Here's a website showing the walkability of each O-Train Station. It includes a generally more realistic view of that 15-minute walking distance (with a few odd ones like Algonquin, which is very much under-counted).  We can see the relatively significant density along the Bayshore-Lees and Bayview-Carleton, while the rest serves few people within that 15 minute walk (with a few exceptions). 

https://onedu.maps.arcgis.com/apps/MapSeries/index.html?appid=faae1c57849a40e6859d5ddce5e3eda0

Very interesting find. Really illustrates clearly the populations in proximity to each of the stations. It does appear less ideal than it sounds at first glance. 5km as we have often discussed is not a reasonable walk-able distance and not something most people can be expected or even want to do. It would be very interesting to see it shown more as 1km from the stations. Surely those near Rideau, Bayshore, and other high saturation areas would peak on such a list with the rest being quite low. Even locations like Jeanne d'Arc or Convent Glen with housing on both sides of the highway would show as low as they are single dwelling homes so the population per square km is low by comparison to highrise apartment and condo neighborhoods.

Thats probably one of the biggest costs from building the east extension in the middle of the highway, makes the walkability quite low through the entire alignment.

I personally don't think using any distance based measurement really tells the whole story versus a 5 / 10 / 15 min walk: elevation, proper sidewalks, etc. This map really gives a good idea of how far I would actually myself be willing to walk to a station, within a few exceptions where the time estimate is really on the slow side.

I think it also helps explain why the city does not use this measure versus their 5km distance as it would probably be harder to "sell" people on the O-Train this way...

It does seem like the map only considers sidewalks and not off road pedestrian paths or pedestrian bridges, which explains Algonquin and a few others having so little access.

The argument for using the highway median instead of building on one side or the other would be to have the station equa-distance between the north and south. There's also a financial advantage by not having to under the road embankments on each side (as they rise over the highway) as will be the case with Pinecrest, for example. But yeah, unpleasant experience for sure.