The recently-completed St. Clair LRT, like other Toronto LRTs, is very different from Waterloo Region's proposed LRT: in Toronto an LRT is a streetcar that stops every two blocks, while in Waterloo the proposed LRT is a train that stops every 1.5 kilometers. But the tracks will be similar. Here's a picture I took on St. Clair today:
The LRT tracks run on a wide, raised platform in the middle of the street. Cars can't cross it, so if they want to access a parking spot, driveway, or even small street on the other side of the LRT tracks, they have to go to the next intersection and make a U-turn. The U-turns require special U-turn lights, and that means that the green lights for going straight are briefer than they would otherwise be. Today on St. Clair it was Sunday and traffic was very light, but it was painfully slow because I got stopped by a red light at every intersection.
In Waterloo region, the long distance between LRT stops means that we'll need buses to run the same route. That will compound the problem - and the current thinking is that we shouldn't have bus bays.
As this snippet of the region's map shows, the LRT prevents left turns at certain intersections, such as John and King. Cars wanting to make a left turn there will have to proceed to the next intersection and make a U-turn.