[rypinion]

The 15 Mountain bus gets you downtown from the airport really quick. I don't know why more people don't use it. I use it to get to and from the airport, and it is super convenient, whether I am coming from home on North Main street by Chief Peguis, or coming from work at Portage and Main.

As kyle_olsen alludes to, the BRT in Ottawa is on dedicated roadways. If it wasn't, I don't think it'd be called BRT, it'd just be "the bus". I don't see a speed difference between a bus on a dedicated roadway, or a skytrain, except that the bus has the flexibility to go onto the regular road network when need be. (There are other advantages to a skytrain like system though, but I don't necessarily see speed as one of them)

Added: If you look at maps.google.ca and look at the map of Ottawa, you'll see little grey roads all over the place called "transitway". They appear to bypass most major intersections.