Underpinning Historic Structures at Grand Central Station, New York

The historic Hotel Commodore was designed by the famous structural engineer Homer G Balcom who also designed the Empire State Building. Built in 1917, it is located directly above and supported by the Grand Central Station railroad and subway structure below. In 1979 the hotel underwent major refurbishment before being reopened as the current Grand Hyatt. This paper will describe recent research and design work undertaken to accommodate major structural changes required to open up space and increase headroom at the subway mezzanine level to improve passenger flows. This involves underpinning and load transfer of the hotel structure above using temporary support, sequencing and jacking. The history of hotel and its famous designer will be documented together with commentary on the structural design and construction methods employed at the time.