First of all, and this has already been mentioned before I believe, but this extension has a lot of challenges. A tunnel under 23 Ave, the bridge over Blackmud Creek, the bridge over the Henday, and while it's not a challenge exactly, the OMF is needed and won't be cheap. However, once the SLRT reaches Ellerslie Road, the extensions after that should be relatively straight forward and cheaper. This isn't unlike 25 or so years ago when the push was to just get the LRT out from under the University as after that was done it, would be much easier to get the extension to Century Park. Now, that argument certainly also exists for getting the Metro Line over Yellowhead and Walker yards... but that's another thread.
I'm not sure how many people realize the amount of bus traffic from Century Park uses 111 St. I remember in the early days of the BNR being awestruck at the amount of buses at Century Park during AM and PM peaks and the frequencies on the 721 and 722. I think they have scaled back some of the routes to better align with post Covid ridership, but, there is still a substantial number of buses.
How many? I did some counting based upon the PDF schedules.
I was just counting SB departures from Century Park and NB arrivals at CP. AM I used 7:00-9:00 and PM I used 15:00-17:00. I only included routes that travelled south of the Henday (so no 713). Those routes are: 521, 700x, 718, 719, 721, 722. This doesn't include any school extras.
NB AM= 94 buses
SB AM= 43 buses
NB PM= 42 buses
SB PM= 75 buses
AM total= 137 buses
PM total= 117 buses
Since the PM peak is usually spread out longer, you'll probably end up with close to the same total overall number of buses between the two peaks. These numbers are just a snap shot for a 2 hour period.
The stretch of 111 St between Century Park and Ellerslie Road is 3.3 KM, so, while you're not fully eliminating these buses with this LRT extension, for that stretch of road you're getting a significant number of buses off of the road, and not to mention, the concentration of diesel exhaust from them.