IIRC, the original PR for this gave the idea that automobiles would enter the tunnel through single-car elevators that looked like parking spaces. How many suc

IIRC, the original PR for this gave the idea that automobiles would enter the tunnel through single-car elevators that looked like parking spaces. How many such elevators are needed to keep a high-cost roadway running reasonably full? How much infrastructure (safety barriers, driveways, waiting areas, not to mention people) around each elevator to move the cars on and off safely?