The issue begins with the name. Taiwan refers to it as the “MRT,” while mainland China calls it “rail transit,” succinctly conveying the system’s nature. In contrast, Hong Kong’s “Smart Green Public Transport System” comprises ten characters and still lacks a concise, catchy, and recognizable name in Chinese. Although official documents use the English abbreviation SGMTS, this acronym is hardly known among the public; most citizens have neither heard of it nor can they immediately grasp what it refers to. In everyday discussions, people still rely on place names or old terms as substitutes. This is not merely a matter of linguistic habit but a failure in policy communication: if a public transport system cannot naturally enter everyday language, it reflects a vague positioning from the outset.
Setting aside the naming issue, let us return to the engineering reality. Whether it is the cloud bus or the smart rail, both have not escaped the fundamental requirements of heavy civil engineering. Dedicated right-of-way, roadbed, and bridge piers are often still indispensable. The so-called innovation mainly lies in not using steel tracks, opting instead for rubber wheels or guided systems. However, the absence of steel tracks complicates the distribution of loads over long distances, limits axle loads, makes it difficult to extend carriages, and hinders the increase of service frequency. The capacity ceiling is locked in at the design stage; to catch up with light rail standards, higher specifications for right-of-way isolation and signaling systems would be necessary, which would, in turn, negate the original rationale for their existence.
The problems posed by rubber wheels extend far beyond capacity. Firstly, there is pollution. Tire wear releases a significant amount of micro-particles, which are a major non-exhaust pollutant in urban air; steel wheels on steel tracks can almost be ignored in this regard. Secondly, there are costs. Rubber wheels wear out quickly and require frequent replacement, which not only increases material and labor costs but also raises the frequency of downtime and maintenance, thereby elevating the lifecycle costs of the entire system over the long term. These are not hypothetical calculations but realities that have repeatedly emerged in several cities after years of operation.
Some argue that rubber wheels have a traction advantage on steep gradients. This is valid but applies only to a few specific terrains. If the route is primarily flat, the higher rolling resistance of rubber wheels will only lead to greater energy consumption and faster wear, without any compensatory performance benefits, while imposing an additional burden on the entire system over the years.
As for replacing overhead cables or the third rail with batteries, this seems fundamentally misguided. Public transport with fixed routes is ideally suited for centralized power supply. Carrying energy onboard for extended periods leads to aging over time and increases vehicle weight, directly compressing passenger capacity. In each journey, part of the energy is merely used to propel the battery itself, naturally reducing efficiency. This is not a transitional stopgap but a design choice that complicates an already mature problem.
What is truly alarming is the inversion of the entire narrative direction. The essence of public transport has never been about looking “new”; rather, it is about whether it can reliably, abundantly, and sustainably transport passengers in high-density urban areas. If a proposal cannot demonstrate clear advantages in capacity, efficiency, and cost, relying instead on adjectives like “smart” and “green” to hold its ground, it resembles a policy narrative rather than an engineering solution.
When a system cannot be succinctly described in one or two words, fails to allow citizens to intuitively understand “how it is better than existing options,” and even technically compromises in many areas, the problem is not merely a selection error but a deviation in decision-making logic itself. Public transport is not a stage for showcasing creativity; it is the foundation upon which a city can function normally. If that foundation relies on packaging for support, it will inevitably reveal structural voids.
