The acceptance gap micro control system applies to the entrance ramp in which the prior consideration is given to the merging safety. Based on the actual condition of interchanges and the vehicle composition in our c...The acceptance gap micro control system applies to the entrance ramp in which the prior consideration is given to the merging safety. Based on the actual condition of interchanges and the vehicle composition in our country, the traffic characteristics for high class roadways are analyzed and the system simulation model is developed. A simulation example is also given in the paper. Through the simulation, the optimal ramp control plan can be obtained.展开更多
The concept of control system of acceptable gap in the entrance ramp, the construction of the minimum acceptable gap and the method of determining it are introduced. On the above-mentioned basis and by taking the Chin...The concept of control system of acceptable gap in the entrance ramp, the construction of the minimum acceptable gap and the method of determining it are introduced. On the above-mentioned basis and by taking the Chinas reality into consideration, the issues on the design of control system of acceptable gap are approached in this paper.展开更多
To establish the empirical capacity model of an on- ramp merging section, the Erlang distribution is first selected to define the time headway distribution, and then the gap acceptance theory is applied to develop the...To establish the empirical capacity model of an on- ramp merging section, the Erlang distribution is first selected to define the time headway distribution, and then the gap acceptance theory is applied to develop the basic capacity model of the on-ramp merging section. Since not all the time headways on the shoulder lane can be made full use of by on- ramp vehicles, a modified capacity model is developed, which takes the usage probability of time headway into consideration. Then, a model of capacity discount coefficient ~： is developed. Finally, based on the modified capacity model and the model of capacity discount coefficient, an empirical merge capacity model which contains the shoulder lane volume, critical gap, and the distance from nose to merging point, is constructed. Results show that, compared with other models, the proposed model is more reasonable since it takes merging section geometry into consideration, and it is easy to apply. The merge capacity varies with the shoulder lane volume, the critical gap, the distance between the nose and the merging point, and the design velocity of the shoulder lane and ramp.展开更多
Based on the gap acceptance theory, the mixed traffic flow composed of r representative types of vehicles 1, 2,…, r vehicles is analyzed with probability theory. Capacity model of the minor mixed traffic flow ...Based on the gap acceptance theory, the mixed traffic flow composed of r representative types of vehicles 1, 2,…, r vehicles is analyzed with probability theory. Capacity model of the minor mixed traffic flow crossing m major lanes with M3 distributed headway on the unsignalized intersection is set up, and it is an extension of capacity model for one minor lane vehicle type crossing one major lane traffic flow.展开更多
Highway capacity is defined as maximum volume of traffic flow through the particular highway section under given traffic conditions, road conditions and so on. Highway construction and management is judged by capacity...Highway capacity is defined as maximum volume of traffic flow through the particular highway section under given traffic conditions, road conditions and so on. Highway construction and management is judged by capacity standard. The reasonable scale and time of highway construction, rational network structure and optimal management mode of highway network can be determined by analyzing the fitness between capacity and traffic volume. All over the world, highway capacity is studied to different extent in different country. Based on the gap acceptance theory, the mixed traffic flow composed of two representative vehicle types heavy and light vehicles is analyzed with probability theory. Capacity model of the minor mixed traffic flows crossing m major lanes, on which the traffic flows fix in with M3 distributed headway, on the unsignalized intersection is set up, and it is an extension of minor lane capacity theory for one vehicle-type and one major-lane traffic flow.展开更多
To determinate the combined effect of bus bay stops near access points on the expressway capacity,a new theoretical approach is developed on the basis of gap acceptance theory and queuing theory. According to the loca...To determinate the combined effect of bus bay stops near access points on the expressway capacity,a new theoretical approach is developed on the basis of gap acceptance theory and queuing theory. According to the location between the bus stop and the access upstream or downstream,the capacity models on the expressway are developed for four cases. The results show that there are no significant differences in the capacity among four cases when the bus arrival rate is less than 60 veh / h and the car volume at the entrance and exit is less than 200 pcu / h. As the bus arrival rate and the car volume at the entrance and exit increase,the bus stops at downstream of an entrance and upstream of an exit have remarkable effect on the capacity. The increasing of berth number of the bus stop has a positive effect on the capacities of four cases.展开更多
In order to describe the time-headway distribution more precisely in urban traffic network,the mixed distribution model was introduced which has been widely used in mathematical statistics,and a capacity model of unsi...In order to describe the time-headway distribution more precisely in urban traffic network,the mixed distribution model was introduced which has been widely used in mathematical statistics,and a capacity model of unsignalized intersections was obtained based on gap acceptance theory.The new model is suitable for absolute and limited priority controlled conditions and can be regarded as a more general form which handles simple headway distributions including lognormal distribution,negative exponential distribution and shifted negative exponential distribution.Through analyses of the main influencing factors in this model,the proportion of free flowing and the standard variance of gaps between any two continuous following vehicles are high sensitivity with the capacity when major stream volume is low.Besides,the capacity is affected deeply by the mean value of following vehicle gaps when major stream value is fixed and the proportion of free flowing is small.At last,the observed minor stream capacity is obtained by the survey date in Changchun city,and the average relative error between the theoretical capacity proposed in this paper is 13.73%,meanwhile the accuracy increases by 16.68% compared with the theoretical value when major stream obeys shifted negative exponential distribution.展开更多
Delay is one of the most crucial factors for both pedestrians and car drivers around pedestrian crossings.Drivers often do not yield to pedestrians,which may result in both delay and impatient pedestrian behaviour.Thi...Delay is one of the most crucial factors for both pedestrians and car drivers around pedestrian crossings.Drivers often do not yield to pedestrians,which may result in both delay and impatient pedestrian behaviour.This tendency may alter after introducing autonomous vehicles as the vehicles will follow the traffic rules in all cases.This study aims to estimate the delay time alteration at a simple zebra crossing using on-site measures and simulation.Roadside video recordings were carried out in Budapest,Hungary,to obtain the crossing decisions of pedestrian groups based on the approaching vehicle distance.We have determined the accepted vehicle distance vales for pedestrian groups that served as input data for microsimulation modelling.The novelty of the study is that the simulation involved autonomous vehicles that hold preset headways from the leading vehicle.The simulation was designed based on the traffic share of autonomous vehicles and the headways they kept.The main findings are that the travel time and stopping time for cars are higher if the modal share of autonomous vehicles is high.For pedestrians,however,we found a slight decrease in both travel times and stopping times.Moreover,we have proposed modifications to the simulation software(Vissim)to handle distancedependent pedestrian decisions and drivers'failure to give priority.The results can be useful for road operators to estimate the road capacity in the era of autonomous vehicles and for software developers to formulate the simulated and real driving mechanism for autonomous vehicles.展开更多
The lane changing decision model(LCDM)is a critical component in semi-and fully-automated driving systems.Recent research has found that the fuzzy inference system(FIS)is a promising approach to implementing LCDMs.To ...The lane changing decision model(LCDM)is a critical component in semi-and fully-automated driving systems.Recent research has found that the fuzzy inference system(FIS)is a promising approach to implementing LCDMs.To improve the FIS’s performance,this research reviewed the challenges in the development an FIS model to make the yes;nof g decisions in discretionary lane changes.The FIS model was revised to bring its fuzzy inference rules more consistent with the fuzzy membership functions,and its com-position and defuzzification methods more in line with the classical fuzzy logic theory.An equitable test data set with approximately equal number of yes;nof g data points was assembled from the same next generation simulation(NGSIM)data used in the past research.The test results proved that:(1)an LCDM’s performance was dependent on how the yes;nof g decisions in the test data set were manually labeled;(2)separating the fuzzy inference rules into a yesf g group and a nof g group and compute the results sep-arately yielded potentially better decision accuracy.Furthermore,The gene expression pro-gramming model(GEPM)performed better than the improved FIS-based model.The findings led the authors to suggest two possible research directions:(1)add the subject vehicle’s speed as an input to the LCDM and redesign the decision-making model;(2)con-struct models for congested and uncongested traffic separately.The authors further sug-gested the use of instrumented vehicles to collect a set of high-fidelity lane changing data in the naturalistic driving environment.展开更多
Pedestrians usually cross the road at mid-block locations in India because of the ease and convenience to reach their destination as compared to intersection locations. It is important to evaluate the pedestrian gap a...Pedestrians usually cross the road at mid-block locations in India because of the ease and convenience to reach their destination as compared to intersection locations. It is important to evaluate the pedestrian gap acceptance behavior at mid-block locations because of inadequate vehicular gaps un- der mixed traffic condition, which translates into the pedestrian road crossing behavior. The present study examines the pedestrian gap acceptance behaviour by employing an artificial neural network （ANN） model for understanding the decision making process of pedestrians, i. e. , acceptance or rejec- tion of vehicular gaps at a mid-block location. From the results it has been found that the pedestrian rolling gap, frequency of attempt, vehicular gap size, pedestrian speed change condition and vehicle speed have major role in pedestrian gap acceptance. These results can lead to a better design of pedestrian crossing facilities where adequate gaps are not available in vehicular flow at mid-block crosswalk locations.展开更多
文摘The acceptance gap micro control system applies to the entrance ramp in which the prior consideration is given to the merging safety. Based on the actual condition of interchanges and the vehicle composition in our country, the traffic characteristics for high class roadways are analyzed and the system simulation model is developed. A simulation example is also given in the paper. Through the simulation, the optimal ramp control plan can be obtained.
文摘The concept of control system of acceptable gap in the entrance ramp, the construction of the minimum acceptable gap and the method of determining it are introduced. On the above-mentioned basis and by taking the Chinas reality into consideration, the issues on the design of control system of acceptable gap are approached in this paper.
基金The National Natural Science Foundation of China(No.51278520 51278220)the Science and Technology Development Project of Jilin Province(No.20130206093SF)
文摘To establish the empirical capacity model of an on- ramp merging section, the Erlang distribution is first selected to define the time headway distribution, and then the gap acceptance theory is applied to develop the basic capacity model of the on-ramp merging section. Since not all the time headways on the shoulder lane can be made full use of by on- ramp vehicles, a modified capacity model is developed, which takes the usage probability of time headway into consideration. Then, a model of capacity discount coefficient ~： is developed. Finally, based on the modified capacity model and the model of capacity discount coefficient, an empirical merge capacity model which contains the shoulder lane volume, critical gap, and the distance from nose to merging point, is constructed. Results show that, compared with other models, the proposed model is more reasonable since it takes merging section geometry into consideration, and it is easy to apply. The merge capacity varies with the shoulder lane volume, the critical gap, the distance between the nose and the merging point, and the design velocity of the shoulder lane and ramp.
文摘Based on the gap acceptance theory, the mixed traffic flow composed of r representative types of vehicles 1, 2,…, r vehicles is analyzed with probability theory. Capacity model of the minor mixed traffic flow crossing m major lanes with M3 distributed headway on the unsignalized intersection is set up, and it is an extension of capacity model for one minor lane vehicle type crossing one major lane traffic flow.
基金Supported by the National Natural Science Foundation of China（50478071）
文摘Highway capacity is defined as maximum volume of traffic flow through the particular highway section under given traffic conditions, road conditions and so on. Highway construction and management is judged by capacity standard. The reasonable scale and time of highway construction, rational network structure and optimal management mode of highway network can be determined by analyzing the fitness between capacity and traffic volume. All over the world, highway capacity is studied to different extent in different country. Based on the gap acceptance theory, the mixed traffic flow composed of two representative vehicle types heavy and light vehicles is analyzed with probability theory. Capacity model of the minor mixed traffic flows crossing m major lanes, on which the traffic flows fix in with M3 distributed headway, on the unsignalized intersection is set up, and it is an extension of minor lane capacity theory for one vehicle-type and one major-lane traffic flow.
基金National Basic Research Program of China(No.2012CB723303)
文摘To determinate the combined effect of bus bay stops near access points on the expressway capacity,a new theoretical approach is developed on the basis of gap acceptance theory and queuing theory. According to the location between the bus stop and the access upstream or downstream,the capacity models on the expressway are developed for four cases. The results show that there are no significant differences in the capacity among four cases when the bus arrival rate is less than 60 veh / h and the car volume at the entrance and exit is less than 200 pcu / h. As the bus arrival rate and the car volume at the entrance and exit increase,the bus stops at downstream of an entrance and upstream of an exit have remarkable effect on the capacity. The increasing of berth number of the bus stop has a positive effect on the capacities of four cases.
基金Sponsored by the National High Technology Research and Development Program of China(Grant No.2011AA110304)the National Natural Science Foundation of China(Grant No.50908100,70971053)
文摘In order to describe the time-headway distribution more precisely in urban traffic network,the mixed distribution model was introduced which has been widely used in mathematical statistics,and a capacity model of unsignalized intersections was obtained based on gap acceptance theory.The new model is suitable for absolute and limited priority controlled conditions and can be regarded as a more general form which handles simple headway distributions including lognormal distribution,negative exponential distribution and shifted negative exponential distribution.Through analyses of the main influencing factors in this model,the proportion of free flowing and the standard variance of gaps between any two continuous following vehicles are high sensitivity with the capacity when major stream volume is low.Besides,the capacity is affected deeply by the mean value of following vehicle gaps when major stream value is fixed and the proportion of free flowing is small.At last,the observed minor stream capacity is obtained by the survey date in Changchun city,and the average relative error between the theoretical capacity proposed in this paper is 13.73%,meanwhile the accuracy increases by 16.68% compared with the theoretical value when major stream obeys shifted negative exponential distribution.
基金the Hungarian Academy of Science for awarding him the Bolyai János Research Scholarship(BO/00393/22)。
文摘Delay is one of the most crucial factors for both pedestrians and car drivers around pedestrian crossings.Drivers often do not yield to pedestrians,which may result in both delay and impatient pedestrian behaviour.This tendency may alter after introducing autonomous vehicles as the vehicles will follow the traffic rules in all cases.This study aims to estimate the delay time alteration at a simple zebra crossing using on-site measures and simulation.Roadside video recordings were carried out in Budapest,Hungary,to obtain the crossing decisions of pedestrian groups based on the approaching vehicle distance.We have determined the accepted vehicle distance vales for pedestrian groups that served as input data for microsimulation modelling.The novelty of the study is that the simulation involved autonomous vehicles that hold preset headways from the leading vehicle.The simulation was designed based on the traffic share of autonomous vehicles and the headways they kept.The main findings are that the travel time and stopping time for cars are higher if the modal share of autonomous vehicles is high.For pedestrians,however,we found a slight decrease in both travel times and stopping times.Moreover,we have proposed modifications to the simulation software(Vissim)to handle distancedependent pedestrian decisions and drivers'failure to give priority.The results can be useful for road operators to estimate the road capacity in the era of autonomous vehicles and for software developers to formulate the simulated and real driving mechanism for autonomous vehicles.
文摘The lane changing decision model(LCDM)is a critical component in semi-and fully-automated driving systems.Recent research has found that the fuzzy inference system(FIS)is a promising approach to implementing LCDMs.To improve the FIS’s performance,this research reviewed the challenges in the development an FIS model to make the yes;nof g decisions in discretionary lane changes.The FIS model was revised to bring its fuzzy inference rules more consistent with the fuzzy membership functions,and its com-position and defuzzification methods more in line with the classical fuzzy logic theory.An equitable test data set with approximately equal number of yes;nof g data points was assembled from the same next generation simulation(NGSIM)data used in the past research.The test results proved that:(1)an LCDM’s performance was dependent on how the yes;nof g decisions in the test data set were manually labeled;(2)separating the fuzzy inference rules into a yesf g group and a nof g group and compute the results sep-arately yielded potentially better decision accuracy.Furthermore,The gene expression pro-gramming model(GEPM)performed better than the improved FIS-based model.The findings led the authors to suggest two possible research directions:(1)add the subject vehicle’s speed as an input to the LCDM and redesign the decision-making model;(2)con-struct models for congested and uncongested traffic separately.The authors further sug-gested the use of instrumented vehicles to collect a set of high-fidelity lane changing data in the naturalistic driving environment.
文摘Pedestrians usually cross the road at mid-block locations in India because of the ease and convenience to reach their destination as compared to intersection locations. It is important to evaluate the pedestrian gap acceptance behavior at mid-block locations because of inadequate vehicular gaps un- der mixed traffic condition, which translates into the pedestrian road crossing behavior. The present study examines the pedestrian gap acceptance behaviour by employing an artificial neural network （ANN） model for understanding the decision making process of pedestrians, i. e. , acceptance or rejec- tion of vehicular gaps at a mid-block location. From the results it has been found that the pedestrian rolling gap, frequency of attempt, vehicular gap size, pedestrian speed change condition and vehicle speed have major role in pedestrian gap acceptance. These results can lead to a better design of pedestrian crossing facilities where adequate gaps are not available in vehicular flow at mid-block crosswalk locations.
