The problem is that digging a tunnel is expensive even when amortized over the 30,000 passengers per hour that a subway line can carry. When you amortize it ove

The problem is that digging a tunnel is expensive even when amortized over the 30,000 passengers per hour that a subway line can carry. When you amortize it over the 2,000 passengers per hour that a lane of single-occupancy vehicles maxes out at, the expense is completely outrageous.