Is it a bus? Is it a train? Notes on modal etymology and nomenclature

05 Mar 2018

Yale Wong

London has the tube, New York has the subway and Paris has the metro. Each name carries deep historical connotations which have since transcended their original meaning and evolved to become generic terms for urban passenger heavy rail transport. The London Underground (nicknamed Tube) gets its name from its circular, deep-level bored tunnels1. The term subway, predominantly used in the Americas (and also Glasgow and some Asian cities) is also derived from underground lines in the city core2. Many cities, however, including Australia and most Commonwealth nations have adopted the metro nomenclature which is common across multiple European languages.

The term metro is derived from the Paris Metropolitan (Compagnie du chemin de fer métropolitain), which (despite some protest reflecting cross-channel rivalry!) was itself based off London’s Metropolitan Railway—the world’s first underground railway opening some 40 years earlier in 1863. The term metro carries such positive connotations that its use has been extended to cover commuter rail systems (e.g., Melbourne3), light rail systems (Canberra) and even bus services (Tasmania). This overuse (or abuse) of the term raises the question as to whether metro ought to continue carry its implied modal meaning.

In their original sense, metro/subway/tube carry an underground implication which exists not only in phonogramic languages like English but also logogramic Chinese languages and derivatives (i.e., Japanese, Korean, Vietnamese). New high speed metro lines (e.g., Shanghai Metro Line 16, Shenzhen Metro Line 11) and interurban metros best distinguished by their operating speeds, station spacing and line length are also popping up in sprawling Chinese cities which transcend the English metro definition in other ways (making the oft-criticised operating characteristics of Sydney Metro Northwest look tame in comparison). This same ambiguity can also be extended to various other forms of rail and road-based urban public transport.

A separate conversation concerns the features of light and heavy rail (and by extension, trams). A major level of ambiguity arises from the essential misuse of terminology. The term light rail has been applied in all sorts of circumstances—think everything from London (the metro-esque Docklands Light Railway), to the Stockholm Roslagsbanan (closer to commuter rail), Singapore (an elevated people mover) and Melbourne (trams running on former heavy rail corridors). In China, light rail is usually used to describe medium capacity metros and also high capacity monorails (e.g., Chongqing).

The reality is that the light and heavy rail distinction is based entirely on axle weights. We have since transcended this engineering definition to more user-based standards which offer greater comprehendability and is in itself not a major issue until used to misinform. There does exist also a range of tram-train systems (particularly in Germany) which complicates this comparison as well as bus-bodied trains in different incarnations (e.g., Pacers in the UK and dual-mode vehicles in Hokkaido, Japan)?

The humble bus has long been associated with many negative connotations (e.g., noisy, slow, complicated to navigate). The bus rapid transit versus light rail transit debate4 is one of great emotion and ideology and there has been much research on the choice versus blind commitmenta dichotomy (coined by Professor David Hensher) exhibited by political leaders. To take advantage of people’s preferences (whether founded or not5), there is increasing interest in branded bus services (e.g., Sydney’s recently opened B-Line) and buses which emulate the look and feel of a tram as more affordable alternatives to giving buses that image upgrade.

Various guidance technologies are further blurring the divide between bus and rail. Rubber-tyred metro systems, for instance, offer better traction and acceleration (especially at grade) on many urban rail systems. Kerb guided buses (e.g., Leeds, Adelaide O-Bahn) have been around for some time (though many would argue a gimmick only). Magnetic guidance systems have had various incarnations too, as well as optically guided buses—in Rouen, France and Castellón, Spain as examples, but recently gaining new attention through the “trackless train” marketed by China’s CRRC and trialled in Zhuzhou. Do these modes operating on virtual tracks qualify as trains and is there an intention to mislead? Increasingly, there is a convergence of modes and so we are invited to ask exactly what constitutes a bus and what constitutes a train.

Ultimately, each mode label is a categorical term with no fine boundary. The blur showcases how language evolves (and used to the advantage of decision-makers) with implications (for instance) on transport research such as the design of choice experiments. Clearly, these elements play out through an individual’s experiences with various systems in different countries (consciously or otherwise) as we try to discern mode choice or an individual’s preferences for a particular mode (e.g., willingness-to-pay). Naturally, each transport mode (and the mode label itself!) constitutes a bundle of attributes (on technology, right-of-way, etc.) that if left undefined, allows the respondent to make their own judgement which is captured through a larger error term in the modelling.

Mode labels are applied so inconsistently (for political and other purposes) that they often communicate little about the essential characteristics of transport service–i.e., frequency and span. Whilst these labels constitute a useful starting point, there is a need for mode-agnostic thinking and to base transport policy on service characteristics rather than motive technology. We cannot let language cloud our judgement and need to be aware of the potential use, misuse and abuse of mode labels.

This paper contributes to the research program of the Volvo Research and Education Foundation Bus Rapid Transit Centre of Excellence.

  1. The earliest tunnels, however, were not circular—built using cut-and-cover methods at the sub-surface level.
  2. Other local terms have also emerged in the US like the L (Chicago) and the T (Boston)
  3. Urban heavy rail in Australia can more accurately be described as commuter/suburban rail (though increasingly with metro elements)
  4. Whilst this is true in the developed world, it is a minibus taxi versus bus rapid transit formalisation debate that takes hold in developing countries (i.e., in Africa, South America and parts of Asia)
  5. Most operating attributes like punctuality and reliability are a result of right-of-way rather than traction technology (i.e., road or rail)