Very long tramsets (over 60 metres in some cases) are awkward to accommodate in cities with short blocks. A second tramset cannot begin to enter a short block until it is certain that the tramset in front will move.
https://www.aptnsw.org.au/documents/lrtprocon.html

As with many early U.S. systems, MTOC operated tramsets consisting of an open-sided "grip," from which the driver moved the vehicles by gripping and releasing the moving underground cables.
https://riid.tripod.com/cable.html

In Vienna and similar cities, trams much more frequently operate along their own rights-of-way and often run in tramsets of two, three or more cars.
https://medium.com/@PeterTSmith/placing-a-baltimore-streetca...





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Note added at 8 hrs (2023-03-22 10:36:39 GMT)
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As Polyglot points out, it's probably by analogy with 'trainset'.

The difficulty is that while a train is necessarily a 'set' (otherwise it's a locomotive), trams run both as single cars and multiple cars hitched together.

Do not confuse with 'train set' (or 'tram set'), as Wikipedia points out:

"Train set
A toy train with its tracks, buildings, etc.[256]
Trainset
A group of rolling stock that is permanently or semi-permanently coupled together to form a unified set of equipment. Trainsets are most often used in passenger train configurations.

There might well be another term. It's not easy to find 'tramset' in isolation from 'Alstom'. According the French Ministry of Foreign Affairs, Alstom is (or was) the second-largest manufacturer of trams with 20% of the world market (this may have been before they took over Bombardier). What do other manufacturers say, I wonder. I suspect they simply say 'tram', leaving the reader to understand whether it is a 'single-car tram' or a 'multi-car tram'.



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Note added at 8 hrs (2023-03-22 10:37:42 GMT)
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Bother, missed a < /b>.

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Note added at 13 hrs (2023-03-22 16:17:14 GMT)
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Actually, now that I see this is about Alberta, this might need specific localisation. I'm not actually aware of any trams in Alberta, but Calgary and Edmonton have LRT (light-rail transit) systems which, in French parlance, are probably called tramways. When they are up I'll try to check with cousins Darlene and Dixie in Calgary and Edmonton ;-), but I suspect locals will call simply call their rame the CTrain or LRT train. It is true though that Calgary's CTrain is a light metro train that "in the downtown free-fare zone trains transitions into a tram with a dedicated right-of-way".