A couple of years ago, I was with my friend Adam Cohn when he made this simple yet important declaration — “San Francisco should always have a subway under construction.” My first reaction was to think of every possible objection to the concept — too expensive, too disruptive, too controversial, too many difficulties siting subway stations and determining alignments.

A couple of years ago, I was with my friend Adam Cohn when he made this simple yet important declaration — “San Francisco should always have a subway under construction.” My first reaction was to think of every possible objection to the concept — too expensive, too disruptive, too controversial, too many difficulties siting subway stations and determining alignments.