimization algorithm was used to solve the model. Then, a timetable was obtained with the consideration of the customized trains and the adjustment cost and capacity utilization of existing trains. The Hohhot-Wuhai railway line in Inner Mongolia, China was analyzed as an example. It was found that the operation of customized trains is affected by the adjustment cost of existing trains. The operation of customized trains also affects the overall layout of timetable and remaining available capacity of trains.

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    Determining Special Train Timetable in Epidemics for Beijing Metro
    SU Shuai, LIU Xu, WANG Xue-kai, TANG Tao, CAO Yuan
    2021, 21(1): 101-107. 
    Abstract ( )   PDF (2751KB) ( )  

    This paper presents the designing method of the special train timetable with high demands under unusual conditions like epidemics. Considering the designing process of the special train timetable, this paper proposes a bilevel programming optimization model to reduce vehicle's loading rate with high demand. The upper model optimizes the operation plan based on the distribution characteristics of passenger flow in time and space. The lower model optimizes the parameters of train timetable which include the cycle time, dwell time, running time between stations and turn-back time. The optimization problem for the special train timetable can be linearized and then solved iteratively using CPLEX solver. The effectiveness of the proposed optimization method is verified through the data of YIZHUANG line of Beijing Metro. The simulation results show that the maximum train loading rates for inbound and outbound directions are reduced by 21.1% and 16.6% respectively during the morning peak when all available trains are operated for the line. The maximum train loading rates for the inbound and outbound directions are also reduced by 23.2% and 32.3% during the evening peak. The proposed approach can be used to support the urban rail transit timetable creation during the epidemics.

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    Passenger Flow Distribution of Regional Multi-standard Rail Transit Based on Passenger Route Selection
    NI Shao-quan, YANG Hao-nan, PENG Qiang
    2021, 21(1): 108-115. 
    Abstract ( )   PDF (1368KB) ( )  

    To quantify the impact of passengers' transfer on their travel route selections, this study added virtual transfer stations to the single-layer network, and developed a three-layer multi-standard rail transit topology network model without hidden connections. The connectivity coefficient between networks was calculated based on the time and transfer node connectivity. A function was established to describe the passenger's familiarity to the line network. In this function, the Dijkstra method was used to search for the K short path between the start and end points of the model, and the time was determined in consideration of passengers' travel plans and the complexity of the line network from the passengers' perspectives. A generalized travel cost function was also established to reflect the factors affecting the passenger path selection. The Logit model was used to calculate the selection probability for each route. The passenger flow distribution algorithm was designed to solve the model and then complete the passenger flow distribution to the multi-standard rail transit network. The multi-standard rail transit network simulation model was based on the Chengdu Metro, Chengguan, Chenggui High-speed Railway lines, etc. The passenger flow distribution examples analysis show that the passenger flow distribution results are basically consistent with the actual data, which confirms the authenticity and effectiveness of the passenger flow distribution algorithm.

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    Impact of Curve Radius and Spiral Length on Steering Behavior on Two-lane Highway
    YUAN Fang, YANG Zhen, ZHOU Xiong-feng
    2021, 21(1): 116-123. 
    Abstract ( )   PDF (2004KB) ( )  

    To identify the factors that are closely related to driver's steering behavior on the spiral segment of a twolane highway, this study performed driving simulation experiments and collected steering wheel angle data from 15 drivers on 72 curves with different curve radius, turning direction, and spiral length. The Wavelet transform was used to decompose the spatial sequence of steering wheel angle signal. Then a co-relation analysis was conducted to examine the variation of natural steering behavior and trajectory correction behavior under different curve radius and spiral length conditions. The results show that natural steering distance at entrance spiral is significantly affected by curve radius and spiral length, but the natural steering distance is not affected by the turning direction. At entrance spiral, drivers are less sensitive to the route radius change when the curve radius increases. For the trajectory correction behavior, the average swing amplitude of steering wheel decreases with longer spiral length when radius is fixed. However, the rotation rate of steering wheel for correction appear to increase with longer spiral length. The average swing amplitude and rotation rate of steering wheel for correction at exit spiral are higher than those at entrance spiral. When the length of spiral is close to the natural steering distance, the average swing amplitude of steering wheel and the rotation rate are both at low levels. Therefore, it is reasonable to take the natural steering distance as the ideal spiral length.

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    Lane-level Travel Time Estimation Method Based on Lane Change Trajectory Planning Model
    GUAN De-yong, ZHANG Shu-peng, LIU Hai-qing
    2021, 21(1): 124-131. 
    Abstract ( )   PDF (2108KB) ( )  

    In the context of the Internet of vehicles, to satisfy the requirements of precise vehicle guidance, a lane-level travel time estimation method is proposed based on a lane change trajectory planning model. Firstly, the lane- level topology model of road networks is established, and the Link division is carried out. An improved quintic polynomial is used to model the vehicles' travel trajectory, and the lane change trajectory planning model is constructed for the vehicle trajectory between links of different sections. Then, the travel trajectory and travel time of each Link in the road section are integrated to estimate the lane-level travel time. Finally, a four-lane road is selected as an example in the VISSIM simulation to verify the performance of the proposed method. The simulation results show that, compared with the traditional travel time estimation method, the improved quintic polynomial lane change trajectory planning model can accurately obtain the travel trajectory with the shortest travel time and realize the accurate estimation of lane-level travel time under different vehicle speeds.

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    Influencing Factors of Driving Attention Demand in Urban Road Scenario
    LIU Zhuo-fan, ZHAO Xia, WU Fu-wei
    2021, 21(1): 132-136. 
    Abstract ( )   PDF (1461KB) ( )  

    To explore the influencing factors of driving attention demand in urban roads, scenarios with various traffic variables were built. And 30 participants were tested on driving simulators for vision occlusion. The driving attention demand level is expressed by the vision occlusion probability. Stepwise logistic regression method is used to establish driving attentional demand level, and the impact of each variable is analyzed. The results show that the occlusion probability fluctuates greatly along the driving route. Different traffic variables require different amounts of driving attention. Specifically, intersections, bus stops, roadside parking cars, headway, meeting distance and road curvature are the most significant factors affecting driving attentional demand. The occlusion probability becomes lower when close to an intersection, and there is almost no occlusion after reaching the intersection. It indicates that drivers actively adapt to the attention demand of driving scenario, selectively obtain traffic variable information related to current driving, and predict the development trend of each traffic variable. The results can help improve the scenario sensitivity of driving distraction warning system.

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    Driver's Visual Search Ability in Sub-task
    QIN Hua, LI Ji-tao, RAN Ling-hua
    2021, 21(1): 137-141. 
    Abstract ( )   PDF (1336KB) ( )  

    This article investigates the impact of sub-tasks on driving performance by evaluating driver's visual search ability. The driving takeover performance is reflected by driver's reaction time, and driver's visual search ability is evaluated by visual field test and eye movement data. The independent variables are defined as the type of sub-task undertaken by the driver and the length of time of the sub- task. The reaction time and eye movement data were collected from a total of 32 participants under different levels of immersion. The results show that after certain reaction time, participants performed with shorter response time and higher accuracy than the sub-task just started. The types of the sub-task undertaken by the participants have significant impacts on their visual search ability. Compared to the group with the sub-task of game, the participants in the group of cross-talk sub-task reacted faster and performed with higher accuracy. In addition, the immersion time of 5 minutes or 10 minutes had no significant impact on participant's visual search ability.

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    Analysis and Modeling of Drivers' Visual Characteristics at Entrance and Exit of Undersea Tunnel with Coupling of Illuminance and Longitudinal Slope
    PAN Fu-quan, PAN Hai-tao, WANG Zheng, ZHANG Li-xia, MA Chang-xi, YANG Jin-shun
    2021, 21(1): 142-148. 
    Abstract ( )   PDF (1981KB) ( )   PDF(English version) (764KB) ( 62 )  

    To analyze drivers' visual characteristics at the entrance and exit of undersea tunnel, this study carried out the real vehicle test with 26 drivers operating in the off peak period under similar traffic conditions. The data of illuminance, eyelid closure, gaze duration, vehicle speed and position were collected using the vision instrument and illuminance meter under the real traffic condition. The change rules of eyelid closure, gaze duration and driving speed were analyzed under the coupling effect of different illuminances and longitudinal slopes. The mathematical models were proposed to describe the co- relations between eyelid closure, gaze duration, driving speed and illuminance and slope. The results show that: when driving through the entrance and exit section of the undersea tunnel, (1) driver's eyelid closure is significantly reduced, and the illuminance has significant impact on eyelid closure; (2) the fixation time is increased, which is significantly affected by illuminance; (3) the fixation points are mostly distributed on the front vehicles; (4) the vehicle speed shows a trend of decline- rise, then keep steady, and then decline-rise. The illuminance and longitudinal slope also have significant impact on vehicle speed.

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    Commercial Truck Driving Risk Evaluation Based on Artificial Immune Mechanism
    HU Li-wei, HE Yue-ren, LI Yao-ping, MENG Ling, YIN Xiu-fen
    2021, 21(1): 149-155. 
    Abstract ( )   PDF (1743KB) ( )  

    This study evaluates driving risks of commercial trucks to prevent traffic accidents and to monitor commercial trucks in real-time to improve the transportation safe. From the traffic accidents investigation reports, the study calculates the frequency of driving risk factors relevant to truck traffic accidents, extracts the key factors of commercial truck driving risks and establishes a driving risk indicator system for risk evaluation. The study applies the signal processing mechanism of the artificial immune danger theory and the improved dendritic cell algorithm to the commercial truck risk assessment, which uses the level value of the risk evaluation index as the antigen vector. The driving risk evaluation model is then developed based on dendritic cell algorithm, and the commercial truck data from a transportation group in Yunnan Province was used as the empirical analysis. The results indicate that the high driving risk of commercial trucks is usually the effects of multiple factors. The proposed model is able to evaluate the driving risks of commercial trucks using the real-time data from the monitoring platform. The model is reliable and effective, and produces high accuracy rate and low false alarm rate. It also provides a basis for the prevention and management of commercial trucks driving risks.

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    Revenue Adjustment for Highway Public-Private Partnerships Projects Considering Inflation Risk
    WU Zhen-yao, SHUAI Bin, ZUO Bo-rui
    2021, 21(1): 156-161. 
    Abstract ( )   PDF (1245KB) ( )  

    In order to study the risk of undervalued or overvalued inflation in highway PPP projects and the countermeasures, this paper proposes revenue adjustment methods, including revenue compensation and excess revenue sharing, based on the regular adjustment of toll. The methods consider the changes caused by inflation in both operation cost and the time value of money. The revenue adjustment can effectively ensure the income in the project when inflation is underestimated. It can also avoid the private sector to obtain excess income when inflation is overestimated, which will damage the social benefit. The net payment of the government on revenue adjustment is mainly affected by demand price elasticity and revenue adjustment share proportion. When the users' perceived price decreases, the elasticity of demand price and the net present value of the project increases, but the net payment of the government will decrease. With a larger proportion of revenue adjustment, the government shares a larger inflation risk, and its net payment will also increase.

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    Stop Selection of Limited-stop Bus Services Based on Multi-criteria Collaboration
    WU Qun-yong, WAN Yun-peng
    2021, 21(1): 162-168. 
    Abstract ( )   PDF (2406KB) ( )  

    There are two drawbacks in the existing methods on the stop selection of express bus services. One is that the pivotal role of bus stops is ignored, and the other is that the methods usually only consider bus passenger flow data but does not consider other data sources such as taxi. By introducing the complex network theory, this paper integrates the bus and taxi passenger flow data, and proposes a recommendation method of limited-stop bus stops based on multicriteria collaboration which comprehensively considers the passenger volume at bus stops, potential passenger flow and the pivotal role of bus stops. Firstly, based on the data of bus passenger flow, bus lines and taxi passenger flow, we calculate the bus passenger volume and potential passenger volume. Secondly, the importance degree of bus stops is calculated by constructing a directed-weighted complex network model of the urban bus system. Finally, the important degree of bus stops, passenger volume and potential passenger volume are weighted and summed to gain the comprehensive score of bus stops by analytic hierarchy process, and the recommendation method of the bus stop combination is constructed. Taking Xiamen as an example, the method is applied to conduct the bus stops recommendation. The results show that, with the introduction of the stop importance and potential passenger volume, the recommended stops are more suitable for the actual resident travel demand compared with the traditional methods.

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    Convenience Index of Public Transportation for Urban Tourist Attraction: Based on Investigation in Wuhan
    ZHU Shun-ying, DIAO Cheng-liang, XIAO Wen-bin, CHEN Qiu-cheng, WANG Hong
    2021, 21(1): 169-175. 
    Abstract ( )   PDF (2021KB) ( )  

    In order to compensate for the defect of subjective- objective separation in the evaluation on the public transportation convenience for urban tourist attractions, this paper took the factors of tourist's individual characteristic, public transportation travel chain and attractiveness of the tourist attraction as the independent variables, and the perceived convenience level of tourists as the dependent variable based on a single travel chain of each tourist. The questionnaire data from 15 major tourist attractions in Wuhan were collected to establish the Multinomial Logistic and Convenience Index (CI) model. The regression coefficient was used to analyze the influence of each factor, the standardized coefficient was used to analyze the influence weight of each factor on the perceived convenience level, and the CI model was used to calculate the convenience indices of public transportation for urban tourist attractions in Wuhan. The results show that: (1) There is a significant interaction effect between non-motorized travel distance and cycling sharing rate, and it is more suitable to walk when the non-motorized travel distance is less than 0.408 km. (2) Factors of public transport travel chain are ranked from the largest to the smallest according to their influence weight on perceived convenience level-positive influence: subway sharing rate, cycling sharing rate; negative influence: nonmotorized travel distance, transfer times, total travel distance, non-linear coefficient. (3) The public transportation convenience indices of different tourist attractions in Wuhan are different significantly, the Chu River Han Street's convenience index is highest and the East Lake Greenway-Mount Mo's convenience index is lowest.

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    An Accessible Bus Network with Uneven Travel Distribution
    GUO Chen, WANG Jian-jun, HUO Yue-ying, QIU Zhi-xuan
    2021, 21(1): 176-182. 
    Abstract ( )   PDF (1593KB) ( )  

    An accessible bus network is featured of good time and spatial coverage and reduced passenger travel time, which is helpful for traffic congestion mitigation. This study focuses on cities that has its downtown area located near the city boundary and the travel demand is unevenly distributed in the city area. Assuming the travel demand function is uniformly distributed in downtown area and linearly decreased in suburban area, this study develops a model for planning bus network and determining bus stations and departure frequencies. The model is not significantly affected by the decision variables and input parameters, and has good stability and feasibility. When the headway, the ratio of downtown area to the city area, and the stop spacing varied from -50% to 46%, the system cost would increase by less than 10% . The passenger access speed has a great impact on the system cost and the user cost. This indicates that promoting shared bicycles and bus microcirculation would significantly reduce the cost of bus travel. The more demand was concentrated in downtown, the bus agency would have significantly reduced operation cost. However, the stability of the bus network would see a decrease, which would also weaken the competitiveness of the bus.

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    Urban Bus Scheduling Optimization Based on Simulated Anneal-adaptive Cuckoo Search Algorithm
    LAI Yuan-wen, ZHANG Jie
    2021, 21(1): 183-189. 
    Abstract ( )   PDF (1360KB) ( )  

    In order to improve the operation efficiency of urban public transport, a public transport scheduling optimization model based on the Simulated Annealing- adaptive Cuckoo Search algorithm is proposed. With the passenger flow characteristics reflected by the actual passenger flow data of the route, a bus scheduling optimization model considering the interests of both the bus company and passengers is established. By improving the fixed step size of the Cuckoo Search algorithm and adding the annealing operation of the Simulated Annealing algorithm, the Simulated Annealing- adaptive Cuckoo Search algorithm is designed to improve its ability to jump out of the local optimal solution and find the global optimization in the optimization process. Finally, taking the No.125 bus line in Fuzhou as an example, the passenger flow characteristic data of this line is applied to the model and the solution algorithm. The results show that the results obtained by the model algorithm based on different stakeholder weights are better than the existing scheduling scheme, which verifies the effectiveness and practicality of models and algorithms.

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    Comparative Analysis and Prediction of Motor Vehicle Crash Severity on Mountainous Two-lane Highways
    YANG Wen-chen, XIE Bi-shan, FANG Rui, QIN Ya-qin
    2021, 21(1): 190-195. 
    Abstract ( )   PDF (1289KB) ( )  

    This paper developed the motor vehicle crash severity prediction models on mountainous two-lane highways using the partial proportional odds model and the ordered Logit model. Based on 1740 cases of motor vehicle crashes in Yunnan province, the crash data was classified as motor vehicle and motor vehicle crash, motor vehicle and motorcycle crash, motor and non- motorized vehicle crash. The accident severity was classified as property damage only, minor injuries, and serious injuries or fatal. The comparative analysis of the significant factors and the model prediction accuracy relevant to each severity grade was carried out. The marginal effect analysis was also performed to investigate significant variables of the partial proportional odds model. The results show that the impact factors for different accident severity are significantly different for different vehicle types. Compared to the ordered Logit model, the partial proportional odds model could be used to find the hidden variables that are not following the proportional odds assumption. The average prediction accuracy using the partial proportional odds model are respectively 78.29%, 73.63% and 72.04% for motor vehicle and motor vehicle crash, motor vehicle and motorcycle crash, and motor and non-motorized vehicle crash. The accuracy is respectively improved by 14.54%, 5.65% and 3.32% compared to the ordered Logit model. The study provides references for highway safety administrations to proactively prevent accidents and reduce risks.

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    Factors Affecting Electric Bicycle Rider Injury in Accident Based on Random Forest Model
    LI Ying-shuai, ZHANG Xu, WANG Wei-jie, JU Xiao-fan
    2021, 21(1): 196-200. 
    Abstract ( )   PDF (1260KB) ( )  

    This study analyzed the crucial factors that affect the injury degree of electric bicycle riders in the accident and ranked the factors based on their significance. The study collected electric bicycle traffic accident data in a city from 2013 to 2015, and then performed the descriptive statistical analysis. 22 factors related to the severity of traffic accidents were selected for analysis. The random forest model was used to predict the severity of electric bicycle rider injuries, and then rank the significance of the impact factors. The result indicates that the most significant factors affecting the severity of electric bicycle rider injuries in the accident are as follows: the type of accident, the injury is on which part of the body, and the separation type on the road, etc. The study also puts forward suggestions to improve bicycle rider's safety in terms of related factors, which provide reference for prevention of electric bicycle accident and relevant decision-makings in the safety management.

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    Numerical Analysis of Influence of Ship Listing on Evacuation Efficiency of Different Pedestrian Flows
    FANG Si-ming, LIU Zheng-jiang, FENG Shi-cheng, WANG Xin-jian
    2021, 21(1): 201-206. 
    Abstract ( )   PDF (1767KB) ( )  

    In order to analyze the impact of ship listing on the evacuation process on passenger ships, this paper established an improved social force model by incorporating incline force and self-adjustment force to consider the ship listing. The model was verified by comparing the results with previous experiments. The scope of individuals' vision was considered, and the effective ranges to the surrounding persons were determined in this model. MATLAB was used to simulate the pedestrian flow in four scenarios, i.e., one-way, bidirectional, cross and multi-directional scenarios. The influence of different list angles on the individuals' average speed was analyzed, and the law of time changing with the heel or trim angles were fitted. The results show that the pedestrian speed decreased slightly when the ship listing angle less than 15°; however, it has little impact on the overall evacuation process. But when the angle more than 15°, the speed dropped rapidly, yet the evacuation time increased sharply, and the relationship between time and listing angle is fitted by a sixth-order function. Overall, the best time to evacuate is that the listing angle less than 15°.

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    Optimal Model of Taxiway Scheduling Based on Time Margin Control
    JIANG Yu, TONG Chu, LIU Zhen-yu, HU Zhi-tao, XU Cheng, ZHANG Hong-hai
    2021, 21(1): 207-213. 
    Abstract ( )   PDF (1703KB) ( )  

    In practical situations, aircraft may have short remaining taxi time, which leads to low punctuality during airport surface operation. The taxiway scheduling optimization problem is studied in this paper. In order to control the taxi time of each aircraft, the dynamic priority is set mainly based on time margin, and also taking into account the aircraft fuel consumption and passenger load. The taxiway scheduling optimization model based on time margin control is established. The biogeographic algorithm is designed to solve the model. Simulation verification is conducted on a large domestic airport. The results show that, compared with the classic first- come- first- served strategy, the difference between the estimated time to complete the taxi and the actual time to complete the taxi (arrival error) decreases from 1499 s to 553 s with a reduction of 63.1% and the conflicting aircraft arrival error decreases from 371 s to 147 s with a reduction of 60.3%. In terms of conflict relief, the aircraft with a greater time margin has taken on more conflict waiting time, effectively reducing the number of aircraft taxi conflicts. It guarantees the smooth progress of gate assignment and runway scheduling. The taxiway optimization model based on time margin control improves the punctuality of the aircraft, effectively reduces taxi conflicts, and improves the operation efficiency of the airport surface. It can provide a theoretical basis and decision-making references for traffic control of the busy airports.

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    Signalized Intersection Pedestrian Crossing Design Speed and Elderly Pedestrian Proportion Relationship Study
    ZHANG Hui-ling, XI Bang-shun
    2021, 21(1): 214-220. 
    Abstract ( )   PDF (1748KB) ( )   PDF(English version) (992KB) ( 53 )  

    This study investigates the relationship between pedestrian crossing speed and the elderly pedestrian proportion under different pedestrian flow conditions. The micro simulation model was used to obtain the crossing speed and elderly pedestrian proportion data considering different pedestrian level of services (PLOS). The pedestrian free-flow speed and accelerations for the old people, the young and middle-aged people were collected at three signalized intersections in Chongqing, China to calibrate the micro-simulation model. The relationship between the elderly pedestrian proportion and the pedestrian crossing design speed was established by the principal component analysis and the regression model. The results indicate that the design speed of pedestrian crossing is 0.94 m ⋅ s-1 when the elderly pedestrian accounts for 21% to 41% of the pedestrian flow. The design speed of pedestrian crossing is recommended to be 0.86 m ⋅ s-1 when there are more than 41% of pedestrians are elderly people, which meets the needs of the elderly crossing at signalized intersections.

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    Risk Assessment and Influencing Factors of Pupils' School Commuting Accident Risk in School District Scale
    JI Xiao-feng, ZHANG Qi
    2021, 21(1): 221-226. 
    Abstract ( )   PDF (1512KB) ( )   PDF(English version) (737KB) ( 77 )  

    This paper proposes a risk assessment method of school commuting accident and identify the crucial influencing factors, by integrating traffic accident data, road operation data and school district zoning data, the study developed the accident assessment method and analyzed the influencing factors using the random forest model. With the assumption that pupils' school commuting is within the school district, a road exposure model was developed through traffic accident data and road length data to evaluate the pupils' school commuting accident risk. A verification analysis was conducted by taking the central city of Shenzhen as an example. The results show that: the high- risk school districts in the central city of Shenzhen are mainly in the north of Nanshan and Luohu, while the low-risk school districts are mainly distributed in the south-central part of Nanshan and the central part of Futian. The risk assessment model based on the random forest produced 85.93% prediction accuracy. Which shows the performance of the proposed model for the pupils' school commuting accident risk assessment. Primary school density and school district zoning area are two major influencing factors of pupils' school commuting accident risk, which can explain respectively 37.15% and 22.86% of school commuting accident risks.

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    Analysis of Passenger Car Preference Based on Panel Data
    YANG Ya-zao, LI Quan-sen
    2021, 21(1): 227-232. 
    Abstract ( )   PDF (1472KB) ( )  

    Based on the panel data of passenger car sales in China from 2009 to 2019, combined with vehicle characteristics, the Logit model is constructed to analyze the response of vehicle characteristics evolution to consumer demand, and to compare the consumer preferences of passenger cars in China and Switzerland. The results show that the market share of passenger cars with higher engine fuel efficiency and power is higher. Heavy vehicles are more favored by Chinese consumers than light vehicles. The marginal value of fuel efficiency is smaller in the high-power vehicle segment, that is, consumers who are most likely to produce more pollution emissions are less sensitive to vehicle fuel efficiency. And they are still in the stage of the rapid popularization of passenger cars. There are obvious differences in consumer preferences between China and Switzerland, which is in the stage of multiple ownership (more than 250 vehicles per thousand people). Chinese consumers' preference for fuel-efficient, high-power, and heavy-duty passenger cars is gradually deepening, while Swiss consumers' preference for fuel-efficient, high-power, and lightduty vehicles is gradually decreasing.

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