An extra tunnel would alleviate the pressure on the tunnel, so why not just revive the ARC tunnel, which was so far along already? One reason is the MTA's new 7 line extension to Manhattan's far West Side. "Those changes in Hudson Yards precluded the ARC option," Richard Barone, vice president of Transportation at the Regional Plan Association, said. "So it's actually in the way."
Listen to the full segment on WNYC.