I have never been to Manhattan, and I am confused about one thing: How does the Grand Central Terminal tunnel work? I've seen photos of this building, but all around it there seem to be old steel overpasses. What are these for?

• ID# 48.2 (reply to #48.1) - 17 Jul 1998
  Grand Central's two-level underground railway yard and tunnel were originally an ordinary open-air terminal station, until, in 1913, the completion of electrifying of the railway network and the new terminal led also to covering of the rail yards, and renting out the air rights above the tracks for development. The enormous weight of the surface and buildings above is supported on steel platforms. The railway tracks from the station run in a tunnel underneath Park Avenue until they surface at 96th Street to beautify El Barrio...
  As the Terminal (together with the Helmsley Building and Met Life Building) blocks Park Avenue, the traffic has to be directed through and around these buildings between 42nd and 46th Streets. Two steel bridges carry the traffic over 45th Street, and 41st and 42nd Streets are spanned by the Pershing Viaduct in front of the station. ED

• ID# 48.3 (reply to #48.1)
  From: Frank Gerlak (fgerlak@apk.net) - 2 Mar 1999

  Check out the Life Magazine of November 7, 1949. On page 85 is a cut-away of Grand Central Station down to one of my favorite "haunts" there, the Oyster Bar.

• ID# 48.4 (reply to #48.1)
  From: John J. Ragusa (jrjr1059@yahoo.com) - 4 Mar 1999

  I also suggest purchasing the video on Grand Central Terminal from A&E's History Channel which was shown all day long in the Vanderbilt Room of the terminal a few months ago as the rehabilitation of the building was nearing completion.

• ID# 48.5 (reply to #48.1) - 27 November 2001
  Also, this from The New York Times:
  "The original New York and Harlem Railroad first ended at 90th Street in 1834, until a tunnel was cut in the East 90's under what is now called Carnegie Hill three years later. Most of the rest of the track, from 42nd to 90th Street, ran in an open cut, with occasional bridges to allow cross-street traffic. The first Grand Central Terminal was finished in 1871, increasing traffic so much that area property owners persuaded the railroad to cover the tracks.
  "In a large-scale project north of 56th Street between 1873 and 1875, the engineer Isaac C. Buckhout designed beam tunnels — in which iron beams span the tracks directly above the rail traffic — for areas where the land was low. Where the land was high enough, conventional masonry arch tunnels were built.
  "The tracks south of 56th Street were covered over as part of the construction of the new Grand Central Terminal, completed in 1913." NYT, 25 Nov. 2001
  ED