A Tale of Two Tunnels

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Anyone who ever lived in New York City can tell you the Holland Tunnel, stretching more than one and a half miles, is more than a traffic ease—it's vital. But, says architectural historian John Gomez, making sure the air in and around the tunnel would be clean was no easy task for engineers.

The Old

"They were using actual people in tunnel scenarios to see how much carbon monoxide they could stand before they would die," he says. "They used abandoned coalmines for their testing and set up makeshift vehicular tunnels to carry it out. There are pictures of people passed out in these cars. It was intense."

Gomez describes the ventilation towers we see today as skyscrapers in a river. "They had to spread out the ventilation and, within the water itself, to spread out the system," he says. "They would have put towers right in middle of the river but couldn't because of shipping and tugboats."

Old photo of the inside of a Holland Tunnel ventilation tower. Image: Eric and Edith Matson photograph collection

And while the leader of the project, Clifford Holland, bears the name of the tunnel, the "Ole Singstad" ventilation solution was critical. Explained by the website of the Port Authority of New York and New Jersey: "Singstad's solution was to design a circular tunnel with an automatic ventilation system. Four ventilation buildings, two on each side of the Hudson River, house 84 immense fans that provide a change of air every 90 seconds, keeping air quality well within established safety limits."

Gomez says the transfer airflow from toxic air became a milestone. "They were so confident it would be successful that they already had it in mind for the Lincoln Tunnel while still working on the Holland Tunnel," he says. "Many major tunnels made the change to this after its success."

The New

The "Chunnel," a much more modern construction, had ventilation issues to consider as well, especially with the effect on air that high-speed trains possess. According to the book Proceedings of the Institution of Civil Engineers: The Channel Tunnel, the paper "Tunnel Ventilation, Including Aerodynamics" by A.G. Fairbairn explains ventilation was also dominated by the lack of access for service connections. Fairbairn said that there were "bulkhead type doors at the running tunnel end of each cross-passage, thus isolating service and running tunnels. This allowed the service tunnel to be used." In addition, the paper says the train speed air effect was worked on with spaced ducts to both connect the high pressure of air before the train and the low pressure at the rear of it from the other running tunnel.

The Chunnel had ventilation issues to consider as well, especially with the effect on air that high-speed trains can have.

The paper also points out that a supplementary ventilation system was created in case of train malfunction or possible fire. Aspects such as pressure relief ducts, according to Fairbairn, can close in one tunnel to isolate where the issue is and allow the other tunnel to bring help.

But, of course, ventilation is not what most people think of when they consider the grandeur of these tunnels. That, Gomez says, is part of the point.

"When you don't hear about ventilation issues and instead take in the sight of it, that's when the people who created it have done their job," Gomez says.

Eric Butterman is an independent writer.

When you don't hear about ventilation issues and instead take in the sight of it, that's when the people who created it have done their job. John Gomez, architectural historian

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