Given the proximity and position of the viadict, this trolley is approximately where the Darigold Dairy is today. I think that staircase on viaduct is the one up near Caruthers street, although a lot of them have been demolished.
Where is Bell Rose, you ask? A stop on the way to Gresham, as this map indicates.
I don't know if you had to transfer lines to keep going or if Bell Rose was just short hand for "this trolley goes to Gresham and not Oregon City."