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Truck rollover is a problem that seriously endangers the safety of human life. Under special conditions, when the driver takes a sharp turn, the truck is most prone to rollover. Speed seriously affects the driving stability of the truck in a sharp turn, but the calculation of the safe speed is not accurate enough at present. The aim of this paper is to develop a more accurate safe speed calculation method to avoid the truck rollover in a sharp turn. Firstly, the calculation formula of the rollover threshold was derived based on a theoretical model, then, the simulation tests were carried out. We selected a 4-axle truck with a total weight of 30t as the subject, simulated the dynamic process of the truck rollover in a sharp turn with TruckSim, evaluated the dynamic rollover risk levels of the truck during this process, and verified the accuracy of the simulation results by results of the theoretical model. Finally, by analyzing the steering principle of the vehicle, the safe speed threshold and the limit speed threshold of the truck in a sharp turn were calculated according to the lateral acceleration corresponding to the rollover risk levels. The results show that no matter what the loading condition of the truck is, when the rollover margin is reduced to about 0.15g, the truck just reaches the risk level of critical rollover; the result provides an accurate algorithm for speed thresholds of the truck when turning radius is less than 250 m. The research provides a calculation method for safe speed of trucks from a dynamic perspective. The research results can be applied to the speed warning system of trucks, which can make drivers better control the rollover risk of trucks in the process of driving and improve driving safety.
Tian Xin; Jinliang Xu; Chao Gao; Zhenhua Sun. Research on the speed thresholds of trucks in a sharp turn based on dynamic rollover risk levels. PLoS ONE 2021, 16, 1 .
AMA StyleTian Xin, Jinliang Xu, Chao Gao, Zhenhua Sun. Research on the speed thresholds of trucks in a sharp turn based on dynamic rollover risk levels. PLoS ONE. 2021; 16 (8):1.
Chicago/Turabian StyleTian Xin; Jinliang Xu; Chao Gao; Zhenhua Sun. 2021. "Research on the speed thresholds of trucks in a sharp turn based on dynamic rollover risk levels." PLoS ONE 16, no. 8: 1.
The water film depth is a key variable that affects traffic safety under rainfall conditions. According to the Federal Highway Administration, approximately 5700 people are killed and more than 544 700 people are injured in crashes on wet pavements annually. While several studies have attempted to address water film depth issues by establishing prediction models, a few focused on the relationship among road geometric features, capacity of drainage facilities and water film depth. To ascertain the influence of the geometric features of road and facility drainage capacities on the water film depth, the road geometry features were first classified into four types, and the facility drainage capacities were considered from three aspects in this study. Furthermore, the concept of short-time rainfall grade was proposed according to the results of the field test. Finally, the theoretical prediction model for the water film depth was conceived, based on the geometric features of road and facility drainage capacities with different rainfall intensities. Compared with the traditional regression prediction models, the theoretical prediction model clearly shows the effects of the geometric features of road and facility drainage capacities. When the road drainage facilities have no drainage capacity, the water film depth increases rapidly with the rainfall intensity. This model can be used to predict the water film depth of road surfaces on rainy days, evaluate the effect of rainfall on the driving environment, and provide guidance for determining safety control measures on rainy days.
Shuo Han; Jinliang Xu; Menghua Yan; Sunjian Gao; Xufeng Li; XunJiang Huang; Zhaoxin Liu. Predicting the water film depth: A model based on the geometric features of road and capacity of drainage facilities. PLoS ONE 2021, 16, e0252767 .
AMA StyleShuo Han, Jinliang Xu, Menghua Yan, Sunjian Gao, Xufeng Li, XunJiang Huang, Zhaoxin Liu. Predicting the water film depth: A model based on the geometric features of road and capacity of drainage facilities. PLoS ONE. 2021; 16 (7):e0252767.
Chicago/Turabian StyleShuo Han; Jinliang Xu; Menghua Yan; Sunjian Gao; Xufeng Li; XunJiang Huang; Zhaoxin Liu. 2021. "Predicting the water film depth: A model based on the geometric features of road and capacity of drainage facilities." PLoS ONE 16, no. 7: e0252767.
Recently, subways have become an important part of public transportation and have developed rapidly in China. In the subway station setting, pedestrians mainly rely on visual short-term memory to obtain information on how to travel. This research aimed to explore the short-term memory capacities and the difference in short-term memory for different information for Chinese passengers regarding subway signs. Previous research has shown that people’s general short-term memory capacity is approximately four objects and that, the more complex the information, the lower people’s memory capacity. However, research on the short-term memory characteristics of pedestrians for subway signs is scarce. Hence, based on the STM theory and using 32 subway signs as stimuli, we recruited 120 subjects to conduct a cognitive test. The results showed that passengers had a different memory accuracy for different types of information in the signs. They were more accurate regarding line number and arrow, followed by location/text information, logos, and orientation. Meanwhile, information type, quantity, and complexity had significant effects on pedestrians’ short-term memory capacity. Finally, according to our results that outline the characteristics of short-term memory for subway signs, we put forward some suggestions for subway signs. The findings will be effective in helping designers and managers improve the quality of subway station services as well as promoting the development of pedestrian traffic in such a setting.
Haoru Li; Jinliang Xu; Xiaodong Zhang; Fangchen Ma. How Do Subway Signs Affect Pedestrians’ Wayfinding Behavior through Visual Short-Term Memory? Sustainability 2021, 13, 6866 .
AMA StyleHaoru Li, Jinliang Xu, Xiaodong Zhang, Fangchen Ma. How Do Subway Signs Affect Pedestrians’ Wayfinding Behavior through Visual Short-Term Memory? Sustainability. 2021; 13 (12):6866.
Chicago/Turabian StyleHaoru Li; Jinliang Xu; Xiaodong Zhang; Fangchen Ma. 2021. "How Do Subway Signs Affect Pedestrians’ Wayfinding Behavior through Visual Short-Term Memory?" Sustainability 13, no. 12: 6866.
As the facility with the highest utilization rate in the expressway service area, the toilet has the greatest influence on the crowd gathering degree in the expressway service area. In order to study the scale and location of toilets in the Meicun service area, this paper conducts a field survey on the service area of Meicun by means of video recording and crowd tracking questionnaire survey. Through the investigation, the key data such as the probability of customers using toilet and toilet turnover rate were obtained. Based on this, the flow model of the crowd in the high-speed service area is established by using the simulation software of Anylogic. In the simulation, the scale and location of the toilet facilities in the high-speed service area are analyzed and evaluated according to the number of people using the toilet at the same time. The results show the influence of different toilet layout on the efficiency of toilet use and the degree of crowd gathering, and prove that double toilets are more efficient than single toilets, disperse the flow of people, reduce the degree of crowd gathering and avoid crowd crowding.
Xufeng Li; Jinliang Xu; Sunjian Gao. The Analysis of Toilet Use Efficiency in Expressway Service Area Based on Anylogic. IOP Conference Series: Earth and Environmental Science 2021, 634, 012140 .
AMA StyleXufeng Li, Jinliang Xu, Sunjian Gao. The Analysis of Toilet Use Efficiency in Expressway Service Area Based on Anylogic. IOP Conference Series: Earth and Environmental Science. 2021; 634 (1):012140.
Chicago/Turabian StyleXufeng Li; Jinliang Xu; Sunjian Gao. 2021. "The Analysis of Toilet Use Efficiency in Expressway Service Area Based on Anylogic." IOP Conference Series: Earth and Environmental Science 634, no. 1: 012140.
Understanding the behavior characteristics of highway drivers in rainy weather is of great significance to traffic safety. Based on the driving test in the middle rain environment, this paper uses the method of combining the sports index and the driver's behavior to study the characteristics of the driver's behavior in the middle rain environment. A total of 15 drivers were recruited in this test to observe the impact of the moderate rain environment on the drivers, and to analyze the correlation of various indicators to summarize the vehicle operation rules on the straight road section under the moderate rain environment. The results of the study show that the speed on straight road sections is generally higher in moderate rain weather, and the driver's recognition time for signage is longer than in sunny day. Finally, according to the behavior characteristics of drivers in rainy days, the corresponding traffic safety measures are put forward.
Yufei Sun; Jinliang Xu. Research on Drivers’ Behavior Characteristics of Expressway Straight Section under Moderate Rainfall. IOP Conference Series: Earth and Environmental Science 2021, 634, 012134 .
AMA StyleYufei Sun, Jinliang Xu. Research on Drivers’ Behavior Characteristics of Expressway Straight Section under Moderate Rainfall. IOP Conference Series: Earth and Environmental Science. 2021; 634 (1):012134.
Chicago/Turabian StyleYufei Sun; Jinliang Xu. 2021. "Research on Drivers’ Behavior Characteristics of Expressway Straight Section under Moderate Rainfall." IOP Conference Series: Earth and Environmental Science 634, no. 1: 012134.
Predicting vehicle carbon emissions on vertical curve sections can provide guidance for low-carbon vertical profile designs. Given that the influence of vertical curve design indicators on the fuel consumption and CO2 emissions of vehicles are underexplored, this study filled this research gap by establishing a theoretical carbon emission model of vehicles on vertical curve sections. The carbon emission model was established based on Xu’s vehicle energy conversion model, the conversion model of energy, fuel consumption, and CO2 emissions. The accuracy of the theoretical carbon emission model and the CO2 emission rules on vertical curve sections were verified by field test results. Field tests were carried out on flat sections, longitudinal slope sections, and various types of vertical curve sections, with five common types of vehicles maintaining cruising speed. The carbon emission rate effects on the vertical curve are closely related to the gradient and irrelevant of the radius. On the vertical profile composed with downhill/asymmetric/symmetrical vertical curve with a gradient greater than the balance gradient, the carbon emission rate is determined by the gradient and radius. The influence of the gradient on carbon emissions of vehicle on these vertical profiles was more significant than the radius. The radius is irrelevant to the carbon emission rate on the other forms of vertical profile. These results may benefit highway designers and engineers by providing guidelines regarding the environmental effects of highway vertical curve indexes.
Yaping Dong; Jinliang Xu. Estimation of Vehicle Carbon Emissions in China Accounting for Vertical Curve Effects. Mathematical Problems in Engineering 2020, 2020, 1 -20.
AMA StyleYaping Dong, Jinliang Xu. Estimation of Vehicle Carbon Emissions in China Accounting for Vertical Curve Effects. Mathematical Problems in Engineering. 2020; 2020 ():1-20.
Chicago/Turabian StyleYaping Dong; Jinliang Xu. 2020. "Estimation of Vehicle Carbon Emissions in China Accounting for Vertical Curve Effects." Mathematical Problems in Engineering 2020, no. : 1-20.
Carbon emissions are the primary reason that contributes to global warming. The gradient has a significant impact on the carbon dioxide (CO2) emissions produced by trucks. The aim of the current paper is to propose a carbon emission quantification model for diesel trucks on longitudinal slope sections and investigate the influence of gradient on the carbon emissions of trucks for use in the low-carbon highway design. The law of conservation of mechanical energy, the first law of thermodynamics, and the vehicle longitudinal dynamics theory were adopted for deriving the carbon emission model of the trucks on the flat, uphill, downhill and round-trip longitudinal slope segments. Three kinds of common trucks were chosen to conduct the field test. Following the test data, the model demonstrates a high accuracy. The minimum gradient which is expected to impact carbon emissions of trucks on the round-trip longitudinal slope sections was the balance gradient as revealed. The gradient of the longitudinal slope is required to be avoided to be greater in comparison with the balance gradient for the achievement of the two-way traffic low carbon operation on a highway. The results of this study are valuable to researchers interested in low carbon road design and low carbon transportation control.
Yaping Dong; Jinliang Xu; Chenwei Gu. Modelling carbon emissions of diesel trucks on longitudinal slope sections in China. PLOS ONE 2020, 15, e0234789 .
AMA StyleYaping Dong, Jinliang Xu, Chenwei Gu. Modelling carbon emissions of diesel trucks on longitudinal slope sections in China. PLOS ONE. 2020; 15 (6):e0234789.
Chicago/Turabian StyleYaping Dong; Jinliang Xu; Chenwei Gu. 2020. "Modelling carbon emissions of diesel trucks on longitudinal slope sections in China." PLOS ONE 15, no. 6: e0234789.
The geometric longitudinal slope line of a given road significantly effects the carbon emissions of vehicles traversing it. This study was conducted to explore the carbon emission rules of passenger cars on various highway slopes. The law of conservation of mechanical energy, the first law of thermodynamics and the vehicle longitudinal dynamics theory were utilized to determine the influence of slope design indicators on fuel consumption. The energy conversion, fuel consumption, and carbon emission models of passenger cars on a flat straight road, uphill road, and downhill road sections were derived accordingly. Two types of passenger cars were selected for analysis. A field test was carried out to verify the proposed model where the vehicle maintained a cruise speed on flat straight road, uphill road and downhill road with equal gradient and mileage, and continuous longitudinal slope to gather fuel consumption data. The proposed model showed strong accuracy and a maximum error of 9.97%. The main factor affecting the vehicle’s carbon emissions on the continuous longitudinal slope was found to be the average gradient. For a round-trip longitudinal slope with a small gradient, the main factor affecting the vehicle’s carbon emissions is speed: higher speed results in higher carbon emissions. The results of this study are likely to provide the data for support and a workable reference for the low-carbon highway design and operation.
Jinliang Xu; Yaping Dong; Menghua Yan. A Model for Estimating Passenger-Car Carbon Emissions that Accounts for Uphill, Downhill and Flat Roads. Sustainability 2020, 12, 2028 .
AMA StyleJinliang Xu, Yaping Dong, Menghua Yan. A Model for Estimating Passenger-Car Carbon Emissions that Accounts for Uphill, Downhill and Flat Roads. Sustainability. 2020; 12 (5):2028.
Chicago/Turabian StyleJinliang Xu; Yaping Dong; Menghua Yan. 2020. "A Model for Estimating Passenger-Car Carbon Emissions that Accounts for Uphill, Downhill and Flat Roads." Sustainability 12, no. 5: 2028.
A new concept of Highway Node Acceptance Capacity (HNAC) is proposed in this paper inspired by a field data observation. To understand HNAC in microscopic view, boundary condition of successful merging is found using car-following behaviours and lane-changing rules, which could also explain traffic oscillations. In macroscopic view, linear positive relationship between HNAC and background traffic volume is obtained based on moving bottleneck. To determine the explicit form of the relationship, data simulation considering car-following behaviours and traffic flow theory is used. In the results, the synchronization phenomenon of oscillation in on-ramp (with respect to main road) and intersected road is found. The explicit equation of HNAC is determined based on standard deviation and correlation coefficient analysis, and also proved to be accurate with model validation, which is helpful in studies related to propagation mechanism of traffic emergencies on highway network.
Xingliang Liu; Jinliang Xu; Yaping Dong; Han Ru; Zhihao Duan. Defining Highway Node Acceptance Capacity (HNAC): Theoretical Analysis and Data Simulation. Journal of Advanced Transportation 2020, 2020, 1 -16.
AMA StyleXingliang Liu, Jinliang Xu, Yaping Dong, Han Ru, Zhihao Duan. Defining Highway Node Acceptance Capacity (HNAC): Theoretical Analysis and Data Simulation. Journal of Advanced Transportation. 2020; 2020 ():1-16.
Chicago/Turabian StyleXingliang Liu; Jinliang Xu; Yaping Dong; Han Ru; Zhihao Duan. 2020. "Defining Highway Node Acceptance Capacity (HNAC): Theoretical Analysis and Data Simulation." Journal of Advanced Transportation 2020, no. : 1-16.
Road geometric design is a key factor impacting driving safety and efficiency. In highway profile design, speed reduction is used to determine critical length of grade. Previous research generally concentrated on the relationship between speed reduction and crash involvement rate to establish the recommended value. Limited research results have been reported at this point concerning speed reduction and traffic efficiency. This study aims to fill the gap by investigating tolerable speed reduction with different vertical slopes considering traffic efficiency. Firstly, appropriate experimental sections were determined after field survey. Traffic data including vehicle count, timely speed, vehicle type, and headway time were then collected on an expressway in Shaanxi Province. The associated traffic efficiency was derived from traffic volume and average speed. After this, the modeling between speed reduction and traffic efficiency was processed with different slopes. The correlation between speed reduction and traffic efficiency was therefore verified. Finally, the prediction model of optimum speed reduction concerning traffic efficiency under different vertical slopes was introduced. It was found that the critical length of grade can be longer with traffic efficiency as the major design control incorporated with slopes of 3–3.5%. The existing regulation in critical length of grade at 3.5–5% can benefit both safety and efficiency. The findings can provide a reference for vertical alignment design, leading to high-efficiency road systems.
Xiaodong Zhang; Jinliang Xu; Qianqian Liang; Fangchen Ma. Modeling Impacts of Speed Reduction on Traffic Efficiency on Expressway Uphill Sections. Sustainability 2020, 12, 587 .
AMA StyleXiaodong Zhang, Jinliang Xu, Qianqian Liang, Fangchen Ma. Modeling Impacts of Speed Reduction on Traffic Efficiency on Expressway Uphill Sections. Sustainability. 2020; 12 (2):587.
Chicago/Turabian StyleXiaodong Zhang; Jinliang Xu; Qianqian Liang; Fangchen Ma. 2020. "Modeling Impacts of Speed Reduction on Traffic Efficiency on Expressway Uphill Sections." Sustainability 12, no. 2: 587.
Large vehicles impact the quality of traffic flow. To predict the impact of large-scale vehicles on the average speed of traffic flow, vehicle speeds under different vehicle mixing rates were collected through field observations. A laser roadside traffic survey instrument with automatic vehicle type identification functionality was used to collect cross section traffic flow data. The v/C ratio, large vehicle mixing rate, and average speed of traffic were calculated for each data set. A total of 158 traffic flow data sets were captured and divided into three groups according to the v/C ratio of the expressway. The v/C ratio ranges of the three groups are v/C≤0.35, 0.35
Chao Gao; Jinliang Xu; Xingli Jia; Yaping Dong; Han Ru. Influence of Large Vehicles on the Speed of Expressway Traffic Flow. Advances in Civil Engineering 2020, 2020, 1 -9.
AMA StyleChao Gao, Jinliang Xu, Xingli Jia, Yaping Dong, Han Ru. Influence of Large Vehicles on the Speed of Expressway Traffic Flow. Advances in Civil Engineering. 2020; 2020 ():1-9.
Chicago/Turabian StyleChao Gao; Jinliang Xu; Xingli Jia; Yaping Dong; Han Ru. 2020. "Influence of Large Vehicles on the Speed of Expressway Traffic Flow." Advances in Civil Engineering 2020, no. : 1-9.
To reduce the impact of a natural or man-made disaster, an evacuation is often implemented to transfer the population in the potentially impacted area to a safe zone. Evacuation is an effective measure for dealing with emergency events. This paper presents a multinomial logit model for modal choice behavior in a short-notice emergency evacuation, which incorporates spatial indicators into the utility function. The study examined the determinants of evacuees’ modal choice for three evacuation distances and analyzed determinants impacting the mechanism of the modal choice decision process. The data collected in Xi’an was used to provide empirical evidence for the relationship between spatial indicators and modal choice behavior. The findings of this study will help emergency planners and policy-makers develop strategies for evacuation planning and will enable a better understanding of emergency modal choice behaviors.
Zhihao Duan; Jinliang Xu; Han Ru; Yaping Dong; Xingliang Liu. Analysis of Emergency Evacuation Modal Choice Behavior with Spatial Indicators: Case Study in Xi’an, China. Sustainability 2019, 11, 7023 .
AMA StyleZhihao Duan, Jinliang Xu, Han Ru, Yaping Dong, Xingliang Liu. Analysis of Emergency Evacuation Modal Choice Behavior with Spatial Indicators: Case Study in Xi’an, China. Sustainability. 2019; 11 (24):7023.
Chicago/Turabian StyleZhihao Duan; Jinliang Xu; Han Ru; Yaping Dong; Xingliang Liu. 2019. "Analysis of Emergency Evacuation Modal Choice Behavior with Spatial Indicators: Case Study in Xi’an, China." Sustainability 11, no. 24: 7023.
In the metro operation environment, guiding signs provide direction and route conversion instructions to pedestrians. In metro stations with massive passenger flow, the rationality of sign setting would exert distinct effects on the efficiency of passenger flow. Currently, most studies on guiding signs focus on architecture, aesthetics and simulation. However, perspectives from humanization of pedestrian guidance signs such as pedestrian behavior needs and pedestrian cognition were seldom proposed. In this paper, the microscopic behavior characteristics data of pedestrians at different positions in typical metro stations were collected through pedestrian tracking experiments. After analyzing the characteristics of pedestrians’ microscopic behavior in metro stations, otherness of walking speed was found out among pedestrians in different types of passageways. The walking speed of pedestrians in closed-type passageways is higher than other types. Moreover, pedestrian speed at the stairs adjacent to the platform is higher than that at the stairs not adjacent to the platform. With the increase of crowd density, the change of walking speed of pedestrians can be represented by a unimodal curve. Finally, the key points of optimal setting of guiding signs in different regions and different periods were obtained according to the result analysis of the experiment. The research results of this paper can provide theoretical support and technical guidance for the optimal establishment of pedestrian guiding signs in metro stations with massive passenger flow.
Bin Lei; Jinliang Xu; Menghui Li; Haoru Li; Jin Li; Zhen Cao; Li Haoru; Yuan Zhang. Enhancing Role of Guiding Signs Setting in Metro Stations with Incorporation of Microscopic Behavior of Pedestrians. Sustainability 2019, 11, 6109 .
AMA StyleBin Lei, Jinliang Xu, Menghui Li, Haoru Li, Jin Li, Zhen Cao, Li Haoru, Yuan Zhang. Enhancing Role of Guiding Signs Setting in Metro Stations with Incorporation of Microscopic Behavior of Pedestrians. Sustainability. 2019; 11 (21):6109.
Chicago/Turabian StyleBin Lei; Jinliang Xu; Menghui Li; Haoru Li; Jin Li; Zhen Cao; Li Haoru; Yuan Zhang. 2019. "Enhancing Role of Guiding Signs Setting in Metro Stations with Incorporation of Microscopic Behavior of Pedestrians." Sustainability 11, no. 21: 6109.
Understanding the relationship between speed limit and characteristic speed of expressway traffic flow is of great significance for formulating a reasonable speed limit scheme and improving highway safety and transportation efficiency. In this study, the speed data of the same traffic flow passing through speed limits of 80, 100, and 120 km/h were continuously collected through a field test. The 85th, 15th, and 50th percentile speeds were considered the characteristic speed parameters of the traffic flow. A regression analysis was performed to establish a relationship between the characteristic speed parameters of the traffic flow and the speed limit. Under a free-flow state, the characteristic speed exhibited a strong linear relationship with the speed limit, where the variation ranges of the 85th and 50th percentile speeds were approximately consistent with that of the speed limit. However, a slight inconsistency was found for the 15th percentile speed, which was approximately half the speed limit increase; under a non-free-flow state, the correlation between the speed limit and the vehicle speed was no longer significant.
Jie Yang; Jinliang Xu; Chao Gao; Guohua Bai; Linfang Xie; Menghui Li. Modeling of the Relationship Between Speed Limit and Characteristic Speed of Expressway Traffic Flow. Sustainability 2019, 11, 4621 .
AMA StyleJie Yang, Jinliang Xu, Chao Gao, Guohua Bai, Linfang Xie, Menghui Li. Modeling of the Relationship Between Speed Limit and Characteristic Speed of Expressway Traffic Flow. Sustainability. 2019; 11 (17):4621.
Chicago/Turabian StyleJie Yang; Jinliang Xu; Chao Gao; Guohua Bai; Linfang Xie; Menghui Li. 2019. "Modeling of the Relationship Between Speed Limit and Characteristic Speed of Expressway Traffic Flow." Sustainability 11, no. 17: 4621.
Truck’s climbing performance is an important consideration in traffic safety, efficiency, and highway geometric design. With the infrastructure development in high-altitude area in China, more attention needs to be paid on truck’s climbing performance in such area. In this article, truck’s climbing speed in high-altitude area was examined through field tests on different grade sections at different altitudes. Truck’s speed-distance curves were built at different altitudes and the impact of altitude on truck’s climbing speed was explored based on the test results. It was shown that, within the altitude range of 3000~5000m, altitude had an obvious influence on test truck’s decelerating and accelerating performance. Truck’s speed decreased faster on steep grades and increased slower on gentle grades with the increase of the altitude. Also, the stable speed that test truck could maintain on a certain grade was lower at a higher altitude. In addition, test truck’s theoretical speed-distance curves at the sea level were estimated through truck’s dynamic model. Compared with the theoretical crawl speed, a negative effect of altitude change (from 0 to the altitude above 3000 m) was found on truck’s climbing performance.
Tian Lei; Jinliang Xu; Xingli Jia; Leyu Wei; Lin Tian. Impact of High-Altitude on Truck’s Climbing Speed: Case study in Qinghai-Tibet Plateau Area in China. Journal of Advanced Transportation 2019, 2019, 1 -14.
AMA StyleTian Lei, Jinliang Xu, Xingli Jia, Leyu Wei, Lin Tian. Impact of High-Altitude on Truck’s Climbing Speed: Case study in Qinghai-Tibet Plateau Area in China. Journal of Advanced Transportation. 2019; 2019 ():1-14.
Chicago/Turabian StyleTian Lei; Jinliang Xu; Xingli Jia; Leyu Wei; Lin Tian. 2019. "Impact of High-Altitude on Truck’s Climbing Speed: Case study in Qinghai-Tibet Plateau Area in China." Journal of Advanced Transportation 2019, no. : 1-14.
Heavy-duty trucks contribute a significant component of all transportation in cargo terminals, such as Shaanxi Province, China. The emissions from these vehicles are the primary source of carbon emissions during highway operations. While several studies have attempted to address emission issues by improving traffic operations, a few focused on the relationship between emissions and highway geometric design, especially for heavy-duty trucks. The primary goal of this research was to understand the impact of circular curve on carbon dioxide (CO2) emissions produced by heavy-duty diesel trucks. Firstly, appropriate parameters were specified in MOVES (motor vehicle emission simulator) model according to the geometrical characteristics. Fuel consumption, speed and location data were collected by hiring five skilled drivers on the automotive proving ground located at Chang’an University, Shaanxi Province. The associated carbon emission data were derived from fuel consumption data by applying the IPCC (Intergovernmental Panel on Climate Change) method. After this, the applicability of MOVES model was verified by the field experiment. Moreover, a multiple regression model for CO2 emissions incorporated with roadway segment radius, circular curve length, and initial vehicle speed was established with data generated by the MOVES model. The proposed CO2 emission model was also verified by field experiment with relative error of 6.17%. It was found that CO2 emission had monotone decreasing property with radius increasing, and the minimum radius that influenced diesel CO2 emission was 550 m. The proposed quantitative CO2 emission model can provide a reference for low-carbon highway design, leading to environment-friendly transportation construction.
Xiaodong Zhang; Jinliang Xu; Menghui Li; Qunshan Li; Lan Yang. Modeling Impacts of Highway Circular Curve Elements on Heavy-Duty Diesel Trucks’ CO2 Emissions. International Journal of Environmental Research and Public Health 2019, 16, 2514 .
AMA StyleXiaodong Zhang, Jinliang Xu, Menghui Li, Qunshan Li, Lan Yang. Modeling Impacts of Highway Circular Curve Elements on Heavy-Duty Diesel Trucks’ CO2 Emissions. International Journal of Environmental Research and Public Health. 2019; 16 (14):2514.
Chicago/Turabian StyleXiaodong Zhang; Jinliang Xu; Menghui Li; Qunshan Li; Lan Yang. 2019. "Modeling Impacts of Highway Circular Curve Elements on Heavy-Duty Diesel Trucks’ CO2 Emissions." International Journal of Environmental Research and Public Health 16, no. 14: 2514.
Speed dispersion is an important indicator to portray the quality of traffic flow and is closely related to the road safety operation level. In order to clarify the influence of posted speed limits on the dispersion of traffic flow speed, three sections with speed limits of 80 km/h, 100 km/h and 120 km/h on the same expressway were selected for observation, and traffic volume, speed and other parameters were collected. The characteristic speeds, such as average speed, V15 and V85, were evaluation indicators, where V15 and V85 are the speeds of the 15th and 85th percentiles measured at the feature points of the road when the traffic is in a free-flow state and the weather is good. The relationship between different posted speed limit values and the above indicators was analyzed using the statistical analysis software, SPSS. The results show that the speed limit has a high correlation with the average speed of traffic flow, V15 and V85 in free-flow state, with the coefficient of determination being as high as 0.84, 0.85 and 0.92, respectively. In the restricted flow state, the factors affecting the driver’s driving speed are mainly the decrease in driving freedom caused by the increase of traffic volume rather than the speed limit value. In a free-flow state, when the posted speed limit is increased and the average speed and the V85 also increased by approximately the same magnitude. The posted speed limit values of 80 km/h, 100 km/h and 120 km/h correspond to the 90, 88 and 97 percentile speeds of the traffic flow, respectively. The higher the speed limit is, the larger the speed difference between V15 and V85 becomes. The results of the study are very useful for rationally determining the speed limit scheme under different traffic flows.
Chao Gao; Jinliang Xu; Qunshan Li; Jie Yang. The Effect of Posted Speed Limit on the Dispersion of Traffic Flow Speed. Sustainability 2019, 11, 3594 .
AMA StyleChao Gao, Jinliang Xu, Qunshan Li, Jie Yang. The Effect of Posted Speed Limit on the Dispersion of Traffic Flow Speed. Sustainability. 2019; 11 (13):3594.
Chicago/Turabian StyleChao Gao; Jinliang Xu; Qunshan Li; Jie Yang. 2019. "The Effect of Posted Speed Limit on the Dispersion of Traffic Flow Speed." Sustainability 11, no. 13: 3594.
Contraflow is a common traffic strategy used to improve the capacity of outbound roads during mass evacuation. Previous studies have focused on the contraflow network configuration, travel time, and number of evacuated vehicles on a macroscopic level. Only a few researchers have considered microscopic factors, such as the contraflow characteristics and moving bottlenecks caused by coaches and trucks. In this study, the effects of the contraflow strategy were investigated through field experiments and traffic simulations. Traffic data were collected from highway segments where trucks were forbidden under regular and contraflow conditions for analysis of the traffic characteristics and the effects of coach moving bottlenecks. The results demonstrate that the capacity and flow speed of contraflow lanes are lower than normal lanes, owing to the narrow cross sections and unfamiliar driving environment. The moving bottlenecks also reduced the speed of passenger car platoons by approximately 5–20 km/h. Four different contraflow schemes were developed and evaluated by Vissim to examine their effectiveness for minimizing the effect of truck moving bottlenecks. The findings revealed an obvious negative effect of trucks on the performance of the contraflow strategy, indicating the need for specific schemes when the truck ratio is large.
Leyu Wei; Jinliang Xu; Tian Lei; Menghui Li; Xingliang Liu; Haoru Li. Simulation and Experimental Analyses of Microscopic Traffic Characteristics under a Contraflow Strategy. Applied Sciences 2019, 9, 2651 .
AMA StyleLeyu Wei, Jinliang Xu, Tian Lei, Menghui Li, Xingliang Liu, Haoru Li. Simulation and Experimental Analyses of Microscopic Traffic Characteristics under a Contraflow Strategy. Applied Sciences. 2019; 9 (13):2651.
Chicago/Turabian StyleLeyu Wei; Jinliang Xu; Tian Lei; Menghui Li; Xingliang Liu; Haoru Li. 2019. "Simulation and Experimental Analyses of Microscopic Traffic Characteristics under a Contraflow Strategy." Applied Sciences 9, no. 13: 2651.
Traffic flow patterns severely impact vehicle carbon emissions. A field test was conducted in this study to obtain fuel consumption and traffic volume data under various traffic flow patterns and to explore the relationship between traffic flow patterns and vehicle carbon emissions. Carbon emission data were obtained via the indirect carbon emission accounting method proposed by the Intergovernmental Panel on Climate Change. Carbon emission prediction models for diesel trucks and gasoline passenger cars were established respectively with volume to capacity ratio as an explanatory variable. The results show that carbon emissions are highest under the congested flow conditions, followed by unstable flow, free flow, and steady flow. The relationship between the volume to capacity ratio and carbon emissions is a cubic curve function. The carbon emissions of trucks and passenger cars with a volume to capacity ratio of 0.4 to 0.5 are relatively small. The proposed carbon emissions models effectively quantify the carbon emissions of vehicles under different traffic flow patterns. The results of this study may provide data to support and a workable reference for expressway operation management and future low-carbon expressway expansion construction projects.
Yaping Dong; Jinliang Xu; Xingliang Liu; Chao Gao; Han Ru; Zhihao Duan. Carbon Emissions and Expressway Traffic Flow Patterns in China. Sustainability 2019, 11, 2824 .
AMA StyleYaping Dong, Jinliang Xu, Xingliang Liu, Chao Gao, Han Ru, Zhihao Duan. Carbon Emissions and Expressway Traffic Flow Patterns in China. Sustainability. 2019; 11 (10):2824.
Chicago/Turabian StyleYaping Dong; Jinliang Xu; Xingliang Liu; Chao Gao; Han Ru; Zhihao Duan. 2019. "Carbon Emissions and Expressway Traffic Flow Patterns in China." Sustainability 11, no. 10: 2824.
Owing to its mathematical elegance and empirical accuracy, the speed-density model is critical in solving macroscopic traffic problems. This study developed an improved general-logistic-based speed-density model, which is a new method in macroscopic traffic flow theory. This article extensively discusses the properties of the general-logistic-based speed-density model. The physical meanings and values of all the parameters were determined based on the effect of heavy vehicles and the method for the linear and nonlinear regression analysis. The accuracy and versatility of the developed model were also found to be excellent based on the field data and relative error.
Xingliang Liu; Jinliang Xu; Menghui Li; Leyu Wei; Han Ru. General-Logistic-Based Speed-Density Relationship Model Incorporating the Effect of Heavy Vehicles. Mathematical Problems in Engineering 2019, 2019, 1 -10.
AMA StyleXingliang Liu, Jinliang Xu, Menghui Li, Leyu Wei, Han Ru. General-Logistic-Based Speed-Density Relationship Model Incorporating the Effect of Heavy Vehicles. Mathematical Problems in Engineering. 2019; 2019 ():1-10.
Chicago/Turabian StyleXingliang Liu; Jinliang Xu; Menghui Li; Leyu Wei; Han Ru. 2019. "General-Logistic-Based Speed-Density Relationship Model Incorporating the Effect of Heavy Vehicles." Mathematical Problems in Engineering 2019, no. : 1-10.