6. The Queens Midtown Tunnel Had 23 Ventilation Fans, Each the Size of a Car

Street sign that says "toll billed by mail"

Thanks to the Wired New York forum, we learned that the tunnel originally had 23 ventilation fans, each the size of a small car. They were “exhausted,” however, after 65 years on the job. As part of a $18.8 million dollar renovation, the carbon-steel bladed fans were replaced with stainless-steel ones, which are easier to maintain.
The fans (seen here), which clear the tunnel of pollutants and carbon monoxide, move 2.8 million cubic feet of air per minute, and can completely clear out both tubes every 90 seconds. Another feature that has changed since the tunnel’s opening is its original brick roadway, which was replaced with asphalt in 1995.