Architecture firm SOM has proposed adding a floating observation deck that slides up and down the sides of two new skyscrapers .The moving deck is one of several public realm strategies that the firm is promoting for the 100-year-old station, following an invitation from the Municipal Art Society of New York to re-think the spaces in and around the building.SOM suggests that the hovering deck would improve the quality of the public space around the building by offering an "iconic landmark" with a 360-degree panorama of the city skyline."Throughout the history of New York City, urban growth has been matched by grand civic gestures," said SOM partner Roger Duffy.