Sorbus x thuringiaca 'Fastigiata' is seen elsewhere in the region and looks generally like this. If it is not this same exact one it will put you in the ball park.
Thanks, my friend said two line of mature trees alternate with plum are located SW of Mons Dr. & Worthington Dr., Vancouver at https://goo.gl/maps/xKa5x
On the city's list as Sorbus aria or S. aria 'Lutescens', which they're clearly not. The soon-to-be released Vancouver Trees app does have Sorbus x thuringiaca as a tree occasionally seen around here.
Quite similar to Swedish Whitebeam S. intermedia but not quite right (leaves too narrow, crown wrong shape). Not sure it is S. x thuringiaca though, as that usually has the basal one or two lobes as separate leaflets.