New York City’s subway lines – the engines that keep the city’s real estate market moving – are notoriously expensive to build. Tunneling projects in New York routinely clock in at five to ten times the cost of their Asian and European counterparts, putting the city’s measly 20-30% aboveground union construction premiums to shame. New York has finally restarted work on the century-in-the-making Second Avenue Subway, but MTA capital construction president Michael Horodniceanu says that anything beyond the initial Upper East Side segment “will be for our children or grandchildren.” And Bloomberg’s 7 train to Secaucus, or those fabled Utica and Nostrand extensions?…