Gateway is the most urgent infrastructure project in the United States. The additional rail tunnels that it would create under the Hudson River would allow the two aging tunnels we have today to undergo needed repairs while accommodating growing demand in a corridor that supports 20% of the national economy. The project would also be one of the nation’s most expensive, with the tunnels alone estimated to cost $11.1 billion.

Gateway has attracted its share critiques and recommendations for how to make the project better or less costly. While investments of this scale should always be examined for potential improvements or savings, some prominent ideas are based on erroneous assumptions. In this three part series, we’ll uncover why these myths need to be discarded to prevent the project from being unnecessarily delayed.

Myth #1: It would be better to build one tunnel now at half the cost to start repairing the existing tunnels.

Reality: A single tunnel would be unsafe and limit future capacity by more than half.

Modern safety codes require that tunnels have an emergency exit every 2,500 feet or cross-passageways every 800 feet. If only one tube was constructed the tunnel would require a separate evacuation tube, which would still require two bored tunnels, and though the second would be smaller, it would not result in significant cost savings over the two-tube approach.[1]

Engineers worldwide have addressed this issue by using two tubes with cross-passageways, or small connecting tunnels with fire doors, allowing for the riders from one tunnel to evacuate to the adjacent one in case of emergencies. This design and evacuation procedure has been proven in facilities around the globe such as the English Channel Tunnel or Chunnel and right here at home on the recently opened Second Avenue Subway. The new Hudson River tunnels will have 15 cross-passageways that will be spaced at intervals of 750 feet[2]. Two tubes will ensure that in case of emergencies customers will be able to cross into the other tube and board an evacuation train.

A single tube approach would also severely limit the capacity of Gateway once the expansion of the Penn Station is completed. The new tunnels would enter Penn Station south of the existing interlocking, limiting their access to the station’s northern tracks. Without the additional tube the capacity of the station will be decreased by at least half of what’s currently planned because when rail terminal is operating at its capacity, the trains that come in to the terminal via a rail tunnel must either go out in another rail tunnel or accumulate in a yard within the terminal. There either needs to be an even number of tunnels, or a big storage yard built to hold the excess trains. Otherwise, a single new tunnel (creating an odd number) would only have capacity equal to the absorption capacity of the existing station tracks and yard space – which would likely be 10 trains or less over an entire peak period. This will substantially reduce the number of trains that the station can accommodate and result in less reliable service and more crowding. It will likely eliminate most if not all of the planned one-seat ride service improvements for customers on the Bergen-Main, Pascack Valley and Raritan Valley Lines.

Footnotes

1. Why not connect the new single tunnel to the old ones? The reason here is straightforward, the new tunnel alignment is not adjacent to the old ones for many reasons, and safety is one. The North River tunnels are over 100 years old and there are serious concerns about disturbing the earth around them. Any actions that would require breaching the structure of these old tubes is considered to be too risky since it could result in their failure.

2. Hudson Tunnel Project: Project Alternatives and Description of Preferred Alternative