The Pennsylvania Railroad, the largest and wealthiest in the US in 1900, tended to build big. After decades of serving New York from the south with service ending in Jersey City and ferries across the Hudson River, a plan was developed to provide a direct link. The Pennsy bought the Long Island Railroad, built tunnels under both the Hudson and East Rivers, built a station in Manhattan, and built a yard in Queens to service that station. The LIRR, East River, and Queens portions of the project were necessary for efficient operations: they made Pennsylvania Station a through station rather than a dead end.
The picture above shows the station nearly complete, probably in summer or fall of 1910. You can see a few men on the roof, and cranes working on stone off in the distance down 33rd Street. The construction fence is still up, although portions have been removed. The most interesting thing in the picture is the big hole in the ground in the left foreground, across Seventh Avenue from the station. This lot would be, nine years later, the site of the Hotel Pennsylvania*, a 2200-room behemoth. It did not take nine years to build the hotel, so what’s going on here?
There are four single-track tunnels under the East River which follow the lines of 32nd and 33rd Streets west to the station. Those four tracks have to spread out to cover the multiple platforms and tracks in the station** and so there is a complex of switches and diagonals east of the station. That hole in the ground most likely represents backfill after the tracks in this areas were constructed.
* The hotel is best known for its front-desk phone number, 736-5000, which in the days of named exchanges was PEnnsylvania 6-5000.
** Coverage is not perfect: tracks 1, 2, 3, and 4 are too far south to be served by the East River tunnel approach, and so are only used for local transit to New Jersey.
