Since its inauguration in 1988, Hong Kong’s light rail has served as a vital transportation system for Tuen Mun and Yuen Long for over thirty years. While the system may not be glamorous, it is reliable. The real issues lie in insufficient passenger capacity and outdated planning, not in the mode of power.
Yet, there are advocates for a ‘battery light rail’, as if removing overhead cables is a step forward. This notion is both illogical and financially unsound. The primary costs of light rail are land acquisition, planning, and civil engineering, which are already sunk costs and will not be recouped by merely changing the power source. Battery production requires mining, refining, and assembly, inevitably generating carbon emissions; moreover, the land freed up by removing cable poles is long and narrow, making it unlikely to be repurposed for other uses.
Batteries are not lightweight; battery trains will certainly be much heavier than the current ones. Anyone familiar with Newton’s second law knows that to maintain the existing acceleration, one would need to employ more powerful and expensive electric motors. An increase in weight will lead to higher energy consumption. Battery trains will also require regular returns to the depot for charging, meaning they cannot carry passengers while at the depot, necessitating the purchase of additional trains to maintain current service frequencies. If charging is concentrated at night, the depot will need to install high-capacity power supply facilities. All these factors combined mean that the costs will far exceed those of maintaining the existing power supply system. Replacing overhead cables might cost a few hundred million, but fully adopting battery trains could run into tens of billions, resulting in a heavier, more energy-consuming, and harder-to-maintain system—how can this be justified?
In the UK, battery trains are being researched for remote branch lines due to the high costs of adding overhead cables to low bridges and narrow tunnels left over from the Victorian era. Similarly, Germany and Japan only use battery trains to replace diesel trains on non-electrified, low-frequency routes. To dismantle an already established, functional, and reliable power supply system in favor of a heavier and more expensive battery system would likely become an international laughingstock if realized.
Even more absurdly, MTR Corporation recently tested hydrogen-powered light rail, only to discover that the low-floor trains did not match the height of existing platforms, forcing them to halt the project. This issue, which one could easily foresee, required the physical testing of trains to uncover, revealing a shocking lack of understanding of technology by the authorities.
Light rail is not perfect, but its original design was forward-thinking, accommodating wheelchair users, producing zero emissions, and providing deep community routes to serve residents for decades. What needs to be done today is to enhance passenger capacity and improve the passenger experience, rather than waste public funds on futile experiments that squander time.
Misdiagnosing the problem will render all efforts futile. What light rail needs is pragmatic reform, not a doomed dream of battery power.
