>>1521250The problem is the density in many north american cities isn't centralized. There are sprawling suburbs of every major city, and commuter rail that brings the suburbanites into the urban core. Downtown Toronto uses streetcars (trams), many in mixed traffic, or partly mixed partly right of way etc.
One street they recently closed to through traffic so the streetcar essentially has full right of way.
Tunneling part of the LRTs just burries them in the busiest section of the city while allowing easy expansion into suburbs on the surface
