2015 No. 5

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2015, (5): . doi: 10.3963/j.issn.1674-4861.2015.05.001
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2015, (5): . doi: 10.3963/j.issn.1674-4861.2015.05.002
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Research trends of transportation safety:identified from ESREL 2015 conference
YAN Xinping, ZHANG Di, ZHANG Mingyang, FU Shanshan
2015, (5): 1-8,15. doi: 10.3963/j.issn 1674-4861.2015.05.001
Abstract(402) PDF(2)
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This paper provides an overview of the 25 th European Safety and Reliability Conference (ESREL 201 5). Through statistically categorizing the keynote speeches and technical papers,from a perspective of systems security ap-proach,popular topics in the field of safety and reliability including resilience theory,safety assessment theory and uncer-tainty theory are summarized in this paper and their applications in the field of transportation system are introduced.Fi-nally,the trend of risk prevention and control of the transportation system based on the popular topics presented at the ESREL 201 5 are illustrated and a safety assessment framework of transportation system based on the resilience theory is presented.
An Analysis of Traffic Chaos on Urban Expressways under Variable Speed Limits
GU Jian, CHEN Shuyan
2015, (5): 9-15. doi: 10.3963/j.issn 1674-4861.2015.05.002
Abstract(334) PDF(0)
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Variable Speed Limit (VSL)strategies have been used to manage traffic operation in urban expressway systems.To develop a reasonable speed limit values,the characteristics of traffic flow and speed should be taken into con-sideration.In this paper,traffic chaos on urban expressways is analyzed due to speed variation resulting from using VSLs. The ratio of vehicles complying with VSL in flow,p ,is applied as the key parameter to analyze the speed characteristics. A section of 3 rd Ring Expressway in Beijing is simulated using Vissim.The C-C method is used to reconstruct the phase space based on the speed time series data collected from Vissim scenarios.Small Data Set method is used to identify the traffic chaos by calculating the largest Lyapunov exponentsλmax .Traffic operations were compared between the scenarios with and without the implementation of VSLs.Analysis results showed thatλmax of speed time series is positive without VSL,andλmax of speed time series is also positive at the location 200 m downstream of VSL sign and a quadratic regres-sion model is found to fit betweenλmax and p .The minimum value ofλmax reached 0 when p =76.8%.The results of this paper can be useful to support the decision-making of the speed limits and implementation of the VSL strategies.
A Study on Optimization of Urban Transit Systems under a Low-Carbon Mode
WANG Renjie, WEI Yannan, XU Lunhui
2015, (5): 16-22. doi: 10.3963/j.issn 1674-4861.2015.05.003
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With the low-carbon mode gradually gets people′s attention,it is imperative to establish a low-carbon, environmental,low-consumption,efficient and safe mode of transportation systems.Existing studies in China and abroad focused on the target of using energy consumption or passenger turnover quantity to optimize the transportation structure. The study develops a low-carbon and optimization model for urban transit systems with the use of carbon footprint calcu-lation formula.Taking the minimum carbon footprint per capita and maximum urban transit system efficiency as the tar-gets,and using travel demand of citizens,developed urban energy consumption limits,accessibility of residents and transport capacity of all kinds of transportation modes as the constraints.The public transit systems of Beijing in 2020 are optimized using this model.The results indicate that the efficiency of new public transit systems is better than the tradi-tional one,and per capita carbon footprint drops 5.965 g/person,which is 13.7% less than the traditional one.The study results demonstrate the feasibility of optimizing the urban public transit systems through low-carbon mode.It will also en-courage the cities to adopt a low-carbon mode for their public transit systems.
A Method of Determining the Demand of City Chauffeured Car Service Based on the Ordinal Utility Theory
LI Linheng, LI Zongping, CHEN Qian
2015, (5): 23-28,35. doi: 10.3963/j.issn 1674-4861.2015.05.004
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As an advanced type of taxi appears in everyday life,the chauffeured car service provides a service similar to the dial-a-ride service.In order to improve the quality of chauffeured car service,it is necessary to investigate the de-mand of the chauffeured cars in a city.This paper assumes that the total number of taxis in a city is composed of the regu-lar taxis and extended chauffeured cars.The number of chauffeured cars and regular taxis is allocated according to the or-dinal utility theory in economics,and thus the demand of chauffeured car service in a city is determined.The numerous example analyses indicate the proposed method is feasible.This method not only expands the method of determining the quantity of taxis required in a city,but also provides a tool for the planning and design of operation routes,real-time scheduling and dispatching for.
Fruit and Vegetable Distribution with Soft Time Windows Based on an Improved Genetic Algorithm
LI Peiqing, HE Jie, HUANG Yongsheng, FAN Chenhao, GAO Haidan
2015, (5): 29-35. doi: 10.3963/j.issn 1674-4861.2015.05.005
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In order to investigate the impacts of vibration,shock and collision on fresh fruits and vegetables during transportation,an improved genetic algorithm model is developed based on the soft time windows,pavement roughness and road grades.The objective of this model is to minimize the delivery costs of the suppliers by improving objective func-tion,fitness function and crossover operator.Furthermore,comparison analyses are conducted among improved genetic algorithm,original order crossover (OX)genetic algorithm and group-order crossover genetic algorithm with a focus on the transport routes of fresh fruits and vegetables among 13 cities in the Jiangsu province as a case study.The results indi-cate that the proposed model provide 1 5.3% higher accuracy of delivery cost estimation over the conventional models.
A Transit Priority Model for Arterial Roads Based on the Delays of Upstream and Downstream Intersections
LI Zhenlong, ZHU Minghao, WAN Baoju, LIAN Peikun, DONG Wenhui
2015, (5): 36-42. doi: 10.3963/j.issn 1674-4861.2015.05.006
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The coordination of green-wave and the efficiency of downstream intersections are affected by the transit signal priority (TSP)set up at the upstream intersections.In order to address this issue,a TSP model that considers the delays at the upstream and downstream intersections along arterial roads is presented in this paper.The extension of green light phase and the reduction of red light phase are used in the model.The weighted delays of upstream and downstream intersections are used as the performance index.This model ensures the transit priority and reduces its impacts on green-wave coordination.It is validated by Vissim simulation in this study.The results show that the average vehicle delay at down-stream intersections decreases by 10%,although the average vehicle delay at upstream intersections increases by 2.6%.The weighted delay of upstream and downstream intersections decreases by 3.7% comparing with the isolated TSP control strategy.The study results clearly show that the strategy in the proposed model can reduce the conflict between the TSP and the green-wave coordination.
A Study of Traffic Oscillations at the Bottlenecks on Urban Expressways
ZHANG Juan
2015, (5): 43-48. doi: 10.3963/j.issn 1674-4861.2015.05.007
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Traffic oscillations at the typical bottlenecks (on-ramp,off-ramp)on the expressways of Shanghai are in-vestigated.A method of cumulative movement sequence,which is based on comparisons between cumulative values for a long term and mean values for a short term,is used.The features of the traffic oscillations including propagating speeds, amplitudes and the relationships among amplitudes,moving step size and background speeds are analyzed.It is found that the oscillations arise in the downstream part of the queue at a bottleneck and propagate to the upstream with a nearly con-stant speed of about 20~25 km/h.Under different moving step size,the correlation coefficient between the amplitude of an oscillation and the moving step size at 2 types of bottlenecks are 0.964 2~0.999 8 and 0.982 2~0.999 4,which shows a high positive correlation.No significant correlation is found between the amplitude of an oscillation and the background speed.Finally,study results also indicate that the layout of road infrastructure plays an important role in amplifying or impairing the amplitude:the amplitude is amplified when the oscillation crossed a diverging ramp,but the opposite result is shown on a merging ramp.The study results of this paper could provide a basis for designing on-ramp control algorithm for expressway bottleneck areas.
A Network Reliability Evaluation Method for Airport Collection and Distribution
HUA Songyi, BAO Danwen, ZHAN Xuren
2015, (5): 49-54. doi: 10.3963/j.issn 1674-4861.2015.05.008
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In order to evaluate the reliability of airport collection and distribution,the differences of node impor-tance and road classes are analyzed,which shows that the connections of the network of airport designated roads and serv-ice roads differs from their urban counterpart.Therefore,edge weights are given based on feature index algorithm of the traditional complex network,and an improved complex network model is proposed.The model is verified by through sim-ulation tests,combining with a case study for the road network of Beijing Capital Airport.The results show that the de-gree distribution of traditional complex network model obeys the Poisson distribution,while the improved complex net-work model follows the power-law distribution,which fits the scale-free property of airport road network better.Moreo-ver,the cluster coefficient of the improved complex network model is 0.01 5,only 20% of the traditional complex network model,and the average weighted length is 10.38,which is 1.1 5 longer than the average path length.It fits the functional classification of airport roads,but the scale-free property is not significant.It is also found through the attacking simula-tions that node strength is more important for network reliability than the node degree,and the reliability of airport road network can be effectively improved by enhancing the protection of this type of nodes.
A study of the Speed Limits under the Ice and Snow Conditions for Urban Expressways
LI Songling, XIANG Taotao
2015, (5): 55-61,77. doi: 10.3963/j.issn 1674-4861.2015.05.009
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In order to improve traffic safety on urban expressways under the ice and snow,the effects of traffic vol-umes,vehicle types and lane positions on vehicle speed are investigated,where traffic flow data is collected from video re-cording and manual investigation in expressways in Harbin.Based on the characteristics of the critical condition of vehicle rear-end collision and vehicle-following,a speed limit model is developed,including variables of the road friction coeffi-cients and traffic volume,etc.The parameters of this model are calibrated using the surface friction coefficients under dif-ferent conditions of ice and snow,and the focus is to study the effects of ice and snow on the speed limit of urban express-ways.Finally,a method for optimizing speed limits by traffic volume levels is proposed.The study results showed that the speed limits determined by the proposed model could meet the requirements of vehicle safety on urban expressways under the condition of ice and snow.The speed limit is getting lower in a descending order of snow,ice,and ice film,but it can be increased by 10~20 km/h after the snow is cleaned.The speed limits for individual lanes and different types of vehicles should be set up differently on urban expressways under the ice and snow conditions,and the differences of speed limits between adjacent lanes should be within 5~10 km/h as well as between small and large vehicles.The speed limits should be set up according to different levels of traffic volumes under ice and snow conditions,including less than 800 pcu/h,800~1 500 pcu/h,and more than 1 500 pcu/h,which will increase the efficiency of transportation systems.
A Study of Deceleration Driving Behaviors at Upstream Functional Areas of Unsignalized Intersections
ZHENG Yuan, ZHANG Guoqiang, QI Yuli
2015, (5): 62-70,77. doi: 10.3963/j.issn 1674-4861.2015.05.010
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In order to study traffic safety and efficiency at upstream functional areas of unsignalized intersections, the decision-making process and its influential factors of driving behaviors before entering into intersections are studied. The data is collected by video in Nanjing,China.The speed and deceleration of decelerating driving behaviors are extrac-ted,and their features are quantitatively analyzed.A variance analysis method is used to estimate the degree of influence of each influential factors on the speed and deceleration,and a model of driving behaviors between deceleration and influ-ential factors is developed.The results show that,the speed of vehicles has an obvious downtrend at upstream functional areas of unsignalized intersections,and speed distribution gradually changes from discrete to centralize.The changing process of vehicles'deceleration is from large to small.The initial speed (V A0 )and left/right steering rotation angle are selected,and have significant effects on the model.The study provides constructive suggestions and theoretical basis to improve intersection design,traffic policy and the safety.
Effects of Emergency Turning on the Rollover of Coach Buses under High Speeds
ZENG Cheng, WU Chuna, MENG Xingkai, WANG Yiying
2015, (5): 71-77. doi: 10.3963/j.issn 1674-4861.2015.05.011
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In order to study the effects of different emergency steering on driving safety,Trucksim software pack-age is used to simulate its impact and the tire load transfer rates (LTR )of coach buses were analyzed.After a vehicle dy-namics simulation test under multiple sets of road conditions,the effects of emergency steering under various driving speeds and steering operations on bus rollover are quantitatively analyzed.The simulation results show that the driving speed and steering rotation angle are negatively correlated with bus stability on dry pavements.The higher the speed,the greater the steering rotation angle,and LTR is closer to 1.The driving speed and steering extent are negatively correlated with bus skid stability on wet pavements.The higher the speed,the greater the steering extent,and the more the buses inclined to sideslip.In addition,the rollover risk or sideslip risk of the second turning is significantly higher than the risk of the first one.
A Method of Optimizing the Locations of Flooding Emergency Resource Stations
WANG Shuwei, ZHOU Ronggui, ZHANG Gaoqiang, LI Wei, ZHAO Lin
2015, (5): 78-83. doi: 10.3963/j.issn 1674-4861.2015.05.012
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In order to optimize the locations of emergency resource stations for flood prevention along highway net-work,a multi-objective optimization layout model is developed in the study with a focus on the arrival time of resources, construction cost of stations and functions of highways.A particle swarm optimization (PSO)algorithm is used to opti-mize the model.The optimizing layout method for emergency resource stations for flood prevention along highway net-work is proposed.The results of applying the optimization model to highway network in Beijing indicate that the solutions from the PSO algorithm are practical and meet the requirements of emergency responses.
An Improved Method of Extracting OD Information Based on Mobile Phone Data
HU Yongkai, SONG Lu, ZHANG Jian, RAN Bin
2015, (5): 84-90,111. doi: 10.3963/j.issn 1674-4861.2015.05.013
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Mobile phone network data has been wildly used in origin-destination (OD)survey.To extract OD data from cellular data,there are two key steps:identifying travel endpoints;and matching them with traffic analysis zones (TAZs).The assumptions about cellular signal coverage in existing studies are quite different from the reality,which leads to complex analysis processes with low accuracy.Two improved methods were proposed to address such issues, based on the analyses about the features and application conditions of traditional TAZ and cell clustered TAZ.For tradi-tional TAZ,the matching accuracy of travel endpoint location is increased by identifying the maximum coverage areas of base stations,and by excluding those areas that are inaccessible using the maximum travel distances.This method is found to be effective for improving the matching accuracy of a portion of travel origin/destination points.For cell clustered TAZ,the cluster process is improved by removing less important steps.Then it is found that the method becomes simp-ler,but the matching accuracy remains to be very similar.
A Simulation of Vehicle Emissions in Beijing Using Gauss Gas-diffusion Model
ZHANG Chen, LI Ru, LUO Liuhong
2015, (5): 91-97,116. doi: 10.3963/j.issn 1674-4861.2015.05.014
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This paper develops a set of comprehensive factors for modeling vehicle emissions in Beijing,by using a calibrated of Mobile6.2 model in conjunction with the observed traffic volumes,the vehicle registration data from the Chi-na Statistical Yearbooks,the consumption of gas fuel and climate data of Beijing.Based on a Gauss diffusion formulation and a Matlab program,this paper develops presents the relationship between spatial distribution of vehicles and emission concentration under different conditions.The concentration maps show that the exhaust pollution is concentrated in the range of the area within 1.5 km around the ring roads;the average emission concentration is 100 times higher than the limits from the Air Quality Standard Grade 2 when taking SO 2 as an example.A comparison between the results from the model and the observed data is conducted and it is found that the relative deviation is less than 20%.
An Analysis of the Effects of Congestion Pricing Using a System Dynamics Approach
LIAO Lueling, PENG Hongqin, SONG Zihang
2015, (5): 98-104. doi: 10.3963/j.issn 1674-4861.2015.05.015
Abstract(179) PDF(1)
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In order to accurately describe the operation states of urban transport systems,the relationships between various elements of urban transport systems are analyzed.The reasons leading to traffic congestion and the impact of con-gestion pricing are thoroughly described.Considering the interactions between economy,population and environment in conjunction with the impact of the policy of car purchasing restriction,a system dynamics model is developed and used to study the effects of congestion pricing.Effects of the congestion pricing are investigated in the following two aspects:traf-fic and environment impact with a focus on traffic performance index,average speed,and NO x emissions.The predicted results of traffic conditions and environment impact in Beijing between 201 5~2020 show that it would have the best effect when the congestion pricing is 1 6 Yuan per vehicle with a main target of alleviating traffic congestion;higher than 1 6 Yuan per vehicle will result in the waste of road resources.Otherwise,if taking both traffic and environment impact into consideration,when congestion pricing is set to 1 1 Yuan per vehicle,which is slightly lower than the average value of travel time,it cannot only alleviate traffic congestion,but also reduce emissions.
An Analysis of Land Development at Intercity Railway Stations:A Case Study of Guangzhou-Qingyuan Intercity Railway
MENG Xinxin
2015, (5): 105-111. doi: 10.3963/j.issn 1674-4861.2015.05.016
Abstract(186) PDF(0)
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With the rapid development of urban agglomeration,intercity railways not only strengthen the connection between the city groups,but also accelerate the development of the areas along the line.Intercity railways have significant impacts on the infrastructure of surrounding areas.Therefore,the scale of land development needs to be precisely con-trolled and land use needs to be well planned before construction.A prediction model of intercity railway passengers is op-timized in this paper by analyzing the relationship between intercity railways and land uses.Assuming that the land develop-ment area is a constant,the peak-hour passenger flows at any given station can be calculated.The results of the model,in addi-tion to indicators such as land development intensity,passenger flow rate and population,are used to forecast the passenger flows attracted to the stations.Taking these indicators into consideration,a predication model of daily passenger flows is proposed based on land uses.The average daily passenger flows can be predicted through traffic forecasting,and thus a more effectively control of the scale of land development can be achieved.In this paper,the Guangzhou-Qingyuan Intercity Railway Stations are used for a case study.The results confirmed the accuracy,feasibility and efficiency of the model.
A Simulation Study of Temperature Field of Ceramic Asphalt Pavement
DING Jing, DING Jianming, LUO Sang
2015, (5): 112-116. doi: 10.3963/j.issn 1674-4861.2015.05.017
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Ceramic asphalt concrete is produced by replacing fine aggregate of SMA-13 with different amount of ce-ramic powder.The percentages of replacement by volumes are 10%,20%,30%,40% or 50%.The thermophysical pa-rameters of ceramic asphalt concrete are studied.A model of pavement temperature field is developed based on the heat conduct theory to simulate the temperature variation during the operations and the heat loss during the constructions for the ceramic asphalt concrete with different amounts of ceramic replacement.A rutting model of pavement is also devel-oped in this study to simulate the permanent deformation under the coupling effects of temperatures and loadings.The re-sults show that the heat conductivity coefficient for the concrete with ceramic decreases.When the ceramic replacement reaches 50%,the highest temperature at 4 cm below the ceramic asphalt concrete surface during the operations decreases by 4.42 ℃;the effective compacting time increases 24 min during the constructions;and the permanent deformation is 1. 12 cm,which decreases by 56% comparing to SMA-13 asphalt concrete.
2015, (5): 117-117. doi: 10.3963/j.issn.1674-4861.2015.05.020
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2015, (5): 118-118. doi: 10.3963/j.issn.1674-4861.2015.05.021
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