Search Results (25)

The air quality within urban public transport is a critical determinant of passenger health. In the crowded and poorly ventilated cabins of Almaty’s metro, buses, and trolleybuses, concentrations of CO₂ and PM_2.5 often accumulate, elevating the risk of respiratory and cardiovascular diseases. This study investigates the air quality along three of the city’s busiest transport corridors, analyzing how the concentrations of CO₂, PM_2.5, and PM₁₀, as well as the temperature and relative humidity, fluctuate with the passenger density and time of day. Continuous measurements were collected using the Tynys mobile IoT device, which was bench-calibrated against a commercial reference sensor. Several machine learning models (logistic regression, decision tree, XGBoost, and random forest) were trained on synchronized environmental and occupancy data, with the XGBoost model achieving the highest predictive accuracy at 91.25%. Our analysis confirms that passenger occupancy is the primary driver of in-cabin pollution and that these machine learning models effectively capture the nonlinear relationships among environmental variables. Since the surveyed routes serve Almaty’s most densely populated districts, improving the ventilation on these lines is of immediate importance to public health. Furthermore, the high-temporal-resolution data revealed short-term pollution spikes that correspond with peak ridership, advancing the current understanding of exposure risks in transit. These findings highlight the urgent need to combine real-time monitoring with ventilation upgrades. They also demonstrate the practical value of using low-cost IoT technologies and data-driven analytics to safeguard public health in urban mobility systems. Full article

The energy transition toward greater electrification leads to incentives in public transportation fed by catenary-powered networks. In this context, emerging technological devices such as in-motion-charging vehicles and electric vehicle charging points are expected to be operated while connected to trolleybus networks as part of new electrification projects, resulting in a significant demand for power. To enable a significant increase in electric transportation without compromising technical compliance for voltage and current at grid systems, the implementation of stationary battery energy storage systems (BESSs) can be essential for new electrification projects. A key challenge for BESSs is the selection of the optimal converter topology for charging their batteries. Ideally, the chosen converter should offer the highest efficiency while minimizing size, weight, and cost. In this context, a modular dual-active-bridge converter, considering its operation as a full-power converter (FPC) and a partial-power converter (PPC) with module-shedding control, is analyzed in terms of operation efficiencies and thermal behavior. The goal is to clarify the advantages, disadvantages, challenges, and trade-offs of both power-processing techniques following future trends in the electric transportation sector. The results indicate that the PPC achieves an efficiency of 98.58% at the full load of 100 kW, which is 1.19% higher than that of FPC. Additionally, higher power density and cost effectiveness are confirmed for the PPC. Full article

Reducing greenhouse gas (GHG) emissions depends mostly on urban transport electrification. However, the role of trolleybus systems in this process is still under discussion. The objective of this study was to analyze the viability of trolleybus buses in relation to diesel buses regarding environmental and economic aspects. The research was conducted in Vilnius, Lithuania using an extended CO₂ emission methodology incorporating physicochemical fuel properties and real-world operational data that allowed us to estimate CO₂ emissions and economic impacts. The findings indicate that the Vilnius trolleybus system prevents 84,996.32 kg of CO₂ emissions monthly compared to diesel buses (gross avoided emissions). After accounting for emissions from electricity generation (based on Lithuania’s 2023 grid mix), the net avoided emissions are approximately 61,569 kg of CO₂ per month, equivalent to EUR 4284 in carbon credits. The system also significantly reduces local air pollutants. Moreover, the new In-Motion Charging (IMC) technology improves system flexibility by decreasing dependence on overhead wires and maintaining low emission levels. IMC trolleybuses represent a cost-efficient option compared to battery-electric buses (BEBs) and hydrogen fuel cell buses (FCEBs). Our findings support the European Union’s decarbonization goals and provide essential insights for policymakers considering public transportation electrification efforts. Full article

The need to assess whether accessibility in urban mobility meets the required standards to provide a satisfactory experience for users is emphasized. The general objective of this research is to evaluate pedestrian accessibility in urban mobility, taking as a case study different access points such as the sidewalks and crossings between the trolleybus system and the EFE metro system in Valparaíso. Specific objectives have been set, including identifying the area to study and the elements to evaluate, designing an evaluation system, and applying descriptive and numerical methods for the assessment. The methodology used includes two approaches: the descriptive, which provides a detailed view of accessibility conditions in each evaluated area, highlighting aspects such as physical condition and compliance with regulations, and the numerical, which assigns quantitative values to the elements being assessed to establish a classification of accessibility levels. Additionally, a survey was conducted to obtain a subjective view of pedestrian preferences. Based on the above, evaluating pedestrian accessibility in urban mobility in Valparaíso allowed for identifying aspects that require improvement to ensure a satisfactory experience for users. Furthermore, it promotes the use of both transportation systems and provides recommendations for future research. Full article

Urban public transport companies worldwide are introducing environmentally friendly bus solutions, and in cities with an existing trolleybus network, battery-assisted trolleybuses are an efficient alternative. Equipped with a traction battery, these vehicles allow a short range outside of the trolley lines and on-board recuperation, and they combine the advantages of electric buses and trolleybuses without the need for costly infrastructure expansions. Two similar battery-assisted trolleybuses are in operation in Žilina, where the unitary traction energy consumption has been observed to decrease as a function of the battery-powered and on-trolley-line vehicle run ratio. This theory was confirmed by statistical regression analysis of real operational data for one year of operation in different situations. This research also includes an analysis of battery-assisted trolleybuses’ operation on conventional trolleybus lines, which brought surprising findings, as well as an analysis of other selected indicators that can be dependent on the battery run ratio. These findings can contribute to reducing traction energy consumption by simply modifying the operating technologies without the need for extensive investment in infrastructure or vehicle equipment. This research is pilot research ready for in-depth research. Full article

The concept of green public transport in Poland is a challenge posed to Polish cities, which reflects the AFIR (Regulation for the Deployment of Alternative Fuels Infrastructure) regulation and the amended Polish Law on Electromobility and Alternative Fuels. The fulfillment of the established prerequisites requires taking steps toward the implementation of the electrification process of the fleet of bus vehicles. The goal of this process is to replace the fleet of buses equipped with internal combustion engines (conventional buses) with zero-emission buses. In the category of zero-emission vehicles, we distinguish between electric-powered buses (electric buses), hydrogen-powered buses (hydrogen buses) and trolleybuses. It is forecast that such exchanges will be spread out over time and may last 16 to 20 years. Thus, an important element in these activities is planning, which, as a process, leads to the establishment of tasks, resources and activities aimed at realizing or achieving the desired goal. It was assumed that the purpose of the article is to present the essence of planning the process of electrification of the bus fleet of vehicles in Polish cities. The content of the article refers to the concept of planning the process of electrification of the bus fleet of vehicles in urban areas, taking into account economic aspects, sources of financing and analysis of the feasibility of this process on the example of a selected Polish city. The planning process was presented using the example of a city integrated with the surrounding nature. The choice of the city is not accidental because the analyzed urban area lies in the green part of the West Pomeranian Voivodeship, in the vicinity of which there are four nature reserves. The city is situated on two lakes, which together occupy 11.2% of the city’s area, and there are also numerous green areas in the city. The green nature of the city argued for taking action to reduce local emissions of pollutants generated by public transport. The process of planning the electrification of the bus fleet was carried out based on environmental and economic aspects. In economic terms, an important element is the possibility of obtaining external financing and the analysis of the feasibility of the planned process of electrification of the bus fleet. The conducted research clearly indicated that the presented process of planning the electrification of the bus fleet in the selected urban area allows for a precise interpretation of the considered planning in environmental and economic terms. Such an interpretation is important for the evaluation process of the analyzed planning and the implementation of the concept of green public transport in Polish cities, as well as the transparency of this process to other European cities and beyond. Full article

Catenary-powered networks are expected to play a pivotal role in urban energy transition, due to the larger deployment of electric public transport, in-motion-charging (IMC) vehicles, and catenary-backed electric vehicle chargers. However, there are technical challenges that must be overcome to ensure the successful utilization of existing networks without compromising vehicle performance or compliance with network standards. This paper aims to validate the use of battery energy storage systems (BESS) built from second-life batteries as a means of retrofitting catenary-powered traction networks. The objective is to increase the network robustness without creating a negative impact on its overall operational efficiency. Consequently, more electrification projects can be implemented using the same network infrastructure without substantial modifications. Furthermore, a power management scheme is presented which allows the voltage and current range allowed in the catenary network and the BESS maximum charging rate to be controlled from user-defined values. The proposed control scheme is adept at customizing the BESS size for the specific application under consideration. Validation is performed on a case study of the trolleybus system in Bologna, Italy. Full article

As electromobility and especially the electrification of public transportation develops, it is necessary to safeguard human health and minimize environmental impact. Electromagnetic fields generated by the current flowing through on-board batteries, installations, converters, propulsion, air conditioning, heating, lighting, or wireless communication systems in these vehicles may pose risks to drivers and passengers. This research investigates electromagnetic fields induced by extreme low-frequency currents and permanent magnets on electric and trolleybuses implanted in Lublin, Poland. The identification of electromagnetic fields concerned an electric bus model and two trolleybus models. A comparative analysis of the results obtained with the permissible limits in the environment was carried out. Full article

Several cities worldwide are studying the replacement of their trolleybus systems with diesel buses or battery electric buses, due to their flexibility and lower operational costs. Diesel buses are considered a major cause of gas emissions in cities, while battery electric buses employ cutting-edge technology, but there is still discussion around the topic due to their technology costs, autonomy, and the sustainability of battery packs. In this study, we evaluated the trolleybus system’s potential for reducing emissions, noise pollution, and greenhouse gases (GHGs) when compared to diesel buses. Furthermore, we compared the trolleybus system with battery electric buses in terms of cost and environmental benefits. To do so, a case study was conducted in São Paulo, Brazil, the largest city in Latin America, which operates the second-highest trolleybus system on the American continent. Our results show that the trolleybus system is a feasible alternative to diesel buses when considering environmental aspects. It can be seen as a complementary service for urban transport systems in the city’s transition to clean energy. Finally, the study implications indicate the need for further investigation of the benefits of in-motion-charge technology to generate flexibility in trolleybus systems, and the involvement of stakeholders in the transition matrix energy process in urban bus systems beyond the direct costs. Full article

The urban transport network involves complex processes, operating 24 h a day and 365 days a year. The sustainable development of the urban transport network using electric buses and trolleybuses that run autonomously is an urgent task since the transport network performs integral social functions and is the transport artery of any urban center. The social and economic life of a city as a whole depends on the reliability of the transportation network. A theory is proposed for the technical and economic evaluation of reliability improvement in electric buses and trolleybuses running autonomously, which enables the determination of the reliability parameters of electric buses and forecasts for the future from the point of view of optimal economic costs for the operation of electric equipment in electric buses. As a result of the application of the proposed theory, it was found that increasing the reliability of the transportation fleet can lead to a decrease in both specific operating costs and capital investments in the development of the fleet. This is achieved as a result of increasing the annual productivity of vehicles by reducing the time they are out of service to eliminate the consequences of failures and carry out maintenance and repair. The conducted experiments confirmed that the theory and methodology of optimal reliability level selection not only enable the rational use of the material resources of the urban transport network but also the release of funds for its scientific and technical development by reducing the number of failures in the electrical equipment of transport systems by 14%. Full article

In the context of smart cities, direct current overhead contact lines, usually adopted to power urban transportation systems such as trolleybuses, tramways, metros, and railways, can serve as a backbone to connect different modern emerging technologies. Among these, in-motion charging (IMC) trolleybuses with on-board batteries are expected to be very impactful on the DC network’s power flow and may require specific voltage and current control. These factors motivate the development of a simulation tool able to emulate these devices’ absorption and their effect on the supply infrastructure. The main innovative value of the work is to improve a simulation model of a trolleybus grid through a data-driven approach by using measurements of voltage and current output from a traction substation. The measurements are essential for understanding the behavior of vehicle weight variation throughout the day. Thanks to this information, a characterization of the current draw by conventional trolleybuses and IMC trolleybuses is then provided for each trolleybus route in a specific power section of the Bologna trolleybus system. By integrating the variation in vehicle weight within the model, a simulation of a possible daily operation of a trolleybus feeding section has been performed, obtaining a 7% error between the daily energy calculated from the simulation and that obtained through measurements. This analysis demonstrates the feasibility of the adopted simulation tool, which can also be used to evaluate additional hypothetical trolleybus operation scenarios. One of these possible scenarios considers IMC vehicles, and it is also evaluated in this paper. Full article

Trolleybus systems are resurfacing as a steppingstone to carbon-neutral urban transport. With an eye on smart city evolution, the study and simulation of a proper monitoring system for trolleybus infrastructures will be essential. This paper merges the authors’ engineering knowledge and sources available in the literature on designing and modeling catenary-based electric traction networks and performs a critical review of them to lay the foundations for proposing possible optimal alternatives. A novel multi-vehicle motion-based model of the DC catenary system is then devised and simulated in Matlab-Simulink, which could prove useful in predicting possible technical obstacles arising from the next-future introduction of smart electric traction grids, inevitably featuring greater morphological intricacy. The modularity property characterizing the created model allows an accurate, detailed, and flexible simulation of sophisticated catenary systems. By means of graphical and numerical results illustrating the behavior of the main electrical line parameters, the presented approach demonstrates today’s obsolescence of conventional design methods used so far. The trolleybus network of the city of Bologna was chosen as a case study. Full article

This paper analyzes the results of a trial operation of a battery-based buffer station supporting a selected section of trolleybus power supply systems in Pilsen, Czech Republic. The buffer station aims to prevent the catenary from excessive voltage drops in a part of the route that is most remote from the traction substation. Compensation of voltage drops is carried out by continuously measuring the catenary voltage and injecting the current into the catenary if the voltage decreases below a preset value. The effectiveness of such a solution was evaluated by the analysis of numerous experimental recordings, both from the buffer station itself and from trolleybuses in operation. Further on, based on the recordings, a utilized battery capacity was estimated and a control method for decreasing the required capacity was proposed. The optimal capacity analysis, supplemented with an evaluation of required output current rating, was used to define the best storage technology for the considered application. Full article

The development of electromobility involves the development of electric cars charging infrastructure. The increase of the number of chargers poses new demands for the AC power grid, especially in regard to its capacity of delivering high peak power. As an alternative for the public AC power grid, urban electrified transportation systems (trams, trolleybuses, and metro) can be used for supplying electric cars chargers. The article discusses four options of integrating electric cars chargers with a traction power supply system. The option of connecting the charger to the traction overhead supply line has been selected due to the spatial availability of the power source and possibility to use regenerative braking energy for charging. A set of criteria has been developed for analysing the capability of the traction supply system to feed electric cars chargers. An exemplary feasibility analysis was carried out for trolleybus traction supply system in Gdynia, Poland. The impact of installing the charging station on specific traction supply parameters has been predicted using present-state recordings of electrical parameters and assumed charging station power. The study shows that every supply section of the considered trolleybus traction system has the capability of installing a fast-charging station, which provides opportunities of expanding the charging stations network in Gdynia. Full article

The paper proposes a novel approach to modeling electrified transportation systems. The proposed solution reflects the mechanical dynamics of vehicles as well as the distribution and losses of electric supply. Moreover, energy conversion losses between the mechanical and electrical subsystems and their bilateral influences are included. Such a complete model makes it possible to replicate, e.g., the impact of voltage drops on vehicle acceleration or the necessity of partial disposal of regenerative braking energy due to temporary lack of power transmission capability. The modeling methodology uses a flexible twin data-bus structure, which poses no limitation on the number of vehicles and enables modeling complex traction power supply structures. The proposed solution is suitable for various electrified transportation systems including suburban and urban systems. The modeling methodology is applicable i.a. to Matlab/Simulink, which makes it broadly available and customizable, and provides short computation time. The applicability and accuracy of the method were verified by comparing simulation and measurement results on an exemplary trolleybus system operating in Pilsen, Czech Republic. Simulation of daily operation of an area including four supply sections and maximal simultaneous number of nine vehicles showed a good conformance with the measured data, with the difference in the total consumed energy not exceeding 5%. Full article