2016 No. 3

Display Method:
2016, 34(3): . doi: 10.3963/j.issn.1674-4861.2016.03.001
Abstract(111) PDF(1)
Abstract:
An Analysis on the Impact of Highway Factors on Severity of Typical Traffic Crashes
WANG Changjun, WANG Liyang, LI Ruimin
2016, 34(3): 10-17. doi: 10.3963/j.issn1674-4861.2016.03.002
Abstract(153) PDF(3)
Abstract:
With the purpose to improve the road traffic safety,it is important to investigate the factors which have impacts on the severity of traffic crashes.Based on the data of traffic crashes in recently years which include serious colli-sions,the types of crashes are distinguished using Poisson Model and Negative-binomial Model.These models are also used for establishing an estimation model of fatality rate for three typical crash types:rear-end crashes,lateral impact crashes and pedestrian-involved crashes.In this model,the fatality is a dependent variable and highway factors are inde-pendent variables,the numbers of persons involved in each crash is a modified variable.The parameters of this model are determined by the over-dispersion parameter and Akaike Information Criterion (AIC)method.The results indicate that the grade of highway and roadside protective facilities significantly correlate with the fatality of rear-end crashes.Weather, conditions of road surface,locations of segments or intersections,gradient of roads,and structure of pavement are all rel-evant with lateral impact crashes.The factors of conditions of road surface,grade of roads,numbers of lanes,and radius of curve are relevant with pedestrian-involved crashes.This innovated method on severity of traffic crashes proposed in this study can be further used for analyses on extremely serious traffic crashes.This study could be used as a reference for accident analysis and design of roads as well.
Roadside Safety Assessment Based on Set Pair Analysis
WANG Jian, YAN Lijing
2016, 34(3): 18-26. doi: 10.3963/j.issn1674-4861.2016.03.003
Abstract(98) PDF(2)
Abstract:
In order to improve the roadside safety of low-grade highways in mountain areas,a set pair analysis based on projection pursuit model is proposed.This method using the projection pursuit technology that can objectively deter-mine the index weighs of sample data from candidate roads,which avoids the subjectivity and limitation of experts.Tak-ing the features of evaluation indices into account,the definitive information coexists with dubious information.The set pair analysis theory is applied to establish an evaluation matrix on degrees of connection,which describes the relationship between evaluation indices and risk ranks from three aspects:identity,difference,and antagonism.In order to verify this model,the low-grade roads in the City of Chengde,China are selected as a case study .Compared to the method based on the grey cluster theory which considers data as value,this proposed model takes data as an information carrier,which contains more information and can make evaluation results more reliable.When evaluating the third segment in the case study,the evaluation result of gray clustering is [0.0332 0.1741 0.4171 0.3948],which shows its limitation when regard-ing samples as data,makes it difficult to determine the safety level between III and IV.By contrast,the evaluation result of proposed model is [0.1800 0.9701 2.382 0.2398],which clearly determine the safety level of the road as III.The results show that roadside safety assessment based on set pair analysis is more feasible and reasonable.
An Analysis on Effective Factors of Safety for Urban Expressways Based on Bayesian Spatial Models
YIN Juyuan, LI Tienan, SUN Jian
2016, 34(3): 27-33,40. doi: 10.3963/j.issn1674-4861.2016.03.004
Abstract(129) PDF(3)
Abstract:
Expressways are the backbones of the urban traffic network.The safety situation on expressways can di-rectly affect the efficiency of traffic.50 069 accidents occurred in the year 2011-2013 is collected by central video monitor system in a three-year period.Based on traffic flow data from dual-loop detectors and accidents data,a Bayesian spatial model is developed to analyze four expressways in the City of Shanghai:North-South elevated road,Yan′an elevated road,Inner Ring,and Middle Ring.In order to reveal the potential spatial correlation among road segments,an adjacent-correlation spatial model is developed by adding a spatial random-effect factor to the negative binomial model.Further,a spatial correlation model of distance is developed by improving the proximity matrix of the factor.The Bayesian method is applied to estimate the parameters and compare the regression results of these three models.The results show that the spatial correlation model of distance is superior in terms of goodness-of-fit.The deviance information criterion (DIC)of the spatial correlation model of distance is 6.04% lower than which in the negative binomial model.It indicates that the distribution of accidents on expressway segments is spatial correlated and is related to the distance between segments.An analysis on road geometric features shows that the risk of accident tends to be higher with a larger number of ramps with-in 1 km before or after the midpoint of segments;the cumulative turning angle per kilometer is larger as well.Weaving segments between on-ramps and off-ramps have a higher risk of accident.The volume of average daily traffic shows a sig-nificant positive correlation with accidents.Compared with the other two expressways,the risk of accident on Inner Ring is higher;while Middle Ring is relatively lower.
An Evaluation of Management Level of Traffic Safety in Road Passenger Transportation Enterprises Based on Combination Weighting Method
LU Guangquan, LUO Yi, CAI Fengtian
2016, 34(3): 34-40. doi: 10.3963/j.issn1674-4861.2016.03.005
Abstract(166) PDF(1)
Abstract:
Qualitative evaluations on the safety of road passengers have been widely accepted by most transportation enterprises in China.Current studies are thus motivated,and a survey of 16 road passenger transportation enterprises is conducted to obtain relevant data.An evaluation system of traffic safety is established,which includes three major indi-ces:enterprise system,drivers,and vehicles.A combination weighting method of analytic hierarchy process (APH)and an entropy method is applied for determining the weight of these indices.Statistical data of the management level of traffic safety in enterprises are therefore used for correlation analysis.The results show that the Pearson correlation coefficient of this combination weighting method reaches -0.841,better than -0.793 in AHP,and -0.754 in entropy method.More-over,the ranking order of enterprises is generally consistent with the safety statistical data,which indicates that this combination weighting method can objectively reflect the actual management level of traffic safety in road passenger trans-portation enterprises.
A Conflict Model Involving Right-turning Vehicles and Cross-walking Pedestrians at Signalized Intersections
BAO Yiting, ZHOU Zhuping, XU Yongneng
2016, 34(3): 41-49. doi: 10.3963/j.issn1674-4861.2016.03.006
Abstract(147) PDF(5)
Abstract:
Normally,the right-turning movement of vehicles at signalized intersections is not controlled.Thus, there are potential risks of conflicts between the right-turning vehicles and cross-walking pedestrians.Current studies ad-dressed on the identification and classification of such conflicts,no theoretical model is proposed to analyze such processes of conflicts.With the purpose to reduce conflicts and improve safety of pedestrians,a new simulation model to describe the conflict processes between right-turning vehicles and cross-walking pedestrians is proposed in this study.The decision-making process of right-turning vehicles is studied.Then the mechanism of conflicts between vehicles and pedestrians is analyzed.Finally,a vehicle-pedestrian conflict model is established.Meanwhile,the coefficients for this model are calibra-ted using actual data including vehicle speed and gap acceptance.A simulation study is then conducted to optimize the measurements for safety evaluation:time-to-collision (TTC),post-encroachment time (PET),safety braking decelera-tion,and gap time.The results reveal that PET is the most significant measurement to evaluate vehicle-pedestrian con-flict.The accuracy analysis results show that the deviation of vehicle speed and PET between simulation and actual data is less than 5%,which indicates the validity of this model.An implementation of sensitivity analysis shows that PET of small size intersections increases 10% compared with large size of intersections,which indicates that small intersections have the advantage to reduce the severity of conflicts.
A Computation Method of Parking Allocation for Super High-rise Buildings:A Case Study of Xi′an
ZHU Zhenjun, ZENG Jun, ZHANG Shengrui, CHEN Hongsheng
2016, 34(3): 50-56. doi: 10.3963/j.issn1674-4861.2016.03.007
Abstract(116) PDF(1)
Abstract:
Appropriate parking allocation for super high-rise buildings is important for solving parking problems in big cities.In this paper,core-affected areas of super high-rise buildings is proposed based on the service ability of public transportation.Then summarize the demand characteristics of super high-rise buildings that have been built in China.The equilibrium theory is used to take overall consideration of internal and external environment of super high-rise buildings. The accessibility and service ability of public transportation which belongs to external environment,and the built-up areas and utility index of shared-parking of super high-rise buildings which belongs to internal environment,are selected as main influence factors.According to the standards of these main factors,a reduction coefficient of parking allocation for super high-rise building is studied.Then a computation method is proposed to gradually reducing the standard of parking allocation for ordinary building in urban areas.Taking service ability of public transportation into consideration,the ra-tionality of allocation reduction is validated within the core-affected areas.A super high-rise construction project in Xi′an is taken as a case study.The results show that every 100 m2 should allocate for 0.45 parking spaces,which is significantly less than which in specific standards.Rationality of computation results are validated form the aspects of limited parking resources in central urban areas,administrative regulation for parking and comparative analysis of parking allocation for major cities in China.
A Computation Method of Evaporation and Holding Time of LNG Tank with Marine Fuel
TIAN Zhugang, YIN Qizhi, WANG Bing
2016, 34(3): 57-63. doi: 10.3963/j.issn1674-4861.2016.03.008
Abstract(682) PDF(24)
Abstract:
Computation of evaporation and holding time of Liquefied Natural Gas (LNG)tank with marine fuel is important in the design of boil-off gas treatment system for the LNG powered ships.A computation method for the evapo-ration and holding time of LNG tank with marine fuel is presented.The evaporation rate of liquid nitrogen and LNG is an-alyzed respectively by using the heat transfer formula.The relationship between static evaporation rate of liquid nitrogen and LNG is derived.For the situations of small pressure variations,the computation formula of LNG evaporation rate is obtained by the relationship of density of LNG and its latent heat of vaporization under different pressures.The computa-tion formula of LNG evaporation is therefore deduced from the average evaporation rate of LNG.The holding time of LNG tank is computed according to the change of gas weight in the storage tank.As a case study,the evaporation and holding time of a 20 m3 LNG tank are computed by two different methods.The evaporation computed with average evapo-ration rate of LNG is 20.72 kg.It is 34.1 kg in computation with evaporation rate of liquid nitrogen.The holding time computed by the former method is 21.64 d;and 13.15 d of the later method.The evaporation computed with average e-vaporation rate of LNG is 13.38 kg less,and the holding time is 8.49 d shorter.The temporal variations of the evaporation computed by these two methods are generally consistent,while the evaporation and the holding time show great differ-ences.Comparing with the method based on the evaporation rate of liquid nitrogen,this method using average evaporation rate of LNG,provides solutions more consistent with the observations.This method can be further applied to guide the design of boil-off gas treatment system for the LNG powered ships.
A Short-term Forecasting of Traffic Flow Parameters Based on Decision Tree Theory
XUE Hongjun, CHEN Guangjiao, LI Xinmin, GU Li
2016, 34(3): 64-71. doi: 10.3963/j.issn1674-4861.2016.03.009
Abstract(243) PDF(4)
Abstract:
Due to the non-linearity feature of data series of traffic flow,a nonparametric predicting method based on the theory of decision tree is proposed to overcome the deficiencies of current short-term forecasting methods of traffic flow.Using time series lags,the data series of traffic flow are converted into a format which can be recognized by a non-parameter model.Considering the long-term co-integration relationship between traffic flow parameters,combinational vectors of volume and speed lags are established,providing a basis for this forecasting model.Then a decision tree model based on classification and regression tree (CART)is developed for the prediction for the parameters of short-term traffic flow.Based on actual data of traffic flow,the performance of this CART decision tree model is evaluated under different types of road and speed intervals.The results show that the CART decision tree model is superior to the general time se-ries model in terms of the prediction accuracy.In addition,the accuracy of speed prediction is generally higher than that of volume prediction.The mean average percentage error (MAPE)of speed prediction is less than 13% while the MAPE of volume prediction is 30%.Besides,this model can perform better when it is constructed with the data from weekdays or weekends separately.The evaluation of performance under different speed intervals indicates that the CART decision tree model presents high accuracy and stability in medium intervals speed for all types of road.
Detection and an Analysis of Redundant RFID Traffic Data
YANG Yuesi, DU Wei, NING Dan, GUO Jianhua
2016, 34(3): 72-80. doi: 10.3963/j.issn1674-4861.2016.03.010
Abstract(121) PDF(3)
Abstract:
Data quality control is one of the key technologies for intelligent transportation systems.Radio Frequency Identification (RFID)data generally contain redundancy.According to the different characteristics,they can be broadly divided into two types:duplicate data and similar data.Redundancy detection is based on an analysis of the adjacent time for one vehicle.To identify the redundant RFID data,the curve of redundancy rate and time points of redundant data are extracted.Due to different characteristics of the redundancy types,their redundancy rates are computed separately.A de-tection algorithm is proposed,and applied to analyze the redundancy rate of RFID data in two aspects:RFID stations and shapes of redundancy curves.Moreover,a cleansing method for redundant data is also proposed.As a case study,raw RFID data are collected from 21 RFID stations on the main road in the City of Nanjing.The results show that the average rate of duplicate data is 0.006 2%;which of similar data is 0.92%.Moreover,in each RFID station,the amount of similar data is much larger than that of duplicate data.From the shape-of-redundancy-curve point of view,it is observed that the leveling off or tail rising curves are related to the stations with high redundancy rates;while the straight up curves imply low redundancy rates.Based on the analysis,several measures are proposed to control redundant RFID data.
Detection of Vehicle Queuing at Toll Stations on Highways Based on Departure Time
JIN Yinli, SHI Shaogang, WANG Jun
2016, 34(3): 81-87. doi: 10.3963/j.issn1674-4861.2016.03.011
Abstract(121) PDF(1)
Abstract:
The data for performance evaluation of toll station services on highways is largely collected by people or by professional detection equipment,which has disadvantages in staff and financial costs.The big data from toll stations on highways is much easier to collect,which has great potentials in applications to evaluate service performance of toll stations.The analyses on limitations and deficiencies of the latest studies on vehicle queuing at toll stations on highways are carried out at first.Based on the data from toll stations on highways,the statistical regularities of the departure time between consecutive vehicles in the same lane are further studied during the queuing situations.Systematic solutions are proposed,including a detection algorithm of vehicle queuing at toll stations,and an algorithm of quantitative measure-ment on queue length,waiting time,and service time.Three case studies are carried out by using the data from Fuping, Hancheng and Zhichuan toll stations in Shaanxi Province,respectively.The results from these proposed algorithms are compared with actual situations as well as with the results of the M/G/1 model.The results indicate that the absolute er-ror of average service time is within 3 s.The absolute error of average queue length is within 1 vehicle,except the 105 lane of Hancheng toll station.The absolute error of average waiting time is within 10 s,except the 101 lane of Fuping toll station.According to the above findings,it can be concluded that these proposed algorithms are suitable for evaluating service performance of highway stations.The results also indicate that the proposed algorithms are flexible to deal with different types of highway toll stations.
The Critical Length of Slopes on Highways for Heavy-duty Vehicles
XU Ting, LI Min, YANG Xinxin, SHI Yongquan, MA Zhuanglin, YAN Ying
2016, 34(3): 88-95. doi: 10.3963/j.issn1674-4861.2016.03.012
Abstract(154) PDF(1)
Abstract:
The unreasonable combination of length and grades of slopes leads to undesirable reduction of heavy-duty vehicles′speeds in mountain areas.Even worse,it would result in serious traffic accidents.Based on force conditions and operational characteristics in climbing processes,a kinetic model is developed with a case study of a heavy-duty vehicle. With the restriction of climbing abilities,the characteristics of climbing and regulations of speed reduction of a fully load-ed heavy-duty vehicle are simulated.With a certain power-to-weight ratio,the profiles of this vehicle′s climbing speed are explored,using slope gradients and approaching speeds as two controls respectively.The attenuation curve of speeds shows that the approaching speed is positively related to the critical length of slopes,but has no influence on the steady climbing speed.For this heavy-duty vehicle with a low climbing performance,when the approaching speed is 80 km/h, the critical length is restricted to 400 m;while the speed is 60 km/h,the critical length is restricted less than 300 m, which are less than the corresponding value in current national standard Technical Standard of Highway Engineering . Therefore,when the speed reduction exceeds 20 km/h in climbing processes,it is necessary to set climbing lanes or rele-vant facilities,which is also given according to the simulation result.
The Variation ofα Rhythm of EEG of OSAHS Drivers in Driving Simulation
WU huili, WEI xinfa, CHEN Gang, YAN yang
2016, 34(3): 96-100,107. doi: 10.3963/j.issn1674-4861.2016.03.013
Abstract(130) PDF(1)
Abstract:
The main symptom of drivers with obstructive sleep apnea hyperpnoea syndrome (OSAHS)commonly have excessive daytime sleepiness,which would increase the probability of mis-operations that may result in accidents.As a result,it is crucial to identify the physiological status of OSAHS drivers in order to avoid or reduce the probability of accidents.The brain waves,which can reflect the physiological changes of OSAHS drivers,are used to identify the driv-ing state in this paper.The indicators for early warning of accidents are identified.20 drivers with OSAHS are recruited to drive in a driving simulator while detecting their brain waves.The driving environment and requirements,such as prohibi-tions of phone calls and over speed,etc.,are identical for all of the drivers.The values ofα andβ rhythm of EEG as well as accident types and occurrence times are recorded during the simulations.The fluctuations of brain waves under different driving conditions are analyzed from both macro (waveforms)and micro (data)perspectives.The results indicate that theα rhythm is either suppressed or vanished when an accident occurs.The mean value ofβ/(α+β)during an accident has significant distinctions with which in regular driving modes.As a result,both the change ofα rhythm and the average val-ue ofβ/(α+β)can be recognized as early warning indicators of sleepiness for OSAHS drivers during driving.Further-more,the average value ofβ/(α+β)in 30 s before the accidents can be treated as a threshold value of early warning of accidents.
Routing Optimization of Multiple Rubber-tired Gantry Cranes Considering Carbon Emission
HUANG Xiaobo, ZHU Ning, ZHU Jianhua, LI Geng
2016, 34(3): 101-107. doi: 10.3963/j.issn1674-4861.2016.03.014
Abstract(152) PDF(3)
Abstract:
Rubber-tired gantry cranes (RTGs)are important resources in container terminals.It is essential to schedule multiple RTGs effectively so as to reduce both carbon emissions and operating costs.Based on the feature of RTGs that they cannot cross each other,and other constrains,three sources of carbon emission during moving process, loading and unloading process,and preparing process are taken into consideration.A mathematical model of route pro-gramming for RTGs is developed to minimize the carbon emissions.For the computational complexity of a mixed integer programming model,a path strategy for RTGs is designed.A simulated annealing algorithm is applied to find the near-optimal solution.Numerical experiments are performed to evaluate the effects of new methods in three aspects:route lengths,total carbon emissions,and operational efficiency.Compared with the shortest path optimization method,this new model can increase the route lengths by 8.82%,while the runtime only increases by 0.21 s.The carbon emission re-duces by 3.3%.This method can guarantee working efficiency of RTGs,and effectively solve the problem of RTGs rou-ting with low-carbon emission.Compared with the genetic algorithm and the ant colony optimization,the accuracy of this proposed algorithm can improve the accuracy by 1.13% and 2.24%,respectively.In addition,the operational efficiency increases by 9.82% and 5.92%,respectively.
An Analysis of Influencing Factors of Workload of Air Traffic Controllers Based on Weighted Gray Correlation Degree
GAO Wei, GAO Xing
2016, 34(3): 108-115,125. doi: 10.3963/j.issn1674-4861.2016.03.015
Abstract(114) PDF(1)
Abstract:
In order to precisely evaluate the workload of air traffic controllers,quantitative analyses of effective fac-tors are significant.Considering the traffic situation in sectors as well as the performances of controllers,14 key factors are identified in the analysis of controllers′ workload,the weights of which are computed by grey correlation entropy. Then an analysis on the workload of air traffic controllers is conducted,and the magnitude of its identification coefficient is optimized.The data collected from a radar simulator of 01/19 area in a control sector of Beijing are applied for model validation.It indicates that the number of ground-air communication,times of equipment operation,and sector access in-dex are the most important factors influencing the workload of controllers.The weighted gray correlation degree of these three factors are 0.844 0,0.796 1,and 0.693 5 respectively.Moreover,the ranking results of weighted gray correlation degree are consistent with the controllers′subjective ranking results by Analytic Hierarchy Process (AHP)method.The relative importance of influencing factors on air traffic controllers′workload can be revealed by the weighted gray correla-tion degree analysis.
An Effectiveness Evaluation of Waterway Transportation Emergency Response Performance Based on a Workflow Model
GUI Heng, WANG Tengfei, WANG Yang, WU Qing
2016, 34(3): 116-125. doi: 10.3963/j.issn1674-4861.2016.03.016
Abstract(139) PDF(1)
Abstract:
Intensive information transmission and exchange during emergency response is significant for its perform-ance.However,quantitative modeling and performance improvement on the timeliness and efficiency of rescue operations and decision instruction flow are absent in existing studies on mechanism of emergency response in waterway transporta-tion.A workflow model is introduced into the timeliness and accuracy assessment of information flow in waterway emer-gency response.Based on the analysis on the procedure of waterway emergency response and several typical waterway ac-cident scenarios,an instruction repository is added onto the organization time resources messages net (OTRM-NET) workflow model.On the basis of the conventional Petri-net model,a waterway emergency response model contains deci-sion information feedback is proposed.Moreover,the estimated period of operation can be computed by time performance of this model.Simulations are utilized to compare the operation time of OTRM-NET with that of conventional scheme. The efficiency of information transmission is quantitatively represented by error transmission rate and an algorithm on performance of information delivery is furthermore proposed.This algorithm is simulated in emergency response plans to compute the efficiency of information delivery.This model is applied to a case study of a specific waterway accident.When comparing the emergency time of OTRM-NET with that of other models,the values are reduced by 2 721 s on average. Taking the information delivery library of the ships involve in a typical accident as a case study,the overall transmissibili-ty of the accident identified by vessel traffic system (VTS)is decreased from 15% to 9.52%.The local transmissibility of the accident found by VTS is declined from 37.5% to 22.22%.Those indicate that by adding confirmation of ship informa-tion,the influence of false alarm from VTS is decreased by 36.53%.And the impacts on transmission of accident infor-mation are decreased by 40.75%.Meanwhile,the execution deviation can be detected and corrected ahead of 2 duty cy-cles,which would reduce the instruction deviation within the workflow.This proposed efficiency evaluation model is prac-tical in supporting emergency planning and formulation of the workflow of emergency response in multi-task and multi-role environment.
A Regional OD Matrix Estimation Method Based on Select Link Analysis
LIU Xinjie
2016, 34(3): 126-133. doi: 10.3963/j.issn1674-4861.2016.03.017
Abstract(160) PDF(4)
Abstract:
It is difficult to carry out a wide range of origin-destination (OD)surveys for vehicles.The regional OD matrix is commonly estimated by traffic flow in road sections.Considering the fact that the distribution structure cannot be verified through traditional OD estimation methods,a new method is proposed.This method updates the regional OD matrices with a Select Link analysis and replaces them with “real”OD matrices.Firstly,a specific sectional OD matrix computed by Select Link is subtracted from the regional priori OD matrix;then a “real”matrix of this road section is used to update the distribution of regional traffic flow.A two-step iterative replacement procedure is applied when there are multiple road sections in the regional priori OD matrix whose OD matrices need to be replaced by the “real”ones.The first step is to replace each sectional OD matrix one by one.One replaced matrix will be used as input for the next link. The second step is to replace the whole regional priori OD matrix based on the first step.A case study of Guilin Ring (East)highway has been conducted to verify this method.Compared with the traditional OD estimation methods,this new method resulted in an increase of 7% of the long-distance travels,which can reflect the variation of regional distribu tion of vehicles .The correlation coefficient between the assigned and the surveyed traffic flow of road sections reaches 0.99,which verifies the accuracy of the updated regional OD matrix.
2016, 34(3): 134-134. doi: 10.3963/j.issn.1674-4861.2016.03.019
Abstract(104) PDF(1)
Abstract:
Overview
An Overview of Studies and Applications on Traffic Performance Index
WANG Luyuan, YU Lei, SUN Jianping, SONG Guohua
2016, 34(3): 1-9,26. doi: 10.3963/j.issn1674-4861.2016.03.001
Abstract(324) PDF(15)
Abstract:
In order to quantitatively analyze the characteristics of traffic congestions,different models of traffic per-formance index (TPI)have been developed and applied in several cities.This study first analyzes the mechanisms,charac-teristics,and basic parameters in current models of TPI.Then,divide these models into two categories:macroscopic static models based on statistics,and dynamic models based on real-time data.The dynamic models are further divided in-to two sub-categories:models based on mileage fraction of severe congestions,and models based on travel-time ratio.By estimating TPI,this study comparatively analyzes the consistency,differences,and the sensitivity of these two sub-cate-gories of dynamic models based on the floating car data collected in the City of Beijing.