Some people seem to be taking it a bit far. I mean, I'm not sure why it would be such a hard blow for Calgary to not have a "rapid transit" system. For a city of it's size it's very impressive to even have a full, high ridership LRT system, considering much larger places including Dallas, Seattle, Houston, Denver and Phoenix only have LRT systems, some of which were only built in the last few years. There are only a couple of (much older/denser) metro areas in Europe that have rapid transit systems with a population as small as metro Calgary. Many places like Porto for instance have what they refer to as a "pre-metro" which is basically what we call LRT in NA.
But ok, there is a definition on APTA's glossary PDF for an industry source.
"Rail or motorbus transit service operating completely separate from all modes of transportation on an exclusive right of way"
http://www.apta.com/resources/reportsandpublications/Documents/Transit_Glossary_1994.pdf
And from Encyclopedia Britannica:
"system of railways, usually electric, that is used for local
transit in a metropolitan area. A rapid transit line may run underground (subway), above street level (elevated transit line), or at street level.
Rapid transit is distinguished from other forms of mass transit by its operation on exclusive right-of-way, with no access for other vehicles or for pedestrians. See elevated transit line; mass transit; subway."
http://www.britannica.com/EBchecked/topic/491506/rapid-transit
But anyway, as interesting as cross over SUVs may be, I see no connection to the topic, as C-train definitely isn't a crossover. It's a full LRT system. In fact, it's one of the earliest examples of a true, North American LRT system. However, Vancouver Skytrain can be cited cited as a crossover between LRT and metro (sometimes dubbed "light metro") since it has all of the characteristics of a full metro system, but uses unusually small trains which is more similar to light rail.
SF's BART and Paris' RER on the other hand, are both crosses between rapid transit and commuter rail with BART being true rapid transit using full grade separation but lower branch frequencies, while RER has over 70km of metro-like tunnel operation, but has some level crossings, and often uses bi-level cars.