Picture this: a Triboro train line

The crux of this report is pretty amazing.
TL;DR: Thanks to an existing rail right-of-way in New York City, a 24-mile line could run from Bay Ridge, up through Queens and around to Co-Op City in the Bronx, without ever touching Manhattan.
See the gist of the report’s broader findings here. It’s from the Regional Plan Association, so the full report goes on forever, but you can get the whole thing here. We first spotted it in this post from Home Reporter. (Current New York City Comptroller Scott Stringer had been championing the idea of a so-called “X Line” as recently as 2012.)
As for the cost of the project, the RPA told Capital New York it couldn’t provide an estimate.
Interestingly, a line like this would probably be a real boon for Manhattanites, as it would take pressure off the overcrowded Manhattan lines. The current rail system forces many riders to pass through Manhattan to get elsewhere. According to the RPA report, the city’s rail system sees almost three times as much ridership as the bus system.
This report complements Mayor Bill de Blasio’s idea of expanding the ferry system to move more New Yorkers over water, as well. In his most recent State of the City address, de Blasio argued that transit access is a jobs issue.