The LRT passes through the intersection as it heads south on Caroline Street on its way back to Kitchener.
The Region is planning to have the LRT tracks go kitty-corner through the intersection. Here is a snippet of the Region's map, showing what this intersection will look like when the LRT is built (you can see the complete map here):
Caroline is the street running horizontally across the map. Notice how the thick pink line (the LRT) starts out on one side of Caroline but crosses over to the other side in the middle of the intersection.
What this means is that whenever the LRT goes by (which will be every 7 minutes, on average), all traffic in all directions will have to come to a halt. Had the LRT tracks stayed on the same side of the street through the intersection, the disruption would be much more minor: the LRT could have flowed through the lights with the rest of the traffic heading in its direction.
Since most traffic in this intersection is using the short jog on William to get from Park to Caroline (or vice versa), this means that at rush hour, the traffic waiting for the light to change will be backed up along Park and around both corners.
The problems at this intersection are minor compared to some other problem areas in the LRT plans for uptown Waterloo: the LRT is also going to make a mess of the King-Erb intersection and the Erb-Caroline intersection, as well as make it difficult for cars on Erb to turn on to Albert. These four huge problems are all in the very small area of our uptown core.
Here are some previous posts I've written about the LRT plans for uptown Waterloo:
Rapid Transit Part 1: Rapid Transit is Poised to Destroy Uptown Waterloo
Rapid Transit Part 2: First, Do No Harm
Rapid Transit Part 4: How Uptown Waterloo Could Fail
(By the way, I no longer refer to the LRT as "rapid transit" since I learned that the LRT will be only about 7 minutes faster than the iXpress is getting from Conestoga Mall to Fairview Mall, the end points of both transit lines.)