Typical Bus Research Articles

Predicting energy consumption of zero emission buses using route feature selection methods

This paper reports new insights into how the selection of route based characteristic parameters can influence the predicted energy consumption for next generation battery electric buses. 24 characteristic parameters have been studied to understand their relative importance on vehicle energy consumption and to develop new data-driven prediction models. The parameters are grouped into two scenarios, representative of the varying levels of route information available to a typical bus operator. A combination of feature selection methods was used to determine which characteristic parameters had the greatest influence on energy consumption. Regression based prediction models were developed, and models were then validated using standard and real vehicle drive cycles. The prediction models had a mean absolute percentage difference of 2.10–10.67%. This paper presents a novel methodology to estimate energy consumption of operating zero emission vehicles, which will support public transport operators, policy makers and energy suppliers in the decarbonisation of public transport.

Analysing the modal competitiveness of public transport through the concept of generalised journey time

Amongst a range of factors, travel time of the bus relative to the equivalent journey in the private car is considered the strongest predictor in the selection of travel mode. In order to incentify a shift toward more sustainable modes of transportation, the bus must decrease its travel time to compete with the car and attract and retain ridership. There is limited literature on the travel time ratio between the car and the bus, and very little work that addresses this issue in the context of Ōtepoti Dunedin. It is a complicated area of research that has no simple answer, as there is no single measure of time related quality of the typical bus service. This report uses the concept of Generalised Journey Time - which recognises that a single bus journey is a multimodal trip and breaks the journey into different stages. It then makes policy and governance suggestions that focus on the broader picture and aim to foster the delivery of a faster and more attractive public transportation system in Ōtepoti Dunedin. Increased public transport usage will reduce the reliance on global fossil fuel markets, generating cities that align with modern, sustainable, environmentally conscious visions. 
 Supervised by Ray O'Brien & Craig Cliff, Sustainability Office, University of OtagoScholarship funded by: Dunedin City Council

Revealing safety impact of bus stops on passenger-cyclist interactions – Evidence from Nanjing, China

Bus passengers and cyclists often interact with each other at bus stops, which causes potential conflicts and safety risks. However, the safety impact of different types of bus stops on vulnerable road users has received limited attention. This study measures the safety impact of different types of bus stops on the interactions between passengers and cyclists. 3,136 passengers and 4,135 cyclists are observed at twelve typical bus stops in Nanjing, China. Road users’ behaviours, safety risks and congestion levels at different types of bus stops and their influential factors are analysed. Logit model and partial proportional odds model are used to analyse the occurrence rate and the severity of passenger-cyclist conflicts, respectively. Results indicate that generally floating bus stops with dedicated cycleway provide a safer environment for vulnerable road users, compared to curbside bus stops. Many factors are found increasing the safety risk significantly, including narrow road width, passengers using mobile phone, wrongful riding direction of cyclists, high passenger or cyclist densities, and passenger-cyclist interaction in cross direction. There is also a significant difference on the lag-time of road users at different types of bus stops. It is recommended that the layout design of bus stops should provide sufficient space for road users, and various regulations could be taken into consideration to alleviate the conflicts at bus stops and protect the safety of both passengers and cyclists.

Life-Cycle Assessment in the LEED-CI v4 Categories of Location and Transportation (LT) and Energy and Atmosphere (EA) in California: A Case Study of Two Strategies for LEED Projects

This study aimed to identify different certification strategies for Leadership in Energy and Environmental Design Commercial Interior version 4 (LEED-CI v4) gold-certified office projects in California’s cities and to explore these certification strategies using life-cycle assessments (LCAs). The LEED-CI v4 data were divided into two groups: high- and low-achievement groups in the Location and Transportation (LT) category. The author identified two strategies for achieving the same level of certification across LEED-CI v4 projects: (1) high achievements in LT (LTHigh) and low achievements in the Energy and Atmosphere (EA) category (EALow), and (2) low achievements in the LT category (LTLow) and high achievements in EA (EAHigh). The author adopted LTHigh–EALow and LTLow–EAHigh achievements as functional units for LCA. Three alternatives were LTHigh: typical bus, EALow: gas; LTLow: typical car, EAHigh: gas; and LTLow: eco-friendly car, EAHigh: gas, where a typical bus used diesel, a typical car used natural gas, an eco-friendly car used EURO5diesel, and natural gas was used as a building’s operational energy. The ReCiPe2016 results showed that the LTHigh: typical bus, EALow: gas strategy was preferable from a short-term perspective, and the LTLow: eco-friendly car, EAHigh: gas strategy was preferable in a long-term and an infinite time perspective, while the LTLow: typical car, EAHigh: gas strategy continued to be the most environmentally damaging certification strategy for all the time horizons of the existing pollutants. Thus, it can be concluded that if there are alternative strategies for LEED certification, an analysis of their LCAs can be useful to refine the best sustainable strategy.

Observational study on multi-type conflicts between passengers and cyclists at the bus stop – A case study in Nanjing

Dedicated cycleway is usually used to keep cyclists away from motorised vehicles in some countries like China. As a result, potential traffic conflicts between bus passengers and cyclists are frequently observed, which lead to potential safety issues for both passengers and cyclists. To our best knowledge, such conflicts and potential safety risk at the bus stop have received rare investigation. More specifically, multi-type conflicts caused by passengers converging from different directions with heterogeneous route choices lack proper research. To fill the gap, this study aims to investigate interactions and conflicts between bus passengers and cyclists. Unobtrusive observations and data collection are conducted by video recordings at a typical bus stop in Nanjing CBD, China. Trajectories of passengers and cyclists are extracted to analyse their interactions, conflicts, and potential safety risks. Lag-time and time-to-collision are adopted as indicators to evaluate the cycleway congestion and severity degree of conflicts, respectively. Multiple influential factors are analysed to evaluate their impacts to congestion and safety risk at a bus stop. The analysis results show that high density of passengers and cyclists, the behaviour of passengers walking along the right side of cycleway, and the interaction between passengers and cyclists crossing from behind or side will increase safety risk. The research findings suggest that bus stop layout design should consider clear view for crossing passengers and passing cyclists; sufficient space should be provided for waiting passengers; and crosswalk should be designed properly to guide passengers to cross cycleway and protect cyclists’ and passengers’ safety.

Development of Bus Driving Cycle for Debrecen on the Basis of Real-traffic Data

In the literature it has been proven several times, that the common driving cycles are not accurate enough to estimate the fuel and energy consumption data or emission data for vehicles, especially for public transport vehicles, such as buses. One can find driving cycles for buses, but the special driving environment in Debrecen, Hungary cannot be accurately represented by them. As a part of a project focusing on the determination of fuel and energy consumption of vehicles by dynamic simulation, a study has been carried out for determining driving cycles, which are representative for Debrecen. In this paper the development of a driving cycle for city buses in Debrecen is presented. Typical bus routes were selected in the town for the study, the vehicles were instrumented with an appropriate data collecting system. These onboard units were used to collect data such as travelled distance, speed and acceleration on several vehicles in the real-world traffic. We used special purpose software to pre-process and filter the collected data. After pre-processing a statistical evaluation of the data was carried out. Using a version of the widely spread micro-trip method of driving cycle development, a Bus Driving Cycle has been constructed for Debrecen.

СОЦИОЛОГИЧЕСКИЕ АСПЕКТЫ СРЕДНЕСРОЧНОЙ ДИНАМИКИ ОРГАНИЗОВАННОСТИ ПЕРЕВОЗОЧНОГО ПРОЦЕССА НА ГОРОДСКИХ АВТОБУСНЫХ МАРШРУТАХ ТЮМЕНИ

The paper presents results of studies dedicated to influence of structure of passengers transported by city public transport on transportation process organization that is assessed by relative entropy Hn. On the example of analysis of transportation structure for two typical bus routes in Tyumen the author has established that at increase of share of privileged passengers general organization of transportation process grows. However, the studies show that middle-term organization trends (2017-2021) are unfavourable - the level of system chaos increases.

CFD Investigation of Vehicle’s Ventilation Systems and Analysis of ACH in Typical Airplanes, Cars, and Buses

The simulation of the ventilation and the heating, ventilation, and air conditioning (HVAC) systems of vehicles could be used in the energy demand management of vehicles besides improving the air quality inside their cabins. Moreover, traveling by public transport during a pandemic is a concerning factor, and analysis of the vehicle’s cabin environments could demonstrate how to decrease the risk and create a safer journey for passengers. Therefore, this article presents airflow analysis, air changes per hour (ACH), and respiration aerosols’ trajectory inside three vehicles, including a typical car, bus, and airplane. In this regard, three vehicles’ cabin environment boundary conditions and the HVAC systems of the selected vehicles were determined, and three-dimensional numerical simulations were performed using computational fluid dynamic (CFD) modeling. The analysis of the airflow patterns and aerosol trajectories in the selected vehicles demonstrate the critical impact of inflow, outflow, and passenger’s locations in the cabins. The CFD model results exhibited that the lowest risk could be in the airplane and the highest in the bus because of the location of airflows and outflows. The discrete CFD model analysis determined the ACH for a typical car of about 4.3, a typical bus of about 7.5, and in a typical airplane of about 8.5, which were all less than the standard protocol of infection prevention, 12 ACH. According to the results, opening windows in the cars could decrease the aerosol loads and improve the low ACH by the HVAC systems. However, for the buses, a new design for the outflow location or an increase in the number of outflows appeared necessary. In the case of airplanes, the airflow paths were suitable, and by increasing the airflow speed, the required ACH might be achieved. Finally, in the closed (recirculating) systems, the role of filters in decreasing the risk appeared critical.

Information entropy evaluation model of bus-line reliability considering the combination of bus stops and bus travel time

Evaluating the reliability of a bus line can provide useful information on the service performance of the city’s bus transit system and the need for improvements. This paper presents a reliability evaluation model of a bus line based on information entropy. The model integrates the weighted bus-stop index and the variation index of bus travel time. To better determine the weights of the bus stop, six indices were established based on three characteristics: passenger flow, bus-stop properties, and the environment. The proposed model was applied to typical bus lines in Fuzhou, People’s Republic of China. The results show that most bus-stop reliabilities at the peak period were smaller than those at the off-peak period. In addition, for either peak or off-peak period, the reliability shows a slight upward trend following a gradual decline after the first stop, generally reflecting the influence of passenger flow, environment, and location factors.

Effects of dowel bars misalignment in jointed plain concrete pavements – A numerical analysis considering thermal differentials and bonded slab-base interface

Abstract Joints in concrete pavements are built to allow slab volumetric variations avoiding random cracks. Moreover, as they are discontinuities, the use of dowel bars prevents loss of load transfer across joints. During bars installation or even concrete casting, misalignments and misallocations of those devices may occur, affecting the concrete pavement structural performance. This study explores the effects of such non-conformities in the positioning of dowel bars through numerical modeling, using the 3D finite element program EverFE2.25. For, numerical simulations, bending stresses in concrete slabs of a typical bus corridor were ascertained, varying misalignments types and magnitudes (vertical tilt and horizontal skew), base type (cemented and asphalt), slab/base interface bond conditions and concrete thermal differential. Results disclosed the contribution of using bonded base in reducing stresses, even when the dowels were severely misaligned while slabs were subjected to high thermal differentials.

A new type of improved four-node DKT thin-shell element and the improvement research on the fast algorithm for bus rollover collision

To solve the problem of seriously element wrap during the finite element analysis process of bus rollover collision, the wrap modification improvement of a new type of four-node DKT (Discreted Kirchhoff Theory) thin-shell element is carried out. The new type of improved four-node DKT thin-shell element is applied to the one-step algorithm for bus rollover collision, and the rollover collision simulation is carried out for the typical bus body section of a 12-m bus body structure. The simulation result is compared with the original one-step algorithm for bus rollover collision. The result shows that the simulation efficiency of the improved one-step algorithm for bus rollover collision is about 50% higher than that of the original algorithm, and the computational precision is increased by about 3.2%. The effectiveness of actual engineering application of the new type of improved element is verified in the end.

Mobile application for bus operations controlled by passengers: A user experience design project (UX)

The bus system accounts for a significant part of trips in the city of Sao Paulo. However, in recent years the percentage of users has been falling concerning the growth modes such as individual transport and the new modes of transport on-demand based on applications. The loss of attractiveness is associated with users' negative perceptions of the quality of the service provided. One of the complaints is the recurring occurrences of buses that do not halt at the stop, even when the user signals his intention to embark or disembark. One way to address this problem would be to use technology like on-demand mobility services based on mobile applications. Although the idea itself seems to be simple, there is no report to date about a fixed route bus service that has implemented a bus hailing application that allows the user the possibility of requesting a bus to halt at a given stop. This paper proposes a new operation model of fixed-route buses that ensures the user requests fulfillment. The proposed model consists of functionalities that make the bus user visible to the operation, creating a more reliable connection between drivers and users. We evaluated the specified functionalities by a group of typical bus users in Sao Paulo, using a User Experience (UX) method. The evaluation clearly showed users' needs and desires regarding the features they would appreciate in the application. We collected clear evidence of the usefulness or not of the improvements suggested by users. Based on the study, we concluded that users agreed with the need to have greater control over their bus trips, in particular, to ensure that their intentions are adequately served and have a confirmation of the recognition of their requests. The study may become an interim solution that may be applied to existing bus services by taking them closer to on-demand services and MaaS (Mobility as a Service).

Distributed Stability Conditions for Power Systems With Heterogeneous Nonlinear Bus Dynamics

This article derives distributed conditions that guarantee the system-wide stability for power systems with nonlinear and heterogeneous bus dynamics interconnected via power network. Our conditions require each bus dynamics should satisfy certain passivity-like conditions with a large enough passivity index, a sufficient requirement of which is dictated by the steady-state power flow. The passivity indices uniformly quantify the impacts on the system-wide stability of individual bus dynamics and the coupling strength from the power network. Furthermore, taking three typical bus dynamics as examples, we show that these conditions can be easily fulfilled via proper control design. Simulations on a rudimentary 3-bus example and the IEEE 39-bus system well verify our results under both small and large disturbances.

Adaptive Control Strategy Extracted from Dynamic Programming and Combined with Driving Pattern Recognition for SPHEB

An appropriate control strategy can play an important role in further improving the fuel economy performance of hybrid electric vehicle (HEV). This research developed a novel adaptive control strategy to achieve optimal power distribution for a series-parallel hybrid electric bus (SPHEB) to adapt driving pattern instantaneously. First, a methodology of extracting mode transition control and power distribution strategy from dynamic programming (DP) solution is proposed for the development of the hierarchical energy management strategy. A SPHEB energy management problem under the Chinese typical bus driving schedule at urban district (CTBDS_UD) is investigated as a case study. Second, an approach of driving pattern recognition (DPR) module is developed. For adaptive learning, four typical driving patterns are selected as the database of driving condition and using the extraction method described above to acquire optimal control strategies for four driving patterns. Third, a framework of adaptive control strategy has been proposed based on the extracted hierarchical energy management strategy from DP and combined with DPR. Finally, the simulation results demonstrate the proposed adaptive strategy can make power distribution proper adjustments in real time and be capable of improving significantly the fuel efficiency of the SPHEB.

Direct Liquid Cooling Method Verified With a Permanent-Magnet Traction Motor in a Bus

Direct liquid cooling (DLC) of electrical machine windings is a clearly effectual cooling method for high-torque and high-power-density applications needed, especially, in heavy vehicles. Usually, in electric vehicles, the stator copper winding losses are the most dominating losses during the accelerating or decelerating (recuperation) modes, and therefore, traditional windings may heat up significantly during high-torque periods. Removing the heat directly from the winding in which most of the heat is generated allows the most straightforward and effective way of cooling. This paper investigates the feasibility of the DLC in a radial-flux permanent-magnet traction motor. This case provides experimental information of the behavior of the DLC of the windings. The prototype motor equipped with DLC windings is installed in an electric bus so that typical bus load cycles can be tested.

Power management system for a fuel cell/battery hybrid vehicle incorporating fuel cell and battery degradation

Optimization of fuel cell/battery hybrid vehicle systems has primarily focused on reducing fuel consumption. However, it is also necessary to focus on fuel cell and battery durability as inadequate lifespan is still a major barrier to the commercialization of fuel cell vehicles. Here, we introduce a power management strategy which concurrently accounts for fuel consumption as well as fuel cell and battery degradation. Fuel cell degradation is quantified using a simplified electrochemical model which provides an analytical solution for the decay of the electrochemical surface area (ECSA) in the fuel cell by accounting for the performance loss due to transient power load, start/stop cycles, idling and high power load. The results show that the performance loss based on remaining ECSA matches well with test data in the literature. A validated empirical model is used to relate Lithium-ion battery capacity decay to C-rate. Simulations are then conducted using a typical bus drive cycle to optimize the fuel cell/battery hybrid system. We demonstrate that including these degradation models in the objective function can effectively extend the lifetime of the fuel cell at the expense of higher battery capacity decay resulting in a lower average running cost over the lifetime of the vehicle.

Improvement on design and manufacture of bus based on traffic accident prevention

In some typical bus accidents, the causes of passenger injury have presented some common characteristics, which makes it necessary to improve the design of bus. In general, bus traffic accidents can be divided into two typical forms: emergency braking and rollover, both of which could seriously threaten the life security of passengers. In this article, these two kinds of bus accident are studied through numerical simulation and some improving suggestions on bus design and manufacture are given. According to simulation results, passengers may suffer from serious hurt due to emergency braking acceleration and deformation of bus body caused by the impact with highway guardrail. Improving measures include equipping seats with three-point belts, adding board on the handrail and enhancing the material and structure of side uprights of the bus. Simulation results show that these improving measures can provide better protection for the passengers involving bus traffic accidents, which has verified the rationality of these measures.

60-GHz Millimeter-Wave Propagation Inside Bus: Measurement, Modeling, Simulation, and Performance Analysis

Millimeter-wave (mmWave) transmission over the unlicensed 60-GHz spectrum is a potential solution to realize high-speed internet access, even inside mass transit vehicles. The solution involves communication between users and a mmWave-band on-board unit that aggregates/disseminates data streams from/to commuters and maintains the connection with the nearest terrestrial network infrastructure node. In this paper, we provide a measurement-based channel model for the 60-GHz mmWave propagation inside a typical inter-city bus. The model characterizes power delay profile (PDP) of the wireless intra-vehicular channel, and it is derived from about 1000 data sets measured within the bus. The proposed analytical model is further translated into a simple simulation algorithm that generates in-vehicle channel PDPs. Different goodness-of-fit tests confirm that the simulated PDPs are in good agreement with the measured data. Finally, a tapped-delay-line (TDL) channel model is formulated from the proposed PDP model, and the TDL model is used to study the bit error rate (BER) performance of the mmWave link inside bus under varying data rates and link lengths.

Bus Driving Cycle Construct Based on Principal Component Analysis for Lanzhou City

The construction of city bus driving cycle is the key to improve traffic efficiency and transportation capacity. In this paper, the data acquisition parameter model is established by taking the Lanzhou city as an example. The data collected from the vehicle recorder are divided into several kinematics sequences. The eigenvalues of these sequences are investigated by principal component analysis and cluster analysis with SPSS tool. Based on the correlation coefficient of collected data from five typical bus lines for more than one month, three representative kinematic sequences are selected to construct the bus driving cycle for Lanzhou city. Experiments show that: 1) The bus driving cycle for Lanzhou city has the characteristics of less uniform time, low average speed and frequent acceleration and deceleration; 2) There exist large differences in bus driving characteristics between the European ECE15 driving cycle, commonly used in the China's urban roads and that of Lanzhou city.

Analysis of Public Transportation Travel Characteristics of the Elderly based on IC Card Big Data-Taking Qingdao as an Example

Due to technical limit, it is difficult to get the public transportation orient-destination (OD) data in Qingdao. In despite of limited data, the paper introduced a new way to conduct bus passenger flow analysis, taking trip characteristics of the elderly in Qingdao as an example. Based on the analysis of IC card data in various time slots, cluster analysis of typical bus lines, combined with urban population data and person trip survey data, the paper analyzed the passenger bus travel characteristics of the elderly, especially their utilization of public transportation resources.