One of the pernicious myths about traffic is that we can redirect or channelize traffic in order to save other places from traffic.
We see this in our street heirarchy, in which we channelize traffic to collectors and arterials in order to shelter local streets.
We see this in parkways, bypasses, and beltlines, all aimed at channelizing traffic for efficient flow and to remove it from other places.
Back in 1972 there was here an early version of this. The "Central Salem Development Program" envisioned multiple plazas downtown on Liberty Street at the intersections with cross streets. While Liberty was not envisioned as fully pedestrianized and closed to car traffic, it was understood as a slow street and appears to have chicanes on it even.
To provide the shelter for those plazas, it relied on a traffic plan focused on the Front Street bypass and Pringle Parkway. It also would have routed more traffic on the High/Church couplet, and blasted through a continuation of 12th Street north of Safeway.
The CSDP traffic plan would remove through traffic from Commercial and Liberty Streets and thus allow more convenient parking, more landscaping and better pedestrian environment in the retail core. A system of "bikeways" is proposed along the Willamette riverfront, the creeks and some streets.
It also proposed even larger parking garages than we actually built. One
of them would have taken out the Grand Theater, for example, and the
Chemeketa parkade would go one block further north, taking out the Wilson garage (Santiam Bicycle) and also use the Rite-Aid parking lot.
Though we did not expand the High/Church couplet or blast 12th street, the Front Street bypass and Pringle Parkway have not removed sufficient traffic from Liberty Street to make those plazas.