ArticlePublisher preview available

Impacts of electrification & automation of public bus transportation on sustainability—A case study in Singapore

Authors:
Aditya Pathak at TUMCREATE
Aditya Pathak
  • TUMCREATE
Ganesh Sethuraman at Technical University of Munich
Ganesh Sethuraman
Aybike Ongel at Bern University of Applied Sciences
Aybike Ongel
Markus Lienkamp at Technical University of Munich
Markus Lienkamp
Read publisher preview
Download citation
To read the full-text of this research, you can request a copy directly from the authors.

Abstract and Figures

Electrification and automation are attracting interest from the public-transportation sector for their potential to improve energy efficiency, cost efficiency, and environmental performance. Singapore is planning to integrate autonomous buses/minibuses into its transportation system by 2030. However, before the island-wide deployment of autonomous vehicles, there is a need to evaluate their effects on sustainability. A study was therefore conducted in Singapore to evaluate the costs and environmental impacts of autonomous electric minibuses, and the results are revealed and discussed here. This paper presents a case study to demonstrate the impacts of replacing human-driven diesel buses with electrified and automated minibuses on life-cycle costs and greenhouse gas (GHG) emissions for seven routes. The vehicles evaluated were a 12‑m human-driven diesel bus, a 6‑m electrified human-driven minibus, and a 6‑m electrified autonomous minibus. First, the impacts of the vehicle concepts on the scheduling were analysed to obtain the operational strategy and passenger occupancy along the route. A life-cycle assessment (LCA) and a total cost of ownership (TCO) analysis were then conducted to compare the fleet-level costs and GHG emissions. The results showed a 43% reduction in total life-cycle cost for the autonomous electric minibus, compared with the 12‑m diesel bus. The life-cycle GHG emissions of the 6‑m autonomous electric minibus were also reduced by 47% compared with the 12‑m diesel bus, despite the fact that a larger number of the former vehicle were required in the fleet.
Figures - available from: Forschung im Ingenieurwesen
This content is subject to copyright. Terms and conditions apply.
A preview of this full-text is provided by Springer Nature.
Learn more
Content available from Forschung im Ingenieurwesen
This content is subject to copyright. Terms and conditions apply.
ORIGINALARBEITEN/ORIGINALS
https://doi.org/10.1007/s10010-020-00408-z
Forsch Ingenieurwes (2021) 85:431–442
Impacts of electrification & automation of public bus transportation on
sustainability—A case study in Singapore
Aditya Pathak1· Ganesh Sethuraman1·AybikeOngel
1· Markus Lienkamp2
Received: 14 January 2020 / Published online: 6 July 2020
© Springer-Verlag GmbH Deutschland, ein Teil von Springer Nature 2020
Abstract
Electrification and automation are attracting interest from the public-transportation sector for their potential to im-
prove energy efficiency, cost efficiency, and environmental performance. Singapore is planning to integrate autonomous
buses/minibuses into its transportation system by 2030. However, before the island-wide deployment of autonomous vehi-
cles, there is a need to evaluate their effects on sustainability. A study was therefore conducted in Singapore to evaluate
the costs and environmental impacts of autonomous electric minibuses, and the results are revealed and discussed here.
This paper presents a case study to demonstrate the impacts of replacing human-driven diesel buses with electrified and
automated minibuses on life-cycle costs and greenhouse gas (GHG) emissions for seven routes. The vehicles evaluated
were a 12-m human-driven diesel bus, a 6-m electrified human-driven minibus, and a 6-m electrified autonomous minibus.
First, the impacts of the vehicle concepts on the scheduling were analysed to obtain the operational strategy and passen-
ger occupancy along the route. A life-cycle assessment (LCA) and a total cost of ownership (TCO) analysis were then
conducted to compare the fleet-level costs and GHG emissions. The results showed a 43% reduction in total life-cycle
cost for the autonomous electric minibus, compared with the 12-m diesel bus. The life-cycle GHG emissions of the 6-m
autonomous electric minibus were also reduced by 47% compared with the 12-m diesel bus, despite the fact that a larger
number of the former vehicle were required in the fleet.
Ganesh Sethuraman
ganesh.sethuraman@tum-create.edu.sg
11 Create Way, #10-02 CREATE Tower, TUMCREATE
Limited, Singapore, Singapore
2Institute of Automotive Technology, Technical University of
Munich, Garching, Germany
K
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... In another study, Zhang (2020) investigates the environmental impact of autonomous buses, revealing reduced emissions and energy usage. The Singapore-based research evaluates autonomous electric minibuses, showing a significant 43% cost reduction and a remarkable 47% decrease in life-cycle greenhouse gas emissions compared to diesel buses, emphasizing their potential as a sustainable transportation solution (Pathak, 2021). The utilization of dedicated managed lanes further enhances these benefits, especially for bus emissions and energy consumption. ...
Implications of Autonomous Buses on Public Transit Systems: A Literature Review
Article
Full-text available
  • Mar 2025
In the age of rapid technological progress, the emergence of autonomous buses is reshaping public transportation. Powered by cutting-edge technologies, these buses signify a future marked by intelligent, secure, and eco-friendly urban mobility. This study employs VOSviewer for bibliometric analysis, focusing on the functional aspects of autonomous bus studies published between 2018 and 2024. The findings reveal that 58% of the studies originate from outside of Europe and the United States. The analysis highlights four key categories: Operational Efficiency, Safety and Compliance, Sustainability and Emission, and Passenger Experience. While cost reductions are expected, the feasibility of autonomous buses as a competitive option varies. Despite potential financial benefits from eliminating driver-related costs, concerns about user acceptance and safety advocate for personnel presence. This review highlights the need for further research in network design, vehicle resizing, and environmental impacts, offering insights into the complexities of integrating autonomous buses into public transit systems.
View
... To address such challenges, several alternatives can be considered in the BRT operation, such as vehicle electrification and automation [4]. The incorporation of vehicle electrification and automation into public transportation systems would be anticipated to reduce operational costs, such as fuel prices and labour costs [5][6][7]. Previous research has been conducted to investigate the effects of implementing electric-based public transit bus fleets on energy consumption, considering factors such as passenger load, average speed, and service time [8]. The findings suggest that the electrification of bus fleets would yield considerable energy savings, given that the average energy efficiency of battery electric buses surpasses that of conventional diesel buses. ...
Risk‐based maximum speed advisory system for driving safety of connected and automated bus
Article
Full-text available
Bus rapid transit (BRT) system is a cost‐effective way to provide public transportation service. However, it faces some challenges such as reduced labour productivity and increasing fuel costs. One solution is introducing automated vehicles (AV) to reduce operational expenses. However, there are still limitations on completely replacing human drivers even in limited operational design domains (ODD). Furthermore, AVs often suffer from poor driving stability in some roadways, such as abrupt changes in road geometry. To enhance the driving safety of AV‐based BRT services, this study develops a new connected and automated bus (CAB) system using a cloud‐based traffic management centre with cooperative intelligent transportation systems. The proposed system introduces risk‐based maximum speed advisory system (RMSAS), which controls the maximum advisory speed of CAB to reduce its driving risk. This research evaluates the performance of RMSAS by comparing it to other driving modes, such as human‐driven vehicles and conventional AVs, based on real‐world field operational tests. The result shows that the proposed system outperforms other driving modes in terms of driving risks, particularly in some road geometry‐related ODDs. Hence, this research concludes that the proposed system can be applied to the AV‐based BRT service for uprating its safety performance.
View
... The bus purchase price without batteries is $315,320. The battery price for an e-bus can range from $137/kWh to $700/ kWh (BloombergNEF, 2020;Pathak et al., 2021;Statusrapport, 2020;Zeng et al., 2022). We use $300/kWh as the default battery price and present a supplemental sensitivity analysis for prices ranging from $100/kWh to $700/kWh in Section 5.2. ...
View
... Not only for cars and lorries but also for buses, a microsimulation has shown that autonomous buses are expected to save 27.2% in CO2 emissions compared to today's buses used in local public transport (Hasan et al., 2022). A study in Singapore even demonstrated a 47% reduction in greenhouse gas emissions over the entire life cycle of autonomous electric minibuses compared to diesel buses (Pathak et al., 2021). The emissions reductions are also reflected in the logistics networks of the food industry. ...
Influences of Autonomous Vehicles on Sustainability: A Systematic Literature Review
Chapter
  • Jan 2024
Autonomous driving is an attractive and controversial topic in the field of mobility research. With the continuous technical progress in the field of autonomous vehicles, scientific research in this area is also growing exponentially. This is equally true for the topic of sustainability. Here, too, research interest and the resulting scientific publications have increased significantly in recent years. From the two mutually reinforcing factors, the risk of information overload for researchers can be derived. This paper attempts to address this complex of issues in a systematic manner. To this end, previous research is examined using a systematic literature review. Bibliometric methods and a qualitative content analysis support this approach. This summary is intended to serve as a basis for further research. This includes summarising current research as well as identifying current research gaps. The results of the article show a growing field of research with many special features. Above all, reducing emissions and increasing efficiency are decisive contributions to the sustainability of autonomous vehicles.
View
... Vehicle stock and CO 2 emissions are published by ACEA and EEA [2,5], respectively. The mileage stated for buses is based on data from the German Ministry of Digital and Transport [7], consumption according to Pathak et al. [8]. account, trucks are responsible for 25 % of the European road-related energy consumption and, consequently, 7 % of total European greenhouse gas emissions [2,6]. ...
View
View
Rebound effects undermine carbon footprint reduction potential of autonomous electric vehicles
Article
Full-text available
  • Oct 2023
Autonomous vehicles offer greater passenger convenience and improved fuel efficiency. However, they are likely to increase road transport activity and life cycle greenhouse emissions, due to several rebound effects. In this study, we investigate tradeoffs between improved fuel economy and rebound effects from a life-cycle perspective. Our results show that autonomy introduces an average 21.2% decrease in operation phase emissions due to improved fuel economy while manufacturing phase emissions can surge up to 40%. Recycling efforts can offset this increase, cutting emissions by 6.65 tons of Carbon dioxide equivalent per vehicle. However, when examining the entire life cycle, autonomous electric vehicles might emit 8% more greenhouse gas emissions on average compared to nonautonomous electric vehicles. To address this, we suggest; (1) cleaner and more efficient manufacturing technologies, (2) ongoing fuel efficiency improvements in autonomous driving; (3) renewable energy adoption for charging, and (4) circular economy initiatives targeting the complete life cycle.
View
View
FAMU-FSU COLLEGE OF ENGINEERING DEVELOPMENT OF A DISCRETE EVENT SIMULATION MODEL FOR THE BUS SYSTEM AT THE FAMU-FSU COLLEGE OF ENGINEERING
Thesis
Full-text available
  • Dec 2022
Mobility and access are the two essential criteria for evaluating any mode of transportation. A private vehicle comes at the top when we think about mobility and access. But an increase in the utilization of private vehicles has many drawbacks, such as an increase in traffic congestion, air pollution, fuel consumption, etc., which also affect public health. It is essential to provide an efficient public transportation system to minimize these effects, especially in urban areas. Bus transportation is one of the significant modes of transport with a good capacity compared to private vehicles, but there is a need to compromise for access. Bus transportation is an essential mode of transportation for students, faculty, and staff, especially to travel to, around, and from school and work. It is always necessary that buses reach the stop on time and service all the passengers waiting at the stop, considering peak hour demands and potential uncertainties in transportation time. To achieve such an objective, it is essential to improve the serviceability of the bus transportation network. This study focuses on improving the operations of the Florida State University (FSU) campus bus service, Seminole Express, for the “INNOVATION” bus route in Tallahassee, Florida (USA). The “INNOVATION” bus route service connects the main FSU campus with the FAMU-FSU College of Engineering and is heavily used by the FSU students. A simulation model is built using the FlexSim simulation software to emulate the operations of the “INNOVATION” bus route service to determine the required number of buses to be deployed. An excessive number of buses may increase the operational costs and idling time. In the meantime, an insufficient number of buses will cause significant waiting times at the bus stop, which are not desirable as some students may be late for their classes. The developed simulation model will assist with effectively planning the bus route connecting the main FSU campus with the FAMU-FSU College of Engineering by providing solutions with adequate waiting time and operational costs
View
Requirement Analysis of Fast-Charging Stations
Chapter
  • Aug 2022
In order to discuss the design and operation aspects of a fast-charging station, it is essential to understand the requirements that will be used to design high-performance fast-charging station (FCS). This chapter presents requirements analysis for all functions of FCS, which are classified as follows: FCS design, FCS facility, energy management, and charging units. The chapter explained possible requirements for each category and associated performance targets and implementation strategies. Best practices are covered in three regions: the United States, Europe, and Asia. Related standards are explained and used to analyze requirement analysis. Functional modeling is used to demonstrate the understanding of FCS and map to design requirements. Analysis of mobility is used to plan the deployment of fast-charging infrastructures.
View
View
Electric buses’ sustainability effects, noise, energy use, and costs
Article
Full-text available
  • Sep 2019
Electric buses are growing in numbers in Sweden, which contributes to the development of a fossil fuel free society and a reduction of emissions. Earlier studies of bus systems have identified a need to further investigate societal costs, total cost of ownership, energy use on a yearly basis to account for seasonal variations, and noise during acceleration. Addressing those needs was the purpose of this study. Investigations were made in five cities in Sweden that have recently implemented different electric buses in their respective public transport system. Based on results from these investigations and earlier studies, new and developed models where designed and applied on electric buses on route 1 in Karlskrona, as a representative example. It was found that there were significant savings in societal costs and total cost of ownership when compared to diesel and biogas powered buses, mainly due to decreased noise, no emissions in the use phase, and decreased energy use.
View
Exploration of Optimal Powertrain Design Using Realistic Load Profiles
Article
Full-text available
  • Sep 2019
The electrification of bus-based public transportation contributes to the goal of reducing the adverse environmental impacts caused by urban transportation. However, the penetration of electric vehicles has been slow due to their lower vehicle range and total costs in comparison to vehicles driven by internal combustion engines. By improving the powertrain efficiency, the total costs can be reduced for the same vehicle range. Therefore, this paper proposes a holistic design exploration approach to investigate and identify the optimal powertrain concept for electric city buses based on the component costs and energy consumption costs. The load profiles of speed, slope, and passenger occupancy profiles are derived for a selected bus route in Singapore, which is used in a powertrain design exploration for a 30-passenger vehicle. Six different powertrain architectures are analyzed, together with single and multi-speed gearbox configurations, to identify the optimal powertrain architecture and the resulting component sizes. The powertrain configurations are further analyzed in terms of their influence on the vehicle characteristics and total costs. Multi-motor configurations were found to have better vehicle characteristics and lower total costs in comparison to single rear motor configurations. Concepts with motors on the front and a rear axle could shift the load points to a higher efficiency region, resulting in lower energy consumption and energy costs. The optimal powertrain concept was a fixed-speed two-motor configuration, with a booster motor on the front axle and a motor on the rear axle.
View
Simulation-based assessment of the energy demand in battery cell manufacturing
Article
Full-text available
  • Jan 2019
Electric vehicles are seen as a solution towards mitigating the environmental impacts of the transportation sector as they do not produce tailpipe emissions. However, this technological shift in the transportation sector brings new environmental challenges. Particularly, the production of the battery system has been estimated to potentially contribute to around 50% of the total cradle to gate environmental impact of the production of an electric vehicle. In this regard, the energy required for the manufacturing of battery cells has been identified as one of the largest environmental and economic hotspots. While the emerging battery manufacturing industry is still highly unconstrained, the variability of product and processing parameters is difficult to capture and compare. Even more, battery cell manufacturing consists of a complex and dynamic combination of numerous continuous and discrete processes as well as technical building services which account for a high share on energy demand. This has led to a large uncertainty in the values reported in the current literature and also hinders the derivation of improvement measures. Against this background, the paper presents a simulation-based assessment of the energy demand in battery cell manufacturing. Based on collected field data, a multi-paradigm simulation of the battery manufacturing process chain has been built. Multiple simulations scenarios were subsequently run allowing to analyze the factors and circumstances driving energy demand. This paper aims to contribute towards enhancing the knowledge on the energy related impacts of traction battery systems and to provide a frame of reference for the variability of the required manufacturing energy that might be used as input for further sensitivity analysis in system assessment methodologies such as Life Cycle Assessment (LCA) or Life Cycle Costing (LCC) respectively Total Cost of Ownership (TCO).
View
Economic Assessment of Autonomous Electric Microtransit Vehicles
Article
Full-text available
  • Jan 2019
There is rapidly growing interest in autonomous electric vehicles due to their potential in improving safety, accessibility, and environmental outcomes. However, their market penetration rate is dependent on costs. Use of autonomous electric vehicles for shared-use mobility may improve their cost competitiveness. So far, most of the research has focused on the cost impact of autonomy on taxis and ridesourcing services. Singapore is planning for island-wide deployment of autonomous vehicles for both scheduled and on-demand services as part of their transit system in the year 2030. TUMCREATE developed an autonomous electric vehicle concept, a microtransit vehicle with 30-passenger capacity, which can complement the existing bus transit system. This study aims to determine the cost of autonomous electric microtransit vehicles and compare them to those of buses. A total cost of ownership (TCO) approach was used to compare the lifecycle costs. It was shown that although the acquisition costs of autonomous electric vehicles are higher than those of their conventional counterparts, they can reduce the TCO per passenger-km up to 75% and 60% compared to their conventional counterparts and buses, respectively.
View
State of the Art of Automated Buses
Article
Full-text available
  • Aug 2018
Urban transportation in the next few decades will shift worldwide toward electrification and automation, with the final aim of increasing energy efficiency and safety for passengers. Such a big change requires strong collaboration and efforts among public administration, research and stakeholders in developing, testing and promoting these technologies in public transportation. Working in this direction, this work provides a review of the impact of the introduction of driverless electric minibuses, for the first and last mile transportation, in public service. More specifically, this paper covers the state of the art in terms of technological background for automation, energy efficiency via electrification and the current state of the legal framework in Europe with a focus on the Baltic Sea Region.
View
Dynamic Autonomous Road Transit (DART) For Use-case Capacity More Than Bus
Article
Full-text available
  • Nov 2019
The Dynamic Autonomous Road Transit (DART) is a novel concept for developing a smart public transportation (PT) system. It is currently under progress at TUMCREATE Singapore. The city-state of Singapore is known for optimizing its limited land resources and maintaining a flourishing balance between society, economy and environment by planning well in advance for the future. In the view of scarcity of land and increasing population, travel demand and construction costs, the city further aims to have sophisticated PT systems without expanding its already significantly vast road infrastructure. The DART system as a new PT solution seeks to bridge the existing capacity gap between the existing Mass Rapid Transit (MRT) and Bus systems featuring fully autonomous vehicle modules integrated within a hi-tech, sustainable and efficient system design. This paper discusses the DART concept followed by more detailed explanation about its use-case: capacity more than bus. For this use-case, the DART network planning and the two key features of this system: platooning and virtual right of way are presented.
View
Cost-based analysis of autonomous mobility services
Article
Full-text available
  • Oct 2017
  • TRANSPORT POLICY
Fast advances in autonomous driving technology trigger the question of suitable operational models for future autonomous vehicles. A key determinant of such operational models’ viability is the competitiveness of their cost structures. Using a comprehensive analysis of the respective cost structures, this research shows that public transportation (in its current form) will only remain economically competitive where demand can be bundled to larger units. In particular, this applies to dense urban areas, where public transportation can be offered at lower prices than autonomous taxis (even if pooled) and private cars. Wherever substantial bundling is not possible, shared and pooled vehicles serve travel demand more efficiently. Yet, in contrast to current wisdom, shared fleets may not be the most efficient alternative. Higher costs and more effort for vehicle cleaning could change the equation. Moreover, the results suggest that a substantial share of vehicles may remain in private possession and use due to their low variable costs. Even more than today, high fixed costs of private vehicles will continue to be accepted, given the various benefits of a private mobility robot.
View
Development of an Overall Vehicle Sizing and Packaging Tool for Autonomous Electric Buses in the Early Concept Phase
Article
  • Mar 2020
The demand for autonomous electric public transport is increasing globally. The operational requirement of these autonomous vehicles differs widely. Hence, there is an increase in the demand for different vehicle sizes and configurations. This has led to a number of methods and improvements in the vehicle package development process. This article presents the development of a holistic parametric packaging tool for autonomous vehicles called Autonomous Electric Vehicle Tool (AEV tool). The tool is designed with MATLAB, and via a Graphical User Interface (GUI), the user can input parameter data, which directly adjusts a parametric Computer-Aided Design (CAD) model developed with CATIA software. The overall vehicle dimensions, as well as the size of single components, can be changed, and different topology configurations can be chosen. Moreover, it is possible to visualize the CAD models compare them with each other according to the vehicle’s specifications, such as the external dimensions and weight. The tool is able to develop vehicle concepts for 4 m to 12 m long autonomous electric buses. The developed tool is validated with respect to two autonomous electric buses and ten electric buses. The weight distribution of the major subsystems for different vehicle concepts is analyzed as well. The validation results confirm the accuracy of the assessed weight of the generated concept buses.
View
Joint Optimization of Vehicle Battery Pack Capacity and Charging Infrastructure for Electrified Public Bus Systems
Article
  • Aug 2019
Although electric buses operate at lower noise levels and without direct emissions, only a small fraction of bus fleets in the world is electrified due to the high investment associated with the battery systems of the electric vehicles and the required charging infrastructure. To make the cost of electrification more competitive, the design of the battery pack and the charging infrastructure should be optimized for the specific operating conditions. In this paper, a method is presented that minimizes the total cost of ownership of the electric bus fleet by choosing the optimal battery size, number of charging stations, and charging power for a given schedule, vehicle characteristics and environmental conditions. The method serves as a decisionmaking aid for automotive engineers in the early vehicle design process and/or for urban transit agencies to select appropriate vehicle models. Implementation of the method in a case study showed that the optimization can reduce the costs that are influenced by the battery and charging infrastructure by 22.8%, compared to the reference vehicle and the charging configuration of the pilot project. This is mainly attributed to the reduced battery pack capacity and the higher utilization ratio of the charging infrastructure.
View