Regardless of coupler type, the big question is heavy rail or light rail vehicles? (such as Sprinter DMUs) If it is light rail, then the freight operations have to operate with the track to themselves at off hours (night).

Then you run into low floor or high platforms. An interpertation of ADA rules (still apparently being argued) claims the entire train must be handicap accesable from from the same level of any opened door, and not less than a 3" gap. This is what is requiring gauntlet track or moveable platforms to clear freight trains.

I bet if you changed requirements to REASONABLE handicap access instead of unrestricted, and then dropped many of the sound walls and the numerous public enhancements, it could be built for far, far less.

There is no comparison to what our tax money pays for that consultants have designed compared to the for-profit operations built a century ago. But then again, most people welcomed any additional public transit options.