outside the box thinking is imperative. to achieve a solution that is affordable(relative to others), in a relevant time frame is the goal
I spent my career(33 years) in transportation. the only solution that I know of is something so radical and so bizarre that most just dismiss it. But it could work. "The Wire" is a solution that has been floated before but got no traction. Think automated, routing and demand optimized air-conditioned, wifi equipped gondolas moving along aerial rights of way at a decent clip of 20-30 mph. surface(at grade) or subsurface(subway) systems fail due to numerous reasons mainly time, density or funding based type fatal flaws. a working gondola based system is the best approach to address the generalized fatal flaws. going aerial maximizing existing rights of way with pole and cable based infrastructure could be the ticket. It will take courage and vision. I have no interest in anything or anyone associated with "The Wire" only a desire to see my home city I've lived in since birth reclaim it's liveability because it's losing it right now due to mobility issues.