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

Untersuchung der Auswirkungen der Elektrifizierung und Automatisierung des öffentlichen Busverkehrs auf die Nachhaltigkeit – Eine Fallstudie in Singapur

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Abstract

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.

Zusammenfassung

Elektrifizierung und Automatisierung stoßen im öffentlichen Verkehr auf Interesse aufgrund ihres Potenzials zur Verbesserung der Energieeffizienz, Kosteneffizienz und Umweltverträglichkeit. Bis zum Jahr 2030 plant Singapur, autonome Busse/Kleinbusse in das vorhandene Verkehrssystem zu integrieren. Vor dem landesweiten Einsatz autonomer Fahrzeuge müssen jedoch deren Auswirkungen auf die Nachhaltigkeit evaluiert werden. Hierfür wurde in Singapur eine Studie durchgeführt, um die Kosten und Umweltauswirkungen autonomer elektrischer Kleinbusse zu bewerten. Die Ergebnisse dieser Studie werden in dieser Veröffentlichung vorgestellt und diskutiert. Es wird eine Fallstudie gezeigt, um die Auswirkungen des Ersatzes von Dieselbussen mit menschlichen Fahrern durch elektrifizierte und automatisierte Kleinbusse auf die Lebenszykluskosten und die Treibhausgasemissionen auf sieben verschiedenen Strecken zu demonstrieren. Die untersuchten Fahrzeuge waren ein 12-m-Dieselbus mit menschlichem Fahrer, ein elektrifizierter 6‑m-Kleinbus mit menschlichem Fahrer und ein elektrifizierter autonomer 6‑m-Kleinbus. Zunächst wurden die Auswirkungen der Fahrzeugkonzepte auf die Fahrpläne analysiert, um die Betriebsstrategie und die Passagierbelegung entlang der Strecken zu ermitteln. Anschließend wurden eine Lebenszyklusanalyse („Life Cycle Assessment“, LCA) und eine Lebenszykluskostenbetrachtung („Total Cost of Ownership“, TCO) durchgeführt, um die Kosten sowie die Treibhausgasemissionen jeweils auf Flottenebene zu vergleichen. Die Ergebnisse zeigen eine Reduzierung der Gesamtlebenszykluskosten für den autonomen elektrischen Kleinbus um 43 % im Vergleich zum 12-m-Dieselbus. Die Treibhausgasemissionen während des gesamten Lebenszyklus des autonomen 6‑m-Kleinbusses wurden im Vergleich zum 12-m-Dieselbus ebenfalls um 47 % reduziert, obwohl bei ersterem mehr Fahrzeuge in der Flotte benötigt wurden.

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Notes

  1. Land Transport Authority (LTA), Personal Communication, 2017.

  2. Land Transport Authority, “Fuel consumption of single-deck buses”, Personal Communication, 2017

  3. Land Transport Authority (LTA), Personal Communication, 2017.

  4. Land Transport Authority (LTA), Personal Communication, 2017.

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Acknowledgements

The research was conducted under the Campus for Research Excellence and Technological Enterprise (CREATE) with financial support of the Singapore National Research Foundation (NRF).

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Authors and Affiliations

  1. 1 Create Way, #10-02 CREATE Tower, TUMCREATE Limited, Singapore, Singapore

    Aditya Pathak, Ganesh Sethuraman & Aybike Ongel

  2. Institute of Automotive Technology, Technical University of Munich, Garching, Germany

    Markus Lienkamp

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  1. Aditya Pathak
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  2. Ganesh Sethuraman
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  3. Aybike Ongel
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  4. Markus Lienkamp
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Contributions

Aditya Pathak predominantly accomplished the conceptualization, methodology, and simulations. Ganesh Sethuraman mainly accomplished data curation, formal analysis, and validation. The first two authors contributed equally to this work. Aybike Ongel is the principal investigator of the project contributed to the overall concept and proofreading of the manuscript. Markus Lienkamp revised the paper critically for intellectual content and agreed to all aspects of the work. As a guarantor, he accepts responsibility for the conceptual integrity of the paper.

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Correspondence to Ganesh Sethuraman.

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Pathak, A., Sethuraman, G., Ongel, A. et al. Impacts of electrification & automation of public bus transportation on sustainability—A case study in Singapore. Forsch Ingenieurwes 85, 431–442 (2021). https://doi.org/10.1007/s10010-020-00408-z

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