Nitpick: it is one life per year for the billion invested. Which after the typical metro infrastructure lifespan of a century is actually viable because the cost for a working-age US life in medical and other contexts is probably around the $10mn ballpark.
(Assuming financing happens cheaply by the federal state rather than via PPP grift; and assuming that $50bn is the number, which in NYC is an underestimate by a factor of at least five…)
That’s a really good point. This is all very back-of-the-envelope, but if the total cost per life saved were 10 million it gets into the ballpark of sane.
But as you noted this 50 billion is likely a major underestimate (for comparison the recently built SR-99 tunnel in Seattle cost 1 billion per linear mile and connects to approximately zero buildings via elevators). NYC covers 300 square miles and estimates are that there are upwards of a million buildings across 120k city blocks.
(Assuming financing happens cheaply by the federal state rather than via PPP grift; and assuming that $50bn is the number, which in NYC is an underestimate by a factor of at least five…)