Conventional Bus Research Articles

Study on Location of Bus Stop in Subway Service Area Based on Residents’ Travel Accessibility

This research aims at establishing an integrated urban public transport system with a subway route supplemented by conventional bus lines, in order to enable residents’ “door-to-door” travel. This paper first analyzed the attraction area of the subway, and then used the GIS tools to calculate and analyze residents’ accessibility to adjacent bus stops. Moreover, it created a preliminary layout of bus stops for residential areas with extremely low accessibility using an improved potential model. From the perspective of minimizing residents’ travel costs and bus stop infrastructure deployment costs, a bus stop site selection optimization model was developed. According to the characteristics of the model, the non-dominated sorting genetic algorithm II (NSGA-II) was employed to solve the optimal bus stop locations. In addition, the entropy weight technique for order of preference by similarity to ideal solution (TOPSIS) evaluation model was used to evaluate and sort candidate schemes, accordingly, and thus the optimal site selection scheme was identified. Finally, a before-after comparative analysis on residents’ travel accessibility was conducted. Results show that the proposed method can effectively improve residents’ accessibility to bus stops, which facilitates residents to transfer from conventional bus to subway. Furthermore, it provides a basis for the follow-up optimization of the connection between subway and conventional bus lines.

Optimal variable vehicle scheduling strategy for a network of electric buses with fast opportunity charging

The introduction of battery-powered electric buses (EBs) presents promising prospects for greener and more sustainable public transit. However, recharging activities of EBs to extend the total daily operation range, enabled by fast opportunity charging approach, create a significant challenge for attaining better, or equivalent, operational efficiency than conventional diesel buses. We propose a novel variable vehicle scheduling strategy of a transit EB network with multiple depots to meet this challenge by right shifting trip departure times. A numerical example is used as an expository device to illustrate the variable EB-scheduling methodology, followed by an empirical case study in the city of Dalian, China. The results show how the optimised variable EB scheduling strategy can reduce the impact of recharging activities on the operation’s efficiency. It has been found that by inserting a small schedule delay it is possible to save operational costs, especially through a reduction of the fleet size.

Evaluating the appropriate fuel-based bus technology in Indian context by integrating Fuzzy AHP-Fuzzy TOPSIS

According to WHO, India's transportation sector accounts for 11% of its CO2 emissions. Sustainable energy-based bus transportation systems are a necessity in Indian context. However, factors like capital cost, refueling infrastructure, etc. are also important as most State Road Transport Undertakings (SRTUs) are operating in severe losses. This study evaluates the most effective fuel-based bus transport system in the Indian context through the comparative analysis of electric buses, hydrogen fuel cell buses, compressed natural gas (CNG) buses, and conventional diesel buses. Multiple criteria decision making (MCDM) approach was employed through the use of Fuzzy AHP-Fuzzy TOPSIS tool. Electric buses were found to be the best alternative, and the stakeholders placed less importance on noise levels and rated the initial cost of buying a bus, tailpipe emissions, and operating costs as major determining parameters. The findings may help national and state-level decision-making agencies in planning for the future sustainable bus systems.

Modeling emission reduction benefits of the premium point-to-point bus service in Metropolitan Manila, Philippines – a scenario analysis

Road transport has been one of the largest contributors to global carbon emissions. In the Philippines, one such measure is the introduction of a relatively new public transport mode called the “Premium Point-to-Point (P2P) Bus Service”, which features shorter travel time and lower emission intensity than conventional buses. In light of the significant deficiency in transport emission studies for Philippine cities, this paper presents a scenario-based method for quantifying the potential emission reduction benefits of the P2P bus in Metropolitan Manila. Based on a pro rata mode shift assumption, it is estimated that a 1% mode shift of passengers from existing motor modes to P2P buses would lead to 0.64% reduction of total emissions over selected travel routes in Metro Manila. The analytical method addresses the acute emission data scarcity in the Philippines, and provides early evidence on the aggregate environmental benefits of P2P buses. Extensive sensitivity tests are conducted to verify the simulation results and identify key determinants of emission reduction. The tests confirm the robustness of research findings and further uncover the great potential of increasing vehicle occupancy levels to mitigate vehicle emissions in Metro Manila. Policy implications for enhancing the environmental benefits of P2P buses are provided.

Designing fast-charge urban electric bus services: An Integer Linear Programming model

Currently, there is serious political support for the decarbonization of transport locally, nationally and even internationally. Public transport operators are focusing on the use of electric buses as an opportunity to reduce greenhouse gas emissions and improve air quality. However, using electric buses requires a functional infrastructure of urban charging points. Fast-charging can be made available thanks to the progress made on the major technological charging devices in recent years. In this study, we consider an optimization problem of the design of an infrastructure for a fast-charge city electric bus service. The decisions which have to be made include determining a mixed fleet of conventional and electric buses, points for electric chargers and power stations, quantities of charging plug devices, a distribution of electric buses between the routes, and matching chargers with power stations. The objective is to maximize the route-weighted total passenger capacity of electric buses. An Integer Linear Programming model has been developed to complement the existing non-linear model. The new model is efficient if the number of possible charging spots is small, which is natural and frequent in practice. Extensive computer experiments demonstrate that our approach delivers near-optimal solutions of the studied problem in ten minutes for real-world instances on a standard PC and it outperforms the earlier approach on every instance.

Estimating CO<sub>2</sub> Emissions for Bus Rapid Transit (BRT) Using Life Cycle Assessment: A Case Study in Rio de Janeiro City

The amount of greenhouse gases has been growing dramatically in recent decades, producing global warming and causing climate change that affects the entire planet. To mitigate these emissions, several nations have committed to implementing measures to reduce emissions of these gases, with carbon dioxide being the main one. The transport sector is one of the leading carbon emitters. It needs to be the object of attention from government authorities and private companies so that sustainable solutions are planned and implemented to reduce the fossil fuel consumption. The emerging solutions point to implementing public transport in systems that use large-capacity vehicles, replacing conventional cars and buses. However, such systems require constructing a complex infrastructure, which will also produce emissions. Thus, it is necessary to balance the emissions produced by the new system with the emissions avoided by replacing the old system, for a clear quantification of the carbon reduction. This balance is best accomplished using the system lifecycle assessment approach. This case study presents the life cycle assessment, according to ISO 14040 standards, of the BRT system implemented in Rio de Janeiro, Brazil based on real data collected during the construction of the system. The results show that the system will take 16 years to compensate for the emissions produced, and in the life cycle, the projected reduction is about half a million tons of CO<sub>2</sub>. The study indicates a path that can be useful to planners seeking to reduce carbon in the public transport sector.

Investigation of basic operating characteristics of conventional, diesel-electric and hybrid-electric city buses under urban driving conditions

Basic operating characteristics of Conventional, Diesel-Electric (DE) and Hybrid-Electric (HE) city buses were investigated under real-world driving conditions. To perform the investigation, real-time operating data of the buses were collected on Campus-Return route of Sakarya, Turkiye. It was observed that although traction power versus bus speed characteristics indicated similarities for the buses, the engine power versus bus speed characteristics did not indicate the same similarities. The main difference was that while the engine powers of the Conventional and DE buses increased steeply to their maximum during sudden accelerations, that of the HE bus increased gradually to its maximum. While the traction and braking energy traces of the buses were quite similar, the engine energy traces of the HE bus was significantly different although the buses were driven on the same route.

下车信息对公交乘客精细化分类影响研究

The widely used bus one ticket system lacks off boarding information, and the passenger classification based on the dataset of one-ticket bus system needs to be refined to evaluate the classification effect. This study uses the large-scale bus ticket data with alighting information to compare and analyze the transit rider classification models with and without the alighting information to explore the impact of the missing alighting information on the fine classification of transit riders. The classification indexes and combined clustering method are adopted to refine the classification of bus passengers. A case study of Beijing conventional buses which contain boarding and alighting data of 28 consecutive days is presented and used to analyze the impact of bus alighting data and classification indexes on the transit rider classification results. The result indicates that both models successfully complete the fine classification of the riders and reflect the spatio-temporal characteristics of each type of riders. The model with alighting information is able to identify the distance-concerned type with few samples such as the long-distance transit riders accounting for 0.25%. The standard deviation of the average proportion of categories in the model without alighting information is much smaller than that in the model with alighting information. The results obtained from the model without alighting information are more balanced, and the regularity of various categories of passengers in multiple dimensions is significantly different, which can better reflect the macro characteristics of classification.

Energy Demand Model of Battery E-Buses for LPT: Implementation, Validation and Scheduling Optimization

The progressive conversion of conventional bus fleets into full-electric fleets have gained focus in recent years, instilled by awareness about the environment and significant trends of urbanization. Public transport operators in major cities worldwide have put efforts into fulfilling this change. However, an efficient electrification process is still a challenge for most operators. This paper aims to propose an E-Bus vehicle model that estimates the actual energy consumption. The proposed model is implemented on the case study of a real bus line for Local Public Transport (LPT) and considers all technical characteristics of the vehicle. Real-time input data are represented by real driving cycles of the actual bus fleet and slope profile of the line. Real-time input data allow to establish directly the influence on the energy consumed during real operations. As simulation results, the global energy consumption and battery State of Charge (SOC) are then computed for the whole daily service operations. The simulation results are validated with the real data available and several scenarios are then considered within the simulations. Based on the results obtained, further improvements are proposed and discussed aiming to optimize the utilization of bus fleet, regarding both vehicles scheduling and new charging solutions.

Fast Bus Voltage Control of Single-Phase Grid-Connected Converter With Unified Harmonic Mitigation

This paper presents a comprehensive analysis of the harmonic sources of the single-phase grid-connected voltage source converter (VSC), which leads to an alternative approach for DC bus voltage control of the VSC under grid voltage distortion with a significant switching dead time. A selective current harmonic controller with the zero-reference structure plays a vital role in rejecting the harmonic components in the grid reference current created by the bus voltage control loop and the harmonic components in the grid voltage and in the VSC caused by the switching dead time. Therefore, the bus voltage control can adopt a conventional proportional-integral regulator tuned at a fast bandwidth. The proposed control scheme implemented in the multiple unbalanced synchronous reference frames was validated with a bidirectional 2-kVA VSC under grid voltage distortion and a significant dead time. Furthermore, the proposed control scheme exhibited the transient response and grid current quality superior to the conventional bus voltage control methods with a notch filter and a low-pass filter. The proposed control scheme has inherent frequency adaption.

Analysing the acceptance of autonomous buses in real-life traffic environments: pilot project with tourists in Malaga, Spain

ABSTRACT Despite the significant technological progress with Autonomous Buses (ABs), there is still a limited understanding how users perceive and experience large, mass transit ABs in real-life traffic environments. This paper follows a pilot project on AB use by tourists in the city of Malaga, Spain. Discrete choice analysis was employed to study their willingness to use the AB and the passengers’ actual satisfaction on board the AB. The obtained results reveal higher willingness levels to adopt ABs among individuals more open to new technologies and more environmentally conscious. Higher levels of satisfaction on board are reported by older passengers, women, employed, private vehicle users, and people with environmental consciousness and openness to new technologies. Finally, the research discusses how socio-demographics and personality-related barriers affect the further implementation of autonomous mobility in public transportation systems, adding new reflections on the capacity of ABs to support or even replace conventional buses.

Optimal selection of vehicle types for an electric bus route with shifting departure times

Transition to electrified transit vehicles has attracted a great public attention to achieve a greener public transport service. This work develops a methodology for multi-type electric buses (EBs) accommodating spatio-temporally imbalanced passenger demand to improve significantly the operating efficiency. However, a new complexity of this multi-type EB scheme in contrast to conventional diesel buses occurs because multi-type EBs are characterized by different capacities, limited driving ranges, decisions on recharging time and/or locations and high initial investment costs. This work proposes a new, integrated timetabling and vehicle scheduling problem with shifting departure time to attain an even-load timetable using different types of EBs at a route’s max-load stop, considering the use of fast/opportunity charging strategy. A genetic algorithm associated with right shifting of departure time has been developed to solve the resulting formulation, which is shown to be an NP-hard problem. A numerical example is used to illustrate the developed methodology, and a case study based on a scenario in the city of Dandong, China shows that the scheme of combining multiple vehicle types for a bus route not only can reduce the total cost but also bring out greater benefits than the single vehicle-type operation. From the operator viewpoint, it reduces passenger load surplus cost by approximately 11.2% for small Type A and 14.8% for large Type B. Moreover, the value of leftover pax unit cost has a significant effect on the selection of vehicle types, but has little effect on the number of trips or departures. This work shows that the higher the leftover pax unit cost is, the higher the number of large vehicle types is.

A review on technological aspects of different PWM techniques and its comparison based on different performance parameters

AbstractUse of Pulse Width Modulation (PWM) techniques has enabled the converters to be used in low‐frequency high‐power applications. The main objectives of PWM are to reduce the line current harmonic, switching energy loss, and torque pulsation and motor acoustic noise (for motor drive applications). This paper mainly deals with selective harmonic elimination PWM (SHEPWM), Hysteresis current controlled PWM (HCPWM), space vector PWM (SVPWM), bus‐clamping PWM (BCPWM), and the most advanced wavelet PWM technique (WPWM). Different conventional as well as advanced soft computing techniques have been discussed for SHEPWM in order to solve the complex non‐linear transcendental equations and obtain the optimized switching angles. The paper also deals with different conventional and advanced bus clamping sequences that have shown superior result in mitigating the switching loss. In order to judge the true performance of SHEPWM and CSVPWM in terms of accuracy of obtaining the switching angles, convergence rate, THD, torque ripple, switching energy loss, etc., a common experimental test bench consisting of three‐phase, two‐level, six switch inverter coupled with a 2 hp, 50 Hz, three‐phase induction machine has been formed. The selected BIA‐based SHEPWM and CSVPWM have been implemented in the MATLAB simulation software, and the same has also been applied to the experimental test bench through dSPACE 1104 DAC card. Performance of HCPWM and different BC‐PWM sequences has also been verified using the same experimental test bench. This manuscript will help the researches and practitioners working in this field, to gain a clear idea about the type of PWM to be used for their specific application in order to achieve superior performance.

Perception of safety in Public Transport in Brazil

This current study examines the perception of safety on the public bus transit system in a large Brazilian metropolis. Using a web-based survey, the study reached a convenient sample of bus users of a local university who were victims and witnesses to crime in two different types of local bus transit environments - the BRT MOVE - a modern bus system and its opposing counterpart - the conventional bus system. Research questions investigate whether or not riders’ perception of safety is influenced by the presence of mechanisms of control and surveillance on buses. Using a linear regression model, this study hypothesizes that the perception of safety among victims and/or witnesses to crime varies according to exposure to risk in different bus transit systems. Limitations of the results were addressed and reliability and validity issues were reviewed. This study demonstrates the relevance of different types of risk factors on riders’ perception of safety on buses, bus stops, and stations. This contributes to widening the range of public transit safety solutions in Brazil.

Application of modular vehicle technology to mitigate bus bunching

The stochastic nature of public transport systems leads to headway variability and bus bunching, causing both operator and passenger cost to increase significantly. Traditional strategies to counter bus bunching, including bus-holding, stop-skipping, and bus substitution/insertion, suffer from trade-offs and shortcomings. Autonomous modular vehicle (AMV) technology provides an additional level of flexibility in bus dispatching and operations, which can offer significant benefits in mitigating bus bunching compared to strategies available with conventional buses. This paper introduces a novel alternative to stop-skipping by leveraging the new capabilities offered by AMVs (in particular, en-route coupling and decoupling of modular units). We develop a simple bus-splitting strategy that directs a modular bus to decouple into individual units when it experiences a headway longer than a given threshold. We then use a macroscopic simulation to present a proof-of-concept evaluation of the proposed modular strategy compared to a benchmark traditional stop-skipping strategy and the base (no control) case. We find that the proposed strategy outperforms the benchmark in decreasing each of the three travel time components: waiting time, in-vehicle time, and walking time (which it eliminates completely). It therefore reduces the overhead of bus bunching and thus the travel cost by more than twice as much as the benchmark for busy bus lines. Simultaneously, it also reduces headway variability to a comparable degree. Furthermore, we analyze different control thresholds for applying the proposed strategy, and show that it is most effective when applied proactively, i.e. with the control action being triggered even by small headway deviations.

Semi-autonomous bus platooning service optimization with surrogate modeling

Autonomous driving holds great promise for easing the driver shortage issue that has occurred in many countries. In this paper, we consider a semi-autonomous transit system where (1) individual buses could form platoons to increase bus capacity during peak hours and operate separately during off-peak hours; and (2) buses may drive autonomously in certain geofenced areas yet need to be guided by human drivers elsewhere (e.g., SAE level 4, semi-autonomous). We model buses driving autonomously within the geofenced area as short-turn bus service, and jointly optimize bus dispatch headway, platoon size and service type through an integer programming model to address the driver shortage issue. The proposed model considers real-world and micro-level bus operation processes for mixed traffic of short-turn and full route buses, with bus fleet and driver workforce constraints being modeled endogenously. Since the model is non-linear, we further develop a radial basis function-based surrogate framework to solve the model efficiently. Experimental results show that, compared to the conventional bus service that uses fixed bus capacity only, semi-autonomous bus platooning service reduces operation cost significantly while reducing passenger wait time. System performance variations of the proposed model under different driver availabilities are also examined.

Comparative life cycle impact assessment of electric and conventional bus in Vietnam

Transportation is one of the key sectors causing greenhouse gas (GHG) emissions and air pollution. With the substantial increase in passenger and freight transportation, the corresponding GHG emissions and air pollutants are expected to increase significantly. Recent global and national policies are targeting at reducing environmental impacts of transportation activities. The promotion of public transportation and development of electric buses (e-buses) will reduce the use of fossil fuels in transportation, and consequently, reduce GHG emissions. This study assesses the life cycle GHG emissions and other environmental impacts of e-bus, and compares them with those of conventional bus operated in Vietnam. The results indicate that e-bus is a preferred choice in most of studied environmental impact categories over the whole life cycle such as GHG emission, ozone depletion, ozone formation, fine particulate matter formation, acidification, etc. For GHG emissions, the adoption of electric mobility will reduce 42.62 gCO2eq per passenger km of carbon footprint if conventional buses are substituted by e-buses in Vietnam.

Review of the energy forecasting and scheduling model for electric buses

Electric buses are getting more interest to be implemented in the public transport sector by different countries as a carbon mitigation strategy. However, there are a few issues with electric buses such as limited driving range and long recharging time compared to the conventional diesel bus. Due to its limited energy storage, estimation of the energy consumption for the electric buses becomes a crucial research area to prevent sufficient energy for electric buses during the service. The long recharging time of the electric buses requires a vehicle and a charging scheduling to ensure fulfilling the passenger demand without compromising the energy demand. The paper will review the state-of-the-art model for the energy forecasting model of the electric buses and electric bus charging scheduling models. The paper then compares the parameter in the energy forecasting model, the optimization objective, the charger technology, the charging pattern, and the constraint in the electric bus scheduling model. The purpose is to provide a well-structured comprehensive review on these energy forecasting and electric bus charging scheduling for engineers, researchers, investors, policy makers, bus depot companies, and other interested parties.

Characterization of battery electric transit bus energy consumption by temporal and speed variation

De-carbonizing transport is an important strategy for combating climate change and reducing the health impacts of air pollutants. The transit bus sector is one of the highest potential categories to be electrified with Battery-Electric Buses (BEBs). The energy consumption and fueling patterns of BEBs, however, will be different from conventional technology buses, so research is needed to better understand these phenomena to make the BEB rollout successful. We have analyzed the BEB activity and charging data collected over a year from a transit fleet (consisting of 40-ft and 60-ft BEBs) undergoing complete electrification. The average energy consumption for 40-ft and 60-ft buses were 2.6 ± 0.3 kWh/mile and 3.6 ± 0.5 kWh/mile, respectively, over the year. The regenerative braking recovered a significant amount of energy spent and that accounts for 37.3% and 40.2% of the total average energy required for 40-ft and 60-ft bus operation, respectively. Bus speed has a significant effect on average energy consumption per mile; the higher speed resulted in less energy consumption for both types of buses. The variability of seasonal and intra-day energy consumption per mile can be attributed to increased use of air conditioner (A/C) and heater, which were controlled according to the ambient temperatures. This transit agency may incur 16.2 ± 2.1% (based on current fleet composition, energy tariffs) more energy costs in Summer compared to Winter, if no optimized operation is used. This effort provides reliable BEB energy consumption estimates that can be used for any transit fleet's energy efficiency objective.

Electric Bus Scheduling and Timetabling, Fast Charging Infrastructure Planning, and Their Impact on the Grid: A Review

Transit agencies are increasingly embracing electric buses (EB) as an energy-efficient and emission-free alternative to the conventional bus fleets. They are rapidly replacing conventional buses with electric ones. As a result, emerging challenges of electrifying public transportation bus networks in cities should be addressed. Introducing electric buses to the bus transit system would affect the public transit operation planning steps. The steps are network design, timetabling, bus scheduling, and crew scheduling. Regarding the functional and operational differences between conventional buses and electric buses, such stages should be changed and optimized to enhance the level of service for the users while reducing operating costs for service providers. Many mathematical optimization models have been developed for conventional buses. However, such models would not fit the electric buses due to EBs’ limited traveling range and long charging time. Therefore, new mathematical models should be developed to consider the unique features of electric buses. We present a comprehensive literature review to critically review and classify the work done on these topics. This paper compares the studies that have been done in this field and highlight the missing links and gaps in the considered papers, and the potential future studies that could be done. The considered papers cover the integration of timetabling and vehicle scheduling, recharging scheduling planning, and fast charging infrastructure location planning and its impacts on the grid. The main goal of this research is to highlight the research gaps and potential directions for future studies in this domain to encourage more realistic and applicable models and solution approaches for fully electric bus transit systems.