This is now on my Medium
The intersection of Commercial Drive and Broadway is today a major interchange station between SkyTrain's Millennium and Expo lines, and the rapid bus 99 B-Line. Historically, this area has been of major importance the two BC Electric Railway's interurban lines which served east Vancouver (the Central Park and Burnaby Lake lines) merged with the street car serving Commercial Drive to then feed into downtown.
However, this produced a major choke point as having three different rail services interlining on a single street created serious congestion challenges for the BCER. A solution proposed in the 1920s was a proposal to extend the Central Park line from Victoria and Hull all the way to Main Street.
This would have extended the line northwest along the curve where Victoria turns into Commercial, then crossing Clark and Broadway, with a tunnel under St. Catherine's Street, then following along E. 2nd Avenue until finally turning to cross False Creek, then finally terminating at the Great Northern Station located at Carrall and Keefer.
Overlaying the map from the 1930s on something modern takes a lot of guesswork as you can tell, but this gives you a pretty good idea of what the Expo Line could have been.
With the onset of the Second World War and decade-later closure of the Central Park line, these plans were never meant to be. The modern Expo Line now turns away from what was then Cedar Cottage (now a community garden) and crosses over Broadway and Commercial to follow the Grandview cut towards downtown.
That said, with the extension of the Millennium Line to Arbutus, a tunnel is now going to grace the neighbourhood of Mount Pleasant after all.
