Toronto has the only existing street railway/"light rail" gauge in Ontario.

Track gauge is a finer detail in the technology of rail-based transportation.  It is defined as the distance between the inside edges of the heads of the running rails.  It’s an important detail since this decides the distance between wheels on the trucks/bogies of rail cars, which can impact what systems on which said rail cars can and cannot run.

What makes this topic interesting in Toronto and the GTA is that the TTC has its own unique gauge: 1495mm.  This applies to both the streetcar and the subway networks of the TTC, but excludes the SRT (which is currently standard gauge. However, if the SRT is converted to LRT, as is widely expected, it would be changed to TTC gauge).  The TTC is expected to apply their unique gauge to Transit City as well, as it keeps the system flexible and has maintenance efficiencies.

Standard gauge, however, is 1435mm, and is used by the freight railways, which would include GO Transit’s rail fleet.  If one goes back in Toronto’s history, one will find two streetcar companies operating on Toronto’s streets, one at standard gauge and the other at the TTC’s, a result of meeting a legal requirement at the time.

There are now many communities in Ontario talking about LRT in their future networks.  These include not only Toronto, but also Hamilton, York Region, Region of Peel, Kitchener-Waterloo, Ottawa, and even London. (more…)