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

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.