In all the debates about transit options, be they in Scarborough or elsewhere, one of the most abused and frequently misunderstood terms is “LRT”.

The term appears in various contexts over the years under both the guise “Light Rail Transit” and “Light Rapid Transit”.  The difference can be more in local preference including marketing aims.

One can even find “LRRT” where a proposal tries to be all things to be all people.  The Buffalo line, which incongruously runs on the surface downtown, but in a tunnel elsewhere, originally used this term, but was rebranded “Metro Rail”.  The “LRRT” term, however, is still in current use as a Google search will demonstrate.

The term “Light” contrasts “LRT” with systems that require more substantial (or “heavy”) infrastructure such as:

• mainline railways including commuter rail operations such as GO,
• “subways” as the term is used in Toronto (with other words such as “Metro” and “Tube” found in other cities),
• any technology requiring a dedicated, segregated guideway and stations either because of automated control systems or because the right-of-way cannot be crossed for various reasons.

Life gets very confusing because there are overlaps between technologies and their implementation.  One of the oldest streetcar systems in North America, Boston’s, exhibits every conceivable type of operation with the same vehicles running in mixed traffic (little of this remains on the network), on reserved lanes in street medians, on private rights-of-way that run “cross country” relative to the road network, on elevated structures, and in tunnels just like a subway.  (The “Blue Line” running under the Boston harbour was originally a streetcar tunnel, but was converted to “subway” operation in the 1920s.)

The Boston Green Line is the oldest subway on the continent, and it runs with “streetcars” that morph into “light rail vehicles” not because of magic performed where they leave the street pavement, but because of the way the vehicles are used.  This is central to the concept of “LRT” – the ability to operate in many environments as appropriate to demand and local circumstance.

Unlike what Toronto calls a “subway”, an LRT network can adapt to its surroundings and this is a fundamental characteristic of the mode.  The original Scarborough LRT would have run at grade with some road crossings enroute, and a Malvern extension was on the books, but never built.

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