I finally figured out why the Beatty/Dunsmuir intersection is so undersized for the amount of traffic it carries. It used to be
way bigger. Looking at some pics of Expo I came across this gem showing the configuration in 1986. This makes a lot more sense, although I have no idea when some of these things were changed.
Source: CanadaGood on Flickr
Linky
Beatty used to be 1 way, allowing for only one turn direction to occur. Just before the intersection, Dunsmuir was 6 lanes across. Configured as through/through/through/through/right/right. Compared to today's 3 lane cross section of left/through/right, where the left lane is mostly clogged by turning traffic.
Does anyone know why the one way system was scrapped on Beatty and Cambie? Also, what precipitated the sidewalk changes? GM place construction?