Bus Size Research Articles

Fuel Cell Electric Buses: A Systematic Literature Review

This paper presents a comprehensive review of scientific papers and market reports analyzing the economic competitiveness of fuel cell electric buses (FCEBs) with respect to their conventional alternatives via the total cost of ownership (TCO) methodology. We discussed the variables and data taken into account and compared the resulting outcomes by year and geographical areas. It emerged that FCBs are not currently cost competitive. The decreasing trend in acquisition and fuel costs, however, indicates potential for future competitiveness. We find that the current TCO literature on FCEBs presents several areas of uncertainty and weakness. Potential improvements can be achieved by: (i) extending the geographic coverage to Asian and African developing countries; (ii) making use of real-world data instead of simulated data, in particular, concerning acquisition costs, hydrogen costs under different pathways, fuel efficiency, and maintenance costs; (iii) clarifying the role of infrastructural costs; (iv) exploring the existence of economies of scale at fleet level; (v) distinguishing among different bus sizes.

PrismParser: A Framework for Implementing Efficient P4-Programmable Packet Parsers on FPGA

The increasing complexity of modern networks and their evolving needs demand flexible, high-performance packet processing solutions. The P4 language excels in specifying packet processing in software-defined networks (SDNs). Field-programmable gate arrays (FPGAs) are ideal for P4-based packet parsers due to their reconfigurability and ability to handle data transmitted at high speed. This paper introduces three FPGA-based P4-programmable packet parsing architectural designs that translate P4 specifications into adaptable hardware implementations called base, overlay, and pipeline, each optimized for different packet parsing performance. As modern network infrastructures evolve, the need for multi-tenant environments becomes increasingly critical. Multi-tenancy allows multiple independent users or organizations to share the same physical network resources while maintaining isolation and customized configurations. The rise of 5G and cloud computing has accelerated the demand for network slicing and virtualization technologies, enabling efficient resource allocation and management for multiple tenants. By leveraging P4-programmable packet parsers on FPGAs, our framework addresses these challenges by providing flexible and scalable solutions for multi-tenant network environments. The base parser offers a simple design for essential packet parsing, using minimal resources for high-speed processing. The overlay parser extends the base design for parallel processing, supporting various bus sizes and throughputs. The pipeline parser boosts throughput by segmenting parsing into multiple stages. The efficiency of the proposed approaches is evaluated through detailed resource consumption metrics measured on an Alveo U280 board, demonstrating throughputs of 15.2 Gb/s for the base design, 15.2 Gb/s to 64.42 Gb/s for the overlay design, and up to 282 Gb/s for the pipelined design. These results demonstrate a range of high performances across varying throughput requirements. The proposed approach utilizes a system that ensures low latency and high throughput that yields streaming packet parsers directly from P4 programs, supporting parsing graphs with up to seven transitioning nodes and four connections between nodes. The functionality of the parsers was tested on enterprise networks, a firewall, and a 5G Access Gateway Function graph.

A novel approach for techno-economic reliability oriented planning and assessment of droop-control technique for DG allocation in islanded power distribution systems

An effective planning strategy for deploying distributed generators (DGs) provides economic advantages through optimal net present cost (NPC), improved technical performance, enhanced voltage profile, and minimized line losses. Nevertheless, technical performance varies based on the control techniques implemented for power regulation in DGs. Therefore, it is crucial to incorporate DG control strategies for efficient and robust power distribution system planning. This study discusses a novel approach for techno-economic reliability-oriented planning in an IEEE-33 bus droop-controlled islanded power distribution system. The presented study evaluates the influence of incorporating control techniques on the sizing and placement of DGs along with the technical, economic and reliability parameters. The problem formulated for optimal DG allocation aims to achieve the optimum NPC, minimize line losses, improve system reliability, and ensure voltage and frequency agreement with IEEE std 1547™-2018. The problem formulation is structured as a multi-objective problem and is solved using the particle swarm optimization (PSO) technique to achieve optimal bus location and size for DG installation. The study reveals that considering the control strategy helps in achieving efficient and reliable planning structure.

Field Study to Design Public Transportation Network for One of the Libyan Cities (The City of Houn is an Example)

The cultural and urban development that the cities of the world in general have experienced over the years, including the Arab countries, has led to the existence of many urban problems, including urban transportation problems, mainly represented by traffic congestion, noise, and environmental pollution in all its visual and audio forms. Through this, the need for many systems to manage life aspects within these cities emerged from a social, economic and political perspective, including public transportation systems, which are considered one of the most important causes of urban stability in many cities of the world, whether developed or developing countries. The urban transportation system in Libya (as one of the developing countries in the world) suffers from the lack of planning based on scientific foundations for the transportation system - especially the public transportation network - that takes into account data collected in the field on how to design public transportation time tables according to the number of passengers, the length of the line, the trip time, and the number of buses in public transportation network, hence the need to conduct such a field study to plan public transportation networks within Libyan cities is very important. In this study, the city of Houn was chosen as a model for designing a public transportation network. The methodology was divided in two stages. The first stage was for data collection. A questionnaire (1080 surveys) was conducted for the main and active places in the city, including (educational, service, and employment places), as well as traffic counts were conducted by monitoring and recording traffics in the field during the morning and evening peak periods. The second stage was for analyzing and studying the data using Excel program, converting them into charts, comparing and studying the collected data. Based on analyzing and studying the data, the study concluded with the design of public transportation network in which the bus route for the network was determined, the locations and number of bus stops were determined, taking into account the required distances between stations. In addition, the number of buses was determined as well as the size of buses and the frequency of buses for morning and evening peak periods. Keywords: public transportation, questionnaire, traffic counts, peak hours

Few‐shot learning for satellite characterisation from synthetic inverse synthetic aperture radar images

AbstractSpace situational awareness systems primarily focus on detecting and tracking space objects, providing crucial positional data. However, understanding the complex space domain requires characterising satellites, often involving estimation of bus and solar panel sizes. While inverse synthetic aperture radar allows satellite visualisation, developing deep learning models for substructure segmentation in inverse synthetic aperture radar images is challenging due to the high costs and hardware requirements. The authors present a framework addressing the scarcity of inverse synthetic aperture radar data through synthetic training data. The authors approach utilises a few‐shot domain adaptation technique, leveraging thousands of rapidly simulated low‐fidelity inverse synthetic aperture radar images and a small set of inverse synthetic aperture radar images from the target domain. The authors validate their framework by simulating a real‐case scenario, fine‐tuning a deep learning‐based segmentation model using four inverse synthetic aperture radar images generated through the backprojection algorithm from simulated raw radar data (simulated at the analogue‐to‐digital converter level) as the target domain. The authors results demonstrate the effectiveness of the proposed framework, significantly improving inverse synthetic aperture radar image segmentation across diverse domains. This enhancement enables accurate characterisation of satellite bus and solar panel sizes as well as their orientation, even when the images are sourced from different domains.

Optimum ground-mounted on-grid connected photovoltaic system

This research endeavors to enhance grid-connected solar photovoltaic systems by refining the methodology used to select suitable geographical photovoltaic sites. The prevalent criterion in existing literature for choosing sites emphasizes proximity to power transmission lines. However, this criterion overlooks essential grid requirements, such as approved bus bars and permissible sizes for new photovoltaic systems. To overcome this limitation, the study introduces a novel criterion. Instead of relying solely on proximity to transmission lines, the proposed approach replaces this with the concept of optimal geographical bus bar locations. Additionally, the generated findings can be fine-tuned through consideration of the specified system size of the grid, thereby improving the identification of geographically suitable sites more effectively.The proposed methodology lies in the incorporation of five distinct approaches. The primary approach employs the Artificial Bee Colony (ABC) algorithm to ascertain the most suitable bus bars and sizes for three Photovoltaic Distributed Generation (PV-DG), with a focus on minimizing power loss within Aden's electric grid. The second approach involves utilizing the Analytic Hierarchy Process-Weighted Linear Combination (AHP-WLC) method in conjunction with Geographic information systems (GIS) to accurately select appropriate PV sites. The third approach is an initial design to eliminate small geolocations that do not align with the PV system's size. Fourthly, the Least Costly Path Model (LCPM) is harnessed to choose a single geolocation. The final approach is dedicated to performing techno-economic analysis.The key findings reveal that the optimal bus bars are located at 30, 46, and 64 in the grid, with a total injected active power of 26 MW. Simultaneously, the identified optimal geolocations cover areas of 0.88, 0.48, and 1.37 km^2 for each bus bar, respectively. In the comparative analysis, the utilization of the proposed criterion involving optimal bus bars results in a larger geographical coverage (97.99 km2) compared to the traditional criterion (76.28 km2). Furthermore, the techno-economic evaluation indicates the viability of implementing PV systems in Aden.The authors have a strong conviction that the framework and outcomes of this study will garner significant attention and prove valuable in assisting decision-makers to improve the planning of grid-connected solar photovoltaic systems.

A review on security implementations in soft-processors for IoT applications

With the increase in the number of devices connected to the Internet, the need to maintain and harden information security in Internet systems has significantly increased. This has led to the development of hardware systems that implement security services. Therefore, from a taxonomy to sort and classify the key criteria to processor design, an overview and in-depth analysis of soft-processors that implement algorithms for Internet of Thing applications is presented highlighting their advantages and disadvantages to be used in larger systems. In order to perform a systematic review of the engineering literature related to the interest topic in this work, a bidirectional review methodology consisting of the following three phases has been proposed and applied: review planning, review conducting, and review reporting. Then, soft-processor architectures implementing security algorithms are compared considering computational cost, speed, bus size, number of pipeline stages, and performance. Finally, based on a feature analysis, the strengths and threats of soft-processors when implementing information security for Internet of Things applications are discussed, and the LORS design model is proposed to lead to recommendations for future designs.

Optimal Overall Dimensions of a Surface Acoustic Waves Ring Resonator

Introduction . In previous works, the authors considered the frequency characteristics of sensitive elements made of various materials in the form of a ring resonator on surface acoustic waves (SAW), along with their fixing methods in the housing, the influence of external factors, and an optimal topology of the interdigital transducer of the ring resonator. Further, the need arose to study the dependence of the sensitivity of the sensitive element and the maximum acceleration load on its dimensions, as well as to analyze the characteristics of the manufactured experimental samples in comparison with the simulated values. Aim . To determine optimal dimensions of the sensitive element of a ring resonator and to confirm the adequacy of the constructed models by comparing the characteristics of experimental samples with those obtained by computer simulation. Materials and methods . The theoretical part of the research was carried out using the finite element method. Mathematical processing was implemented in AutoCAD and COMSOL Multiphysics. Results . Three overall dimensions of the sensitive element of a ring resonator were proposed: 1500, 3000 and 4500 µm. The characteristics of sensitive elements made of lithium niobate with the above dimensions were studied. Thus, the resonance frequency for 1500, 3000 and 4500 µm samples comprised 207.99, 104.10 and 68.99 MHz, respectively. The maximum acceleration experienced by a cantilever with a radius of 1500, 3000 and 4500 µm was found to be 191 132, 84 958 and 37 514g, respectively. Dependence graphs of the maximum acceleration and sensitivity on the ratio of the radius of the console to its height are presented. The adequacy of the constructed model was confirmed, i. e., the resonance frequency for 1500, 3000 and 4500 µm experimental samples comprised 218.17 MHz (4.67 % discrepancy with computer simulation), 109.23 MHz (4.69 %) and 72.88 MHz (5.34 %), respectively. Conclusion . The sensitivity and maximum acceleration load of the sensitive element of a SAW ring resonator directly depends on the ratio of the cantilever radius to its height, with higher sensitivity values correlating to lower values of maximum acceleration load. For each material, these dependencies are unique. The interdigital transducer bus size has little effect on the frequency response. The previously presented simulations were confirmed by experimental samples with a difference in resonance frequencies of less than 5.5 %.

Optimization of a rural bus service integrated with e-commerce deliveries guided by a new sustainable policy in China

Electronic business has expanded, resulting in flourishing rural e-commerce globally, and particularly in China. This paper introduces a novel rural public transit system that integrates passenger and freight services—a rural electric bus service that provides services for passengers and e-commerce packages. This blended service reduces logistical costs and generates additional income for the transit operator. The objective is to minimise cost for the transit user and operator by using a mixed-integer linear programming model that solves bus routing and bus trip scheduling for multiple rural towns; in addition, the model is tested by the Gurobi solver at small-scale instances. The developed solution is a hybrid heuristic algorithm based on adaptive large neighborhood search and tabu search approaches. Finally, a case study in China is conducted to examine the proposed cost-effective methodology and ensure that the integrated scheme will significantly save operational system costs without causing any passenger inconvenience. The research also shows how to optimally design the size of rural electric buses to reduce purchasing and maintenance costs. The optimal results of the case study, comprising 5 towns and 78 villages, show an annual cost saving of approximately ¥847,000 (approximately $121,000) and an annual mileage saving of approximately 66,000 km for the proposed scheme. In addition, the case study explicates key parameters selected for transfer package requirements and the effective deployment of the proposed scheme.

Fast QC Relaxation of the Optimal Power Flow Using the Line-Wise Model for Representing Meshed Transmission Networks

In this paper, we investigate the recently introduced McCormick-based Quadratic Convex (QC) relaxation of the Optimal Power Flow (OPF) where Line-Wise Model (LWM) is used for representing meshed transmission systems (QC-LW OPF) for the sake of decisively determining its relationship to other available convex relaxations in the literature. We also extend the recently introduced convex envelope of the tangent function so it would be suitable for test cases with any voltage angle difference range. A computational study where the recently proposed QC-LW OPF formulation is compared to an equivalent McCormick based QC relaxation of the OPF where Bus Injection Model (BIM) is used for representing meshed transmission systems (QC-BI OPF) is presented in this paper. This computational study was conducted using test cases that belong to different operational categories using 123 test cases from the PGLib-OPF library with a bus size range between 3 up to 6515 buses for the sake of understanding the effect of the change of operating conditions on the quality of solutions obtained using the QC-LW OPF and QC-BI OPF formulations. Results are compared using several metrics that testify to the obtained solution’s quality and the problem’s computational complexity. Comparison of results shows that the QC-LW relaxation neither dominates nor is dominated by the QC-BI relaxation in terms of solution quality. Therefore, it dominates the Second Order Cone (SOC) relaxation and neither dominates nor is dominated by the Semidefinite Programming (SDP) relaxation. Furthermore, it is shown that the QC-LW OPF has reduced the number of relaxed trigonometric functions and McCormick envelopes needed when compared to the QC-BI OPF, leading to a faster solution time for more than 84% of the test cases in the range of 2% up to 67%.

A Comparison of Pattern Recognition and Probabilistic Techniques for Capital Asset Deterioration

Capital asset management is a critical component of the operation of transit systems. In particular, much interest has been generated lately regarding the development of rolling stock deterioration models that can predict the future condition of a fleet from the corresponding deterioration curves. Based on a rolling stock inspection data set from Athens, Greece, this paper presents the development of both an ordered probit model and a predictive discriminant function that can be invaluable tools in predicting rolling stock deterioration. This combination of models provides a way in which we can get both aggregate (system level) projections on future bus conditions and disaggregate (individual bus level) projections. Both of the methodologies used recognize the ordinal nature of condition ratings and link deterioration to a set of relevant explanatory variables such as bus age, mileage, and size. The results can be easily used in a number of practical situations, such as capital asset life-cycle cost analysis, optimal timing for bus replacement, and examination of the effect of different operational strategies on bus deterioration.

Fatbergs [waste - solutions

Fatbergs are a nuisance and, quite frankly, disgusting. How can we find the root of the problem and solve it? Every day beneath the streets of London, sewer cleaners are fighting a grim war against giant 'fatbergs' clogging the system. Fatbergs are rock-like heaps of waste that build up in sewer systems thanks to the unsavoury and lazy habits of humans. Cooking fat and oils poured down sinks congeal in the sewers, forming a thick layer around pipes. This fatty build-up stops sewage from flowing freely, which can cause it to back up. But it's the addition of non-biodegradable solids such as wet wipes and nappies that, when mixed with the fat, create hard fatbergs capable of growing to the size of buses and completely blocking sewage systems. In short, it's one disgusting recipe for disaster.

Hybrid Grey Wolf Optimizer Based Optimal Capacitor Placement in Radial Distribution Systems

The problem of optimal capacitor placement (OCP), or the determination of both the optimal bus locations and sizes in radial distribution systems (RDS) has been solved in this article using a new metaheuristic algorithm named as the hybrid grey wolf optimizer (HGWO). The grey wolf optimizer (GWO) is hybridized with the addition of mutation and crossover, to create the hybrid grey wolf optimizer (HGWO). The enhanced performance of the HGWO has been proved by comparison of the solutions and the convergence curves of GWO and HGWO. The objective of the OCP problem—a discrete, non-convex optimization problem—is minimization of the cost of capacitor installations and total real power loss. The proposed HGWO approach has been applied to solve the IEEE 34-, 69-, 119 bus RDSs and a practical 22-bus RDS. Comparisons of the results obtained against those reported in the literature show that the HGWO performs very well, and hence is a highly suitable optimization approach for solving OCP problems.

Fast SDP Relaxation of the Optimal Power Flow Using the Line-Wise Model for Representing Meshed Transmission Networks

In this paper, we propose a novel Semidefinite Programming (SDP) relaxation of the Optimal Power Flow (OPF) problem. The proposed formulation utilizes the Line-Wise Model (LWM) to represent meshed transmission networks. This allows the constraints of the proposed formulation to mostly depend on diagonal elements of the voltages&#x0027; Hermitian <inline-formula><tex-math notation="LaTeX">${\bm{W}}$</tex-math></inline-formula> matrix in contrast to the Bus Injection Model (BIM) where constraints heavily utilize its off-diagonal elements. Test cases with bus sizes of 3 to 9241 were considered and chordal sparsity was exploited for them. Obtained results show that the proposed SDP-LW OPF formulation manages to provide solutions of similar or better quality for most test cases that belong to the Typical and Congested (TYP and API) Operating conditions. Furthermore, the proposed SDP-LW OPF formulation manages to reduce the solver&#x0027;s computational time for most of large-scale test cases with reductions up to 80.298&#x0025;. Results analysis shows that reductions in the solver&#x0027;s computational time upon using the proposed SDP-LW OPF formulation are affected by its ability to significantly reduce constraints with off-diagonal elements of the <inline-formula><tex-math notation="LaTeX">${\bm{W}}$</tex-math></inline-formula> matrix without drastically increasing constraints with diagonal elements of the <inline-formula><tex-math notation="LaTeX">${\bm{W}}$</tex-math></inline-formula> matrix. Furthermore, the percentage of large sized cliques is found to affect the obtained reductions through its influence over the number of needed linking constraints for relating the elements of the <inline-formula><tex-math notation="LaTeX">${\bm{W}}$</tex-math></inline-formula> matrices of decomposed cliques.

Optimization Model of Transit Route Fleet Size Considering Multi Vehicle Type

This paper proposes a bus line capacity optimization design model considering the scale of multiple vehicles, which is achieved by minimizing system operating costs and user costs. The proposed model takes into account the difference of passenger demand in different periods, and can get the optimal headway and delivery and reserve plan. In order to prove that the method can effectively minimize the cost, we solved a numerical example and compared the cost of the method in multi-transit model planning. Furthermore, the optimization results show that the total costs (TC) were reduced by 14.48%. Among them, the user costs (UC) decreased by 30.38% and the operator costs (OC) increased by 4.18%. Sensitivity analyses are presented to verify the validity of the model. The analysis results show that multi size bus optimization can reduce the total cost, especially the user cost in a certain cost weight interval. Besides this, the cost weight which reflects the passenger volume and waiting time value, optional bus size and cross-section passenger volume all affect vehicle scheme and system cost.

Research on power system transient stability with wind generation integration under fault condition to achieve economic benefits

For a few decades, electric power growth and demand have increased globally. To fulfil this demand, distribution generators (DGs) have been installed in the power system. To get numerous benefits such as comprising reduction of power losses, improvement of (voltage, current, rpm) transient stability, leads to economic benefits. DGs integration in the distribution power system (DPS) was reported as an optimal generator placement (OGP) problem to maximize these benefits. This paper performs wind turbine (WT) integration while considering the internal generator's (rpm) transient stability under fault conditions. A power loss index (PLI) method is implemented to select potential candidate buses for generator placement. A self-sorting analytical approach (SSA) is also used to determine the optimal bus and WT size. The IEEE 14-bus DPS is used as the OGP test system to demonstrate the proposed method's effectiveness in terms of power losses reduction, system transient stability, and economic benefits. The IEEE 14 Bus system was considered using MATLAB with a 3.2 GHz processor to perform the said approach. WT integration suggested in case-2 results in a 65.80% power losses reduction, which leads to a 60.88% enhancement of economic benefits of the DPS.

The depot and charging facility location problem for electrifying urban bus services

• The depot and facility location problem is formulated for deploying electric and diesel buses. • Cost components in the transition from diesel buses to electric ones are evaluated. • Depot locations highlight the trade-off between deadhead mileage and land cost. • The required ratio of electric buses is a key factor in the total operational cost. • The bus fleet size affects the cost and robustness of system operation. The transition from diesel-consuming buses to electric ones entails the problem of determining the locations of bus depots, charging and maintenance stations, which can directly affect the operating cost and efficiency of a bus system. The problem also involves practical concerns, including the selection of fleet size (of electric buses), land acquisition, bus allocation, and the associated deadhead mileage. This study develops an optimization model to systematically locate depots and relevant facilities for deploying mixed types of vehicles. Further, a decomposition-based heuristic algorithm is proposed to enhance computational efficiency. A case study is performed using the data of a bus operator in Taiwan. Sensitivity and scenario analyses are conducted, evaluating major cost components and identifying the factors that affect the trade-offs between them. The proposed methodology enables bus operators/planners to closely and holistically examine their decisions during the transition toward electric bus systems.

Voltage Stability Index Using New Single-Port Equivalent Based on Component Peculiarity and Sensitivity Persistence

A voltage stability index is proposed using a new single-port equivalent depending on component peculiarity representation and sensitivity persistence to locate and determine long-term voltage instability in transmission and distribution power networks. The suggested single-port equivalent effectively represents the equivalence of various component types and assures the consistency of sensitivity information before and after the equivalence which is compulsory for the equivalent accuracy in estimating the voltage stability analysis. The stability index is derived from the new single-port equivalent to determine the system voltage instability. The proposed stability index is compared with indices based on virtual impedance and Thevenin impedance models. This new stability index shows more accuracy and effectiveness as compared to the indices based on virtual and Thevenin equivalent models. The index also determines the weak buses, where an improvement or functional measure can be used to reduce the system voltage instability. The validity of the proposed equivalent approach and stability index is presented by utilizing two radial systems, four IEEE systems and an actual system having bus size from five to 1010 buses.

Identification of Factors to Improve Public Transit Services (A Case Study of Prithvi Chowk to Talchowk Section of Prithivi Highway)

This research presents studies on a segment of highway to determine the quantitative factors that inuence transit services. Travel time and delay study is one of the method to determine quantitative factors. Tour time is described as the average period of time required to journey from one region to some other. Total departure time consists of gadgets which include total working time, places and general delay time. The examine section was done in Prithvi chowk to Tal chowk of Prithvi Highway which is turned to be 12.5 km long. Additionally, it has been found that the principle variables affecting travel time are: postpone time because of forestall selecting and choosing up passengers, bus model and bus size.32 trips public transport carrier and a 10 trips non-public automobile journey have been held during peak hours. Models are developed the use of SPSS software to become aware of the relationship between the causes of delays and the overall-time delays. Travel time and learning delays can help reduce the number of private vehicles operating and increase the number of public vehicles in order to reduce congestion and improve the e efficiency of the public transport system. It turned into determined that there was a full-size distinction in tour time among the use of the public transit services and the car.

Vehicle dispatching plan for minimizing passenger waiting time in a corridor with buses of different sizes: Model formulation and solution approaches

Urban public transportation agencies sometimes have to operate mixing vehicles of different sizes on their routes, due to resource limitations or historical reasons. Services with different passenger-carrying capacities are provided to passengers during a mixed-fleet operation. A fundamental question arising here is how to optimally deploy a given fleet of different bus sizes to provide services that minimize passenger waiting time. We formulate a mixed-fleet vehicle dispatching problem as a Mixed-Integer Nonlinear Programming (MINLP) model to optimize dispatching schemes (dispatching orders and times) when a given set of buses of different sizes are available to serve demand along a route. The objective is to minimize the average passenger waiting time under time-dependent demand volumes. Stochastic travel times between stops and vehicle capacity constraints (i.e., introducing extra waiting time due to denied boarding) are explicitly modeled. A Simulated Annealing (SA) algorithm coupled with a Monte Carlo simulation framework is developed to solve large real-world instances in the presence of stochastic travel times. Results show that, in addition to dispatching headway, bus dispatching sequence can strongly affect waiting times under a mixed-fleet operation. Indeed, with an optimal dispatching sequence, a more accurate adjustment of supply to demand is possible in accordance with time-dependent demand conditions, and the total savings in waiting time are mainly driven by a further reduction in the number of passengers left behind. The optimality of uneven dispatching headways stems from two elements: having a mixed fleet and having localized peaks on demand that make buses run full.