Why can't a trial be done where the viaducts speed is greatly reduced down to the average speed on surface streets, 20-30kph, and analyse traffic flow patterns?
I'm personally for keeping the viaducts, and my guess would be that alot of viaduct traffic would convert to using surface streets. Hopefully will show the mayor and council that if they want to keep the surface streets bike, pedestrian, and streetcar freindly, that they would want to keep the Viaducts.
Or of course if more traffic on local streets is the result, they could develop the perverse opinion that removing the viaducts simply isn't enough to cut traffic. From there I could see them closing or limiting surface streets to traffic aswell.
Of course, I also think a series of tunnels could be constructed under downtown so that traffic going to/from the Lions Gate Bridge from the South and East don't have to drive through downtown to get to the bridge. One tunnel could approach from the south following the basic route of Granville. The southern terminus being near the bridge on the south side of False Creek, or a pair of ramps from Granville once on the penninsula, and it could intersect or merge with a tunnel travelling west to east from Stanely Park to the eastern edge of the ducts.
This would lead to two scenarios:
A. Keep the ducts, and build the tunnel underneath.
B. Remove the ducts, and have the tunnels eastern terminus at Main st.
Of course I could also see the argument being put fourth that if you are going to construct 3-4km worth of vehicle tunnels downtown, why don't you just put a tunnel all the way underneath the inlet to North Van?