In order to provide important parameters for schedule designing, decision-making bases for transit operation management and references for passengers traveling by bus, bus transit travel time reliability is analyzed a...In order to provide important parameters for schedule designing, decision-making bases for transit operation management and references for passengers traveling by bus, bus transit travel time reliability is analyzed and evaluated based on automatic vehicle location （AVL） data. Based on the statistical analysis of the bus transit travel time, six indices including the coefficient of variance, the width of travel time distribution, the mean commercial speed, the congestion frequency, the planning time index and the buffer time index are proposed. Moreover, a framework for evaluating bus transit travel time reliability is constructed. Finally, a case study on a certain bus route in Suzhou is conducted. Results show that the proposed evaluation index system is simple and intuitive, and it can effectively reflect the efficiency and stability of bus operations. And a distinguishing feature of bus transit travel time reliability is the temporal pattern. It varies across different time periods.展开更多
Proper braking force distribution strategies can improve both stability and economy performance of hybrid electric vehicles,which is prominently proved by many studies.To achieve better dynamic stable performance and ...Proper braking force distribution strategies can improve both stability and economy performance of hybrid electric vehicles,which is prominently proved by many studies.To achieve better dynamic stable performance and higher energy recovery efficiency,an effective braking control strategy for hybrid electric buses(HEB)based on vehicle mass and road slope estimation is proposed in this paper.Firstly,the road slope and the vehicle mass are estimated by a hybrid algorithm of extended Kalman filter(EKF)and recursive least square(RLS).Secondly,the total braking torque of HEB is calculated by the sliding mode controller(SMC),which uses the information of brake intensity,whole vehicle mass,and road slope.Finally,comprehensively considering driver’s braking intention and regulations of the Economic Commission for Europe(ECE),the optimal proportional relationship between regenerative braking and pneumatic braking is obtained.Furthermore,related simulations and experiments are carried out on the hardware-in-the-loop test bench.Results show that the proposed strategy can effectively improve the braking performance and increase the recovered energy through precise control of the braking torque.展开更多
Improving bus travel time reliability can attract more commuters to use bus transit,and therefore reduces the share of cars and alleviates trafc congestion.This paper formulates a new bus travel time reliability metri...Improving bus travel time reliability can attract more commuters to use bus transit,and therefore reduces the share of cars and alleviates trafc congestion.This paper formulates a new bus travel time reliability metric that jointly considers two stochastic processes:the in-stop waiting process and in-vehicle travel time process,and the bus travel time reliability function is calculated by the convolution of independent events’probabilities.The new reliability metric is defned as the probability when bus travel time is less than a certain threshold and can be used in both conditions with and without bus transfer.Next,Automatic Vehicle Location(AVL)data of the city of Harbin is used to demonstrate the applicability of the proposed method.Results show that factors such as weather,day of the week,departure time,travel distance,and the distance from the boarding stop to the bus departure station can signifcantly afect the travel time reliability.Then,a case with low bus departure frequency is analyzed to show the impact of travelers’arrival distribution on their bus travel time reliability.Further,it is demonstrated that the travel time reliabilities of two bus transfer schemes of the same Origin–Destination(O–D)pair can have signifcantly diferent patterns.Understanding the bus travel time reliability pattern of the alternative bus routes can help passengers to choose a more reliable bus route under diferent conditions.The proposed bus travel time reliability metric is tested to be sensitive to the efect of diferent factors and can be applied in bus route recommendation,bus service evaluation,and optimization.展开更多
This paper introduces and analyzes Korea＇s NGV （natural gas vehicles） policy for soot-free bus fleet which intends to promote CNG （compressed natural gas） bus in metropolitan area for the reduction of air polluti...This paper introduces and analyzes Korea＇s NGV （natural gas vehicles） policy for soot-free bus fleet which intends to promote CNG （compressed natural gas） bus in metropolitan area for the reduction of air pollution from road sector. At the early stage, Korean goverrmaent established various supporting policy systems to encourage public transportation companies to purchase CNG buses as a means to replace diesel buses. It was evaluated as very successful with making net economic benefit of CNG bus promotion policy. During the 2nd stage, Korean government implemented CNG hybrid bus promotion policy to further reduce both air pollution and greenhouse gas. Now, a new social demand for the vehicles is zero-emission vehicles. The author asserts that current FCEV （fuel cell electric vehicle） should be considered as an alternative to zero-emission vehicles in Korea and suggests policy recommendation for the promotion of FCEV by referring the current CNG bus promotion policy in public transportation sector.展开更多
It is of increasing importance to design and implement vehicle networks for transferring information between electrical control units on Hybrid Electrical Vehicle （HEV）. This paper presents a scheme of using Control...It is of increasing importance to design and implement vehicle networks for transferring information between electrical control units on Hybrid Electrical Vehicle （HEV）. This paper presents a scheme of using Controller Area Network （CAN） technology to realize communication and datasharing between the electrical units on the HEV. The principle and communication protocol of Electrical Control Units （ECU） CAN node are introduced. By considering different sensitivity of the devices to the latency of data transportation, a new design procedure is proposed for the purpose of simplifying network codes and wiring harness, reducing assembly space and weight, improving assembly efficiency, and enhancing fault-diagnose in auto networks.展开更多
Based on the development demand of electric vehicles, this paper studies the communication network in electric vehicles based on CAN bus after analyzing the LCD (liquid crystal display) in electric vehicles and the st...Based on the development demand of electric vehicles, this paper studies the communication network in electric vehicles based on CAN bus after analyzing the LCD (liquid crystal display) in electric vehicles and the status quo of research and development trend about communication network. This system uses TMS320LF2407 DSP as the controller of the control system about central signals. It has also developed the LCD system based on CAN bus and the experiment platform which is applied pure electric vehicles.展开更多
Hanoi’s rapid urbanization has led to a surge in private vehicle ownership, particularly motorcycles, amidst inadequate public transportation infrastructure. Despite government efforts, many still prefer motorized tr...Hanoi’s rapid urbanization has led to a surge in private vehicle ownership, particularly motorcycles, amidst inadequate public transportation infrastructure. Despite government efforts, many still prefer motorized transport, citing mobility and safety concerns, exacerbated by insufficient pedestrian infrastructure. This study examines the motivations behind this reliance on motorized vehicles, particularly motorcycles, in Hanoi. Findings reveal safety and convenience as primary factors driving motorized transport use, especially for accessing bus stations. Economic incentives could promote non-motorized travel and public transport adoption. Policy implications highlight the importance of addressing economic factors and improving access infrastructure to manage motorized vehicle reliance and foster sustainable urban mobility in Hanoi.展开更多
Vehicle rollover, and its resulting fatalities, is an actively researched topic especially for multi-axle vehicles in the field of vehicle dynamics and control. This paper first presents a new rollover index for a tri...Vehicle rollover, and its resulting fatalities, is an actively researched topic especially for multi-axle vehicles in the field of vehicle dynamics and control. This paper first presents a new rollover index for a triaxle bus to accurately evaluate its rollover possibility and then discusses the influence laws of the vehicle rollover dynamics to explore the mechanism of its stability. First, a six degree of freedom rollover model of the triaxle bus is developed, including lateral, yaw, roll motion of the sprung mass of the front/rear axle, and roll motion of the unsprung mass of the front/rear axle. Next, some key parameters of the vehicle rollover model are identified. A new rollover index is deduced according to the basics of vehicle dynamics, to predict vehicle rollover risk for the triaxle bus, which is verified by TruckSim. Furthermore, the influence laws of vehicle rollover dynamics by vehicle parameters and road parameters are discussed based on the simulation results. More importantly, the results show that the new method of modeling can precisely describe the rollover dynamics of the studied bus, and the proposed new index can e ectively evaluate the rollover possibility. Therefore, this study provides a theoretical basis to improve anti-rollover ability for triaxle buses.展开更多
Retrofitting older vehicles with diesel particulate filter（DPF） is a cost-effective measure to quickly and efficiently reduce particulate matter emissions. This study experimentally analyzes real-world performance o...Retrofitting older vehicles with diesel particulate filter（DPF） is a cost-effective measure to quickly and efficiently reduce particulate matter emissions. This study experimentally analyzes real-world performance of buses retrofitted with CRT DPFs. 18 in-use Euro III technology urban and intercity buses were investigated for a period of 12 months. The influence of the DPF and of the vehicle natural aging on buses fuel economy are analyzed and discussed. While the effect of natural deterioration is about 1.2%–1.3%, DPF contribution to fuel economy penalty is found to be 0.6% to 1.8%, depending on the bus type. DPF filtration efficiency is analyzed throughout the study and found to be in average 96% in the size range of 23–560 nm. Four different load and non-load engine operating modes are investigated on their appropriateness for roadworthiness tests. High idle is found to be the most suitable regime for PN diagnostics considering particle number filtration efficiency.展开更多
How to predict the bus arrival time accurately is a crucial problem to be solved in Internet of Vehicle. Existed methods cannot solve the problem effectively for ignoring the traffic delay jitter. In this paper,a thre...How to predict the bus arrival time accurately is a crucial problem to be solved in Internet of Vehicle. Existed methods cannot solve the problem effectively for ignoring the traffic delay jitter. In this paper,a three-stage mixed model is proposed for bus arrival time prediction. The first stage is pattern training. In this stage,the traffic delay jitter patterns(TDJP)are mined by K nearest neighbor and K-means in the historical traffic time data. The second stage is the single-step prediction,which is based on real-time adjusted Kalman filter with a modification of historical TDJP. In the third stage,as the influence of historical law is increasing in long distance prediction,we combine the single-step prediction dynamically with Markov historical transfer model to conduct the multi-step prediction. The experimental results show that the proposed single-step prediction model performs better in accuracy and efficiency than short-term traffic flow prediction and dynamic Kalman filter. The multi-step prediction provides a higher level veracity and reliability in travel time forecasting than short-term traffic flow and historical traffic pattern prediction models.展开更多
The school bus routing problem(SBRP)is a central issue in transportation planning and optimization systems.SBRP seeks to plan an efficient schedule for a fleet of school buses where each bus picks up students from var...The school bus routing problem(SBRP)is a central issue in transportation planning and optimization systems.SBRP seeks to plan an efficient schedule for a fleet of school buses where each bus picks up students from various bus stops and delivers them to their designated schools while satisfying various constraints such as the maximum capacity of a bus,and the time window of a school.Due to its inherent complexity,many heuristics have been proposed to solve this combinatorial problem in an effective way.In this paper,a novel geographic information systems(GIS)-based decisionmaking framework that combines GIS,clustering techniques,network cutting techniques,and a hybrid ant colony optimization metaheuristic with the iterated Lin–Kernighan local improvement heuristic is proposed for solving the SBRP as a split delivery vehicle routing problem(SDVRP).Experiments were conducted for evaluating the proposed framework by comparing the results for solving 11 routing problems using both the proposed decision-making framework and Arc-GIS 9.2 Network Analyst which uses the greedy Dijkstra’s algorithm.The reported results of the proposed framework generally outperform that of the ArcGIS Network Analyst.In addition,the proposed decision-making framework was applied to solve a real life SBRP to demonstrate its application.展开更多
Bus rapid transit (BRT) systems have been implemented in many cities over the past two decades. Widespread adoption of General Transit Feed Specification (GTFS), the deployment of high-fidelity bus GPS data tracking, ...Bus rapid transit (BRT) systems have been implemented in many cities over the past two decades. Widespread adoption of General Transit Feed Specification (GTFS), the deployment of high-fidelity bus GPS data tracking, and anonymized high-fidelity connected vehicle data from private vehicles have provided new opportunities for performance measures that can be used by both transit agencies and traffic signal system operators. This paper describes the use of trajectory-based data to develop performance measures for a BRT system in Indianapolis, Indiana. Over 3 million data records during the 3-month period between March and May 2022 are analyzed to develop visualizations and performance metrics. A methodology to estimate the average delay and schedule adherence is presented along a route comprised of 74 signals and 28 bus stations. Additionally, this research demonstrates how these performance measures can be used to evaluate dedicated and non-dedicated bus lanes with general traffic. Travel times and reliability of buses are compared with nearly 30 million private vehicle trips. Results show that median travel time for buses on dedicated bi-directional lanes is within one minute of general traffic and during peak periods the buses are often faster. Schedule adherence was observed to be more challenging, with approximately 3% of buses arriving within 1 minute on average during the 5AM hour and 5% of buses arriving 6 - 9 minutes late during the 5PM hour. The framework and performance measures presented in this research provide agencies and transportation professionals with tools to identify opportunities for adjustments and to justify investment decisions.展开更多
Based on the symmetric two-lane Nagel–Schreckenberg（STNS） model, a three-lane cellular automaton model between two intersections containing a bus stop with left-turning buses is established in which model the occur...Based on the symmetric two-lane Nagel–Schreckenberg（STNS） model, a three-lane cellular automaton model between two intersections containing a bus stop with left-turning buses is established in which model the occurrences of vehicle accidents are taken into account. The characteristics of traffic flows with different ratios of left-turn lines are discussed via the simulation experiments. The results indicate that the left-turn lines have more negative effects on capacity,accident rate as well as delay if the stop is located close to the intersections, where the negative effect in a near-side stop is more severe than that in a far-side one. The range of appropriate position for a bus stop without the bottleneck effect becomes more and more narrow with the increase of the ratio of left-turn bus lines. When the inflow is small, a short signal cycle and a reasonable offset are beneficial. When the inflow reaches or exceeds the capacity, a longer signal cycle is helpful. But if the stop position is inappropriate, the increase of cycle fails in reducing the negative effect of left-turning buses and the effectiveness of offset is weakened.展开更多
The regulated gaseous emissions from 2 China-V compressed natural gas(CNG)buses and 2 China-V diesel buses were investigated using a portable emissions measurement system(PEMS)under real road driving conditions.Compar...The regulated gaseous emissions from 2 China-V compressed natural gas(CNG)buses and 2 China-V diesel buses were investigated using a portable emissions measurement system(PEMS)under real road driving conditions.Compared to diesel buses,CNG buses emit less NOx pollutants,but more HC and CO pollutants based on the test results obtained in this paper.In order to evaluate the pollutant emission status of CNG buses in Beijing,an instantaneous emission model as a function of vehicle speed and vehicle specific power(VSP)was developed and validated based on emission data taken from one CNG bus.The input of the instantaneous emission model consists of driving cycle,vehicle parameters,road conditions,ambient conditions and accessory use,all of which were used to calculate the instantaneous vehicle specific power(VSP).For the core model,a group of pollutant emission maps represented as functions of vehicle speed and VSP were used to calculate the second by second emission rates.Finally,the instantaneous emission rates,emission factors and fuel consumption over the selected driving cycle could be obtained as the model outputs.The predicted results for the emissions and fuel consumption of the CNG bus were very close to the tested emission data.The prediction errors for emission factors and fuel consumption varied in the range of-1.6 2%to-5.8%.展开更多
In order to reduce the load rate of CAN bus and improve the real-time performance of control system, CAN bus control system of a pure electric vehicle is studied. Communication messages of each node are optimized and ...In order to reduce the load rate of CAN bus and improve the real-time performance of control system, CAN bus control system of a pure electric vehicle is studied. Communication messages of each node are optimized and redefined by sorting the message into three types： control message, status message and alann message. Event triggered mode is added to the communication way of CAN bus, and the communication control strategy of the vehicle is made. It is proved that CAN bus load rate of control system is reduced after optimization, and the real-time performance of communication is improved effectively.展开更多
Hybrid-electric school buses became available in the US through a national consortium designed to bring hybrid-electric school buses to market by creating enough demand among school districts to encourage manufacturer...Hybrid-electric school buses became available in the US through a national consortium designed to bring hybrid-electric school buses to market by creating enough demand among school districts to encourage manufacturers to invest in development of the technology. A number of school districts in the US joined the HESB project to purchase plug-in hybrid-electric school buses. Sixteen hybrid-electric school buses were purchased and piloted in 11 states. Two of the hybrid-electric school buses were purchased by the Nevada and Sigourney school districts in the state of Iowa, US. In-use fuel economy and electricity operating costs were monitored for the two Iowa hybrid school buses and two control buses (one in each district). Fuel consumption and other operational metrics were calculated and compared for each school district. The hybrid buses were deployed in January 2008 and data were recorded through May 2010. Valuation of the data indicated that the Nevada HESB had 29.6% better fuel economy than the control bus and the Sigourney HESB had 39.2% better fuel economy than the control bus. Electrical costs per mile were also calculated for the two hybrid-electric school buses. Total operating costs per mile were calculated based on fuel use per mile for all buses and electrical costs for the hybrid-electric school buses. The cost to operate the hybrid bus in Nevada was 37 cents/mile while the control bus cost 42 cents/mile, making the hybrid bus 13% less expensive to operate. The hybrid bus in Sigourney was 27 cents/mile while the control bus was 34 cents/mile, making the hybrid bus 21% less expensive to operate. All values are in US dollars.展开更多
Currently, Brazilian buses are divided in three categories： city buses, intercity buses and coaches. That categorization results from the understanding that citizens only need to move around urban perimeters. However...Currently, Brazilian buses are divided in three categories： city buses, intercity buses and coaches. That categorization results from the understanding that citizens only need to move around urban perimeters. However, the current bus models available do not fully meet legal demands or cater for all of society＇s demands. Rural workers and students that live in rural areas also must be conveyed in buses and minibuses. Municipal and state directives prohibit employers to convey them in improper vehicles, such as trucks. Social demands, on the other hand, can be i[llustrated by federal and state programs that provide vehicles to transport students who dwell in rural settings. Accordingly, this paper proposes a new categorization of bus models available in the Brazilian market, which should account for the unique local operating conditions rural buses face, instead of only considering the type of service they provide. Further, a purpose-built vehicle is suggested i[n order to cater for the needs of rural workers and students. Rural students represent, in average, five million rural school bus riders.展开更多
The main objective of this study is the search for methods of verification of bus rollover finite element simulation which can replace a full-scale verification rollover test using single bus section. An overview of t...The main objective of this study is the search for methods of verification of bus rollover finite element simulation which can replace a full-scale verification rollover test using single bus section. An overview of the main verification methods of the computer simulation results of bus rollover is provided in the article. A bus section rollover test is conducted. A comparison between calculation and experiment results is performed. Features of bus section motion, which affect the construction deformation value, are analyzed on the basis of received good convergence between calculation and test results. The mathematical model of planar motion of the bus section until impact with ditch surface is given. This model can be used to verify values of the center of gravity velocities and accelerations of the bus section, obtained as a result of an FE （finite element） simulation.展开更多
As university campuses look to decrease their greenhouse gas emissions, plug-in electric buses may provide a low carbon alternative to conventionally fossil-powered buses. This study investigates the viability for Uni...As university campuses look to decrease their greenhouse gas emissions, plug-in electric buses may provide a low carbon alternative to conventionally fossil-powered buses. This study investigates the viability for Unitrans, the bus service for the greater Davis area and the university campus, to replace current compressed natural gas buses with plug-in electric versions. This study presents an inventory of market available electric buses, their associated costs, incentives, and infrastructure concerns, and compares projected energy use, net present cost, and greenhouse gas emissions with their CNG counterparts. ADVISOR vehicle simulation software is used to estimate the energy use of a typical electric bus (New Flyer Xcelsior XE40 300 kW) and compare to the current CNG model (Orion V) along an actual Unitrans route. The model estimates that the selected bus can travel 146 miles on a single charge, with a fuel economy of 1.75 kWh per mile, which meets the service requirements. Results for bus replacement schedules between 5 and 49 in the 12-year analysis period indicate that between 1600 and 22,000 MT of carbon can be avoided. The net present cost analysis indicates that the potential savings from the replacement of a single CNG bus with an electric bus (with available incentives) ranges from $146,000 - $211,000 per bus over its lifetime, depending on infrastructure costs.展开更多
Transit electrification has emerged as an unstoppable force,driven by the considerable environmental benefits it offers.However,the adoption of battery electric buses is still impeded by their limited flexibility,a co...Transit electrification has emerged as an unstoppable force,driven by the considerable environmental benefits it offers.However,the adoption of battery electric buses is still impeded by their limited flexibility,a constraint that necessitates adjustments to current bus scheduling plans.Consequently,this study aspires to offer a thorough review of articles focused on battery electric bus scheduling.Moreover,we provide a comprehensive review of 42 papers on electric bus scheduling and related studies,with a focus on the most recent developments and trends in this research domain.Despite this extensive review,our findings reveal a paucity of research that takes into account the robustness of electric bus scheduling.Furthermore,we highlight the critical areas of considering diverse charging modes in electric bus scheduling and integrated planning of electric buses,which have not been adequately explored but hold the potential to greatly boost the effectiveness of electric bus systems.Through this synthesis,we hope that readers could acquire a thorough comprehension of the studies in this field and be motivated to address the identified research gaps,thus propelling the progress of transit electrification.展开更多
基金The Soft Science Research Project of Ministry of Housing and Urban-Rural Development of China (No. 2008-k5-14)
文摘In order to provide important parameters for schedule designing, decision-making bases for transit operation management and references for passengers traveling by bus, bus transit travel time reliability is analyzed and evaluated based on automatic vehicle location （AVL） data. Based on the statistical analysis of the bus transit travel time, six indices including the coefficient of variance, the width of travel time distribution, the mean commercial speed, the congestion frequency, the planning time index and the buffer time index are proposed. Moreover, a framework for evaluating bus transit travel time reliability is constructed. Finally, a case study on a certain bus route in Suzhou is conducted. Results show that the proposed evaluation index system is simple and intuitive, and it can effectively reflect the efficiency and stability of bus operations. And a distinguishing feature of bus transit travel time reliability is the temporal pattern. It varies across different time periods.
基金Electric Automobile and Intelligent Connected Automobile Industry Innovation Project of Anhui Province of China(Grant No.JAC2019022505)Key Research and Development Projects in Shandong Province of China(Grant No.2019TSLH701).
文摘Proper braking force distribution strategies can improve both stability and economy performance of hybrid electric vehicles,which is prominently proved by many studies.To achieve better dynamic stable performance and higher energy recovery efficiency,an effective braking control strategy for hybrid electric buses(HEB)based on vehicle mass and road slope estimation is proposed in this paper.Firstly,the road slope and the vehicle mass are estimated by a hybrid algorithm of extended Kalman filter(EKF)and recursive least square(RLS).Secondly,the total braking torque of HEB is calculated by the sliding mode controller(SMC),which uses the information of brake intensity,whole vehicle mass,and road slope.Finally,comprehensively considering driver’s braking intention and regulations of the Economic Commission for Europe(ECE),the optimal proportional relationship between regenerative braking and pneumatic braking is obtained.Furthermore,related simulations and experiments are carried out on the hardware-in-the-loop test bench.Results show that the proposed strategy can effectively improve the braking performance and increase the recovered energy through precise control of the braking torque.
基金supported by the National Natural Science Foundation of China(71871075,91846301,71501053)China Postdoctoral Science Foundation(2015M570297)International Postdoctoral Exchange Fellowship(20160076)of China Postdoctoral Council,and CCF-DiDi Big Data Joint Lab.
文摘Improving bus travel time reliability can attract more commuters to use bus transit,and therefore reduces the share of cars and alleviates trafc congestion.This paper formulates a new bus travel time reliability metric that jointly considers two stochastic processes:the in-stop waiting process and in-vehicle travel time process,and the bus travel time reliability function is calculated by the convolution of independent events’probabilities.The new reliability metric is defned as the probability when bus travel time is less than a certain threshold and can be used in both conditions with and without bus transfer.Next,Automatic Vehicle Location(AVL)data of the city of Harbin is used to demonstrate the applicability of the proposed method.Results show that factors such as weather,day of the week,departure time,travel distance,and the distance from the boarding stop to the bus departure station can signifcantly afect the travel time reliability.Then,a case with low bus departure frequency is analyzed to show the impact of travelers’arrival distribution on their bus travel time reliability.Further,it is demonstrated that the travel time reliabilities of two bus transfer schemes of the same Origin–Destination(O–D)pair can have signifcantly diferent patterns.Understanding the bus travel time reliability pattern of the alternative bus routes can help passengers to choose a more reliable bus route under diferent conditions.The proposed bus travel time reliability metric is tested to be sensitive to the efect of diferent factors and can be applied in bus route recommendation,bus service evaluation,and optimization.
文摘This paper introduces and analyzes Korea＇s NGV （natural gas vehicles） policy for soot-free bus fleet which intends to promote CNG （compressed natural gas） bus in metropolitan area for the reduction of air pollution from road sector. At the early stage, Korean goverrmaent established various supporting policy systems to encourage public transportation companies to purchase CNG buses as a means to replace diesel buses. It was evaluated as very successful with making net economic benefit of CNG bus promotion policy. During the 2nd stage, Korean government implemented CNG hybrid bus promotion policy to further reduce both air pollution and greenhouse gas. Now, a new social demand for the vehicles is zero-emission vehicles. The author asserts that current FCEV （fuel cell electric vehicle） should be considered as an alternative to zero-emission vehicles in Korea and suggests policy recommendation for the promotion of FCEV by referring the current CNG bus promotion policy in public transportation sector.
文摘It is of increasing importance to design and implement vehicle networks for transferring information between electrical control units on Hybrid Electrical Vehicle （HEV）. This paper presents a scheme of using Controller Area Network （CAN） technology to realize communication and datasharing between the electrical units on the HEV. The principle and communication protocol of Electrical Control Units （ECU） CAN node are introduced. By considering different sensitivity of the devices to the latency of data transportation, a new design procedure is proposed for the purpose of simplifying network codes and wiring harness, reducing assembly space and weight, improving assembly efficiency, and enhancing fault-diagnose in auto networks.
文摘Based on the development demand of electric vehicles, this paper studies the communication network in electric vehicles based on CAN bus after analyzing the LCD (liquid crystal display) in electric vehicles and the status quo of research and development trend about communication network. This system uses TMS320LF2407 DSP as the controller of the control system about central signals. It has also developed the LCD system based on CAN bus and the experiment platform which is applied pure electric vehicles.
文摘Hanoi’s rapid urbanization has led to a surge in private vehicle ownership, particularly motorcycles, amidst inadequate public transportation infrastructure. Despite government efforts, many still prefer motorized transport, citing mobility and safety concerns, exacerbated by insufficient pedestrian infrastructure. This study examines the motivations behind this reliance on motorized vehicles, particularly motorcycles, in Hanoi. Findings reveal safety and convenience as primary factors driving motorized transport use, especially for accessing bus stations. Economic incentives could promote non-motorized travel and public transport adoption. Policy implications highlight the importance of addressing economic factors and improving access infrastructure to manage motorized vehicle reliance and foster sustainable urban mobility in Hanoi.
基金Supported by National Natural Science Foundation of China(Grant No.51775269)
文摘Vehicle rollover, and its resulting fatalities, is an actively researched topic especially for multi-axle vehicles in the field of vehicle dynamics and control. This paper first presents a new rollover index for a triaxle bus to accurately evaluate its rollover possibility and then discusses the influence laws of the vehicle rollover dynamics to explore the mechanism of its stability. First, a six degree of freedom rollover model of the triaxle bus is developed, including lateral, yaw, roll motion of the sprung mass of the front/rear axle, and roll motion of the unsprung mass of the front/rear axle. Next, some key parameters of the vehicle rollover model are identified. A new rollover index is deduced according to the basics of vehicle dynamics, to predict vehicle rollover risk for the triaxle bus, which is verified by TruckSim. Furthermore, the influence laws of vehicle rollover dynamics by vehicle parameters and road parameters are discussed based on the simulation results. More importantly, the results show that the new method of modeling can precisely describe the rollover dynamics of the studied bus, and the proposed new index can e ectively evaluate the rollover possibility. Therefore, this study provides a theoretical basis to improve anti-rollover ability for triaxle buses.
基金financially supported by Egged Israel Transport Cooperative Society Ltd.
文摘Retrofitting older vehicles with diesel particulate filter（DPF） is a cost-effective measure to quickly and efficiently reduce particulate matter emissions. This study experimentally analyzes real-world performance of buses retrofitted with CRT DPFs. 18 in-use Euro III technology urban and intercity buses were investigated for a period of 12 months. The influence of the DPF and of the vehicle natural aging on buses fuel economy are analyzed and discussed. While the effect of natural deterioration is about 1.2%–1.3%, DPF contribution to fuel economy penalty is found to be 0.6% to 1.8%, depending on the bus type. DPF filtration efficiency is analyzed throughout the study and found to be in average 96% in the size range of 23–560 nm. Four different load and non-load engine operating modes are investigated on their appropriateness for roadworthiness tests. High idle is found to be the most suitable regime for PN diagnostics considering particle number filtration efficiency.
基金National Science and Technology Major Project(2016ZX03001025-003)Special Found for Beijing Common Construction Project
文摘How to predict the bus arrival time accurately is a crucial problem to be solved in Internet of Vehicle. Existed methods cannot solve the problem effectively for ignoring the traffic delay jitter. In this paper,a three-stage mixed model is proposed for bus arrival time prediction. The first stage is pattern training. In this stage,the traffic delay jitter patterns(TDJP)are mined by K nearest neighbor and K-means in the historical traffic time data. The second stage is the single-step prediction,which is based on real-time adjusted Kalman filter with a modification of historical TDJP. In the third stage,as the influence of historical law is increasing in long distance prediction,we combine the single-step prediction dynamically with Markov historical transfer model to conduct the multi-step prediction. The experimental results show that the proposed single-step prediction model performs better in accuracy and efficiency than short-term traffic flow prediction and dynamic Kalman filter. The multi-step prediction provides a higher level veracity and reliability in travel time forecasting than short-term traffic flow and historical traffic pattern prediction models.
文摘The school bus routing problem(SBRP)is a central issue in transportation planning and optimization systems.SBRP seeks to plan an efficient schedule for a fleet of school buses where each bus picks up students from various bus stops and delivers them to their designated schools while satisfying various constraints such as the maximum capacity of a bus,and the time window of a school.Due to its inherent complexity,many heuristics have been proposed to solve this combinatorial problem in an effective way.In this paper,a novel geographic information systems(GIS)-based decisionmaking framework that combines GIS,clustering techniques,network cutting techniques,and a hybrid ant colony optimization metaheuristic with the iterated Lin–Kernighan local improvement heuristic is proposed for solving the SBRP as a split delivery vehicle routing problem(SDVRP).Experiments were conducted for evaluating the proposed framework by comparing the results for solving 11 routing problems using both the proposed decision-making framework and Arc-GIS 9.2 Network Analyst which uses the greedy Dijkstra’s algorithm.The reported results of the proposed framework generally outperform that of the ArcGIS Network Analyst.In addition,the proposed decision-making framework was applied to solve a real life SBRP to demonstrate its application.
文摘Bus rapid transit (BRT) systems have been implemented in many cities over the past two decades. Widespread adoption of General Transit Feed Specification (GTFS), the deployment of high-fidelity bus GPS data tracking, and anonymized high-fidelity connected vehicle data from private vehicles have provided new opportunities for performance measures that can be used by both transit agencies and traffic signal system operators. This paper describes the use of trajectory-based data to develop performance measures for a BRT system in Indianapolis, Indiana. Over 3 million data records during the 3-month period between March and May 2022 are analyzed to develop visualizations and performance metrics. A methodology to estimate the average delay and schedule adherence is presented along a route comprised of 74 signals and 28 bus stations. Additionally, this research demonstrates how these performance measures can be used to evaluate dedicated and non-dedicated bus lanes with general traffic. Travel times and reliability of buses are compared with nearly 30 million private vehicle trips. Results show that median travel time for buses on dedicated bi-directional lanes is within one minute of general traffic and during peak periods the buses are often faster. Schedule adherence was observed to be more challenging, with approximately 3% of buses arriving within 1 minute on average during the 5AM hour and 5% of buses arriving 6 - 9 minutes late during the 5PM hour. The framework and performance measures presented in this research provide agencies and transportation professionals with tools to identify opportunities for adjustments and to justify investment decisions.
基金supported by the National Natural Science Foundation of China(Grant No.50478088)the Natural Science Foundation of Hebei Province,China(Grant No.E2015202266)
文摘Based on the symmetric two-lane Nagel–Schreckenberg（STNS） model, a three-lane cellular automaton model between two intersections containing a bus stop with left-turning buses is established in which model the occurrences of vehicle accidents are taken into account. The characteristics of traffic flows with different ratios of left-turn lines are discussed via the simulation experiments. The results indicate that the left-turn lines have more negative effects on capacity,accident rate as well as delay if the stop is located close to the intersections, where the negative effect in a near-side stop is more severe than that in a far-side one. The range of appropriate position for a bus stop without the bottleneck effect becomes more and more narrow with the increase of the ratio of left-turn bus lines. When the inflow is small, a short signal cycle and a reasonable offset are beneficial. When the inflow reaches or exceeds the capacity, a longer signal cycle is helpful. But if the stop position is inappropriate, the increase of cycle fails in reducing the negative effect of left-turning buses and the effectiveness of offset is weakened.
基金Supported by the National Key Research and Development Plan(2016YFC0208005)the National Natural Science Foundation of China(51576016)
文摘The regulated gaseous emissions from 2 China-V compressed natural gas(CNG)buses and 2 China-V diesel buses were investigated using a portable emissions measurement system(PEMS)under real road driving conditions.Compared to diesel buses,CNG buses emit less NOx pollutants,but more HC and CO pollutants based on the test results obtained in this paper.In order to evaluate the pollutant emission status of CNG buses in Beijing,an instantaneous emission model as a function of vehicle speed and vehicle specific power(VSP)was developed and validated based on emission data taken from one CNG bus.The input of the instantaneous emission model consists of driving cycle,vehicle parameters,road conditions,ambient conditions and accessory use,all of which were used to calculate the instantaneous vehicle specific power(VSP).For the core model,a group of pollutant emission maps represented as functions of vehicle speed and VSP were used to calculate the second by second emission rates.Finally,the instantaneous emission rates,emission factors and fuel consumption over the selected driving cycle could be obtained as the model outputs.The predicted results for the emissions and fuel consumption of the CNG bus were very close to the tested emission data.The prediction errors for emission factors and fuel consumption varied in the range of-1.6 2%to-5.8%.
文摘In order to reduce the load rate of CAN bus and improve the real-time performance of control system, CAN bus control system of a pure electric vehicle is studied. Communication messages of each node are optimized and redefined by sorting the message into three types： control message, status message and alann message. Event triggered mode is added to the communication way of CAN bus, and the communication control strategy of the vehicle is made. It is proved that CAN bus load rate of control system is reduced after optimization, and the real-time performance of communication is improved effectively.
文摘Hybrid-electric school buses became available in the US through a national consortium designed to bring hybrid-electric school buses to market by creating enough demand among school districts to encourage manufacturers to invest in development of the technology. A number of school districts in the US joined the HESB project to purchase plug-in hybrid-electric school buses. Sixteen hybrid-electric school buses were purchased and piloted in 11 states. Two of the hybrid-electric school buses were purchased by the Nevada and Sigourney school districts in the state of Iowa, US. In-use fuel economy and electricity operating costs were monitored for the two Iowa hybrid school buses and two control buses (one in each district). Fuel consumption and other operational metrics were calculated and compared for each school district. The hybrid buses were deployed in January 2008 and data were recorded through May 2010. Valuation of the data indicated that the Nevada HESB had 29.6% better fuel economy than the control bus and the Sigourney HESB had 39.2% better fuel economy than the control bus. Electrical costs per mile were also calculated for the two hybrid-electric school buses. Total operating costs per mile were calculated based on fuel use per mile for all buses and electrical costs for the hybrid-electric school buses. The cost to operate the hybrid bus in Nevada was 37 cents/mile while the control bus cost 42 cents/mile, making the hybrid bus 13% less expensive to operate. The hybrid bus in Sigourney was 27 cents/mile while the control bus was 34 cents/mile, making the hybrid bus 21% less expensive to operate. All values are in US dollars.
文摘Currently, Brazilian buses are divided in three categories： city buses, intercity buses and coaches. That categorization results from the understanding that citizens only need to move around urban perimeters. However, the current bus models available do not fully meet legal demands or cater for all of society＇s demands. Rural workers and students that live in rural areas also must be conveyed in buses and minibuses. Municipal and state directives prohibit employers to convey them in improper vehicles, such as trucks. Social demands, on the other hand, can be i[llustrated by federal and state programs that provide vehicles to transport students who dwell in rural settings. Accordingly, this paper proposes a new categorization of bus models available in the Brazilian market, which should account for the unique local operating conditions rural buses face, instead of only considering the type of service they provide. Further, a purpose-built vehicle is suggested i[n order to cater for the needs of rural workers and students. Rural students represent, in average, five million rural school bus riders.
文摘The main objective of this study is the search for methods of verification of bus rollover finite element simulation which can replace a full-scale verification rollover test using single bus section. An overview of the main verification methods of the computer simulation results of bus rollover is provided in the article. A bus section rollover test is conducted. A comparison between calculation and experiment results is performed. Features of bus section motion, which affect the construction deformation value, are analyzed on the basis of received good convergence between calculation and test results. The mathematical model of planar motion of the bus section until impact with ditch surface is given. This model can be used to verify values of the center of gravity velocities and accelerations of the bus section, obtained as a result of an FE （finite element） simulation.
文摘As university campuses look to decrease their greenhouse gas emissions, plug-in electric buses may provide a low carbon alternative to conventionally fossil-powered buses. This study investigates the viability for Unitrans, the bus service for the greater Davis area and the university campus, to replace current compressed natural gas buses with plug-in electric versions. This study presents an inventory of market available electric buses, their associated costs, incentives, and infrastructure concerns, and compares projected energy use, net present cost, and greenhouse gas emissions with their CNG counterparts. ADVISOR vehicle simulation software is used to estimate the energy use of a typical electric bus (New Flyer Xcelsior XE40 300 kW) and compare to the current CNG model (Orion V) along an actual Unitrans route. The model estimates that the selected bus can travel 146 miles on a single charge, with a fuel economy of 1.75 kWh per mile, which meets the service requirements. Results for bus replacement schedules between 5 and 49 in the 12-year analysis period indicate that between 1600 and 22,000 MT of carbon can be avoided. The net present cost analysis indicates that the potential savings from the replacement of a single CNG bus with an electric bus (with available incentives) ranges from $146,000 - $211,000 per bus over its lifetime, depending on infrastructure costs.
基金supported by the National Natural Science Foundation of China(Nos.72101115,72371130,and 72001108)Natural Science Foundation of Jiangsu(Nos.BK20210316 and BK20200483)Fundamental Research Funds for the Central Universities(Nos.30923011016 and 30921011211).
文摘Transit electrification has emerged as an unstoppable force,driven by the considerable environmental benefits it offers.However,the adoption of battery electric buses is still impeded by their limited flexibility,a constraint that necessitates adjustments to current bus scheduling plans.Consequently,this study aspires to offer a thorough review of articles focused on battery electric bus scheduling.Moreover,we provide a comprehensive review of 42 papers on electric bus scheduling and related studies,with a focus on the most recent developments and trends in this research domain.Despite this extensive review,our findings reveal a paucity of research that takes into account the robustness of electric bus scheduling.Furthermore,we highlight the critical areas of considering diverse charging modes in electric bus scheduling and integrated planning of electric buses,which have not been adequately explored but hold the potential to greatly boost the effectiveness of electric bus systems.Through this synthesis,we hope that readers could acquire a thorough comprehension of the studies in this field and be motivated to address the identified research gaps,thus propelling the progress of transit electrification.
