Expanding the train station, the busiest in the nation, is a pressing issue because construction has just begun on a $16 billion pair of rail tunnels under the Hudson River, the centerpieces of a project known as Gateway, which would double the current cross-Hudson capacity.

With no movement on plans to redesign and renovate Penn Station, a public interest group is suggesting moving Madison Square Garden across the street and replacing it with a much bigger train station and park.

Under the plan by the Grand Penn Community Alliance plan, Penn Station will move above ground while Madison Square Garden is relocated.