The costs of building urban train transit per mile vary amazingly. An article here from the Atlantic says: NYC plans 8.5 miles estimate at $17 billion, or $1,240,000/Km. Madrid just built 41km for $58,000 per Km. Singapore just built 22 Miles with 28 stations for $4.8 billion - $139,000/Km. Paris and Berlin estimated recent additions at $250,000 per Km. We cost ourselves 5x-20x what others do this work for.
Accurate Reality: We could do more with our government money if it didn't cost us so much to do it.