The 7 Line seems like a nearly perfect route for Dovetail to do, its about a 30-45 minute drive end to end. About 1/4 of the line is underground, from 34st - Hudson Yards to Queensboro Plaza, and the rest is elevated until Flushing. Trains run very frequently which I think we can all agree is important, and since they've done a London Underground line a New York City Subway line seems logical for us across the pond.
Queensboro Plaza isn't an underground station, 34th St-Hudson Yards to Hunterspoint Av is underground. then it's elevated from Court House SQ to Willets point, then the last stop (Main St-Flushing) is underground.
