Transit Authority

Q: Roughly halfway through the Holland Tunnel, there is an exit sign and a door next to it. Where does the door go?

A: Turns out the door leads to exactly what the sign says: an exit. The Holland Tunnel comprises two 1.6-mile-long tubes, each with two exits: one leading to New York, another to New Jersey. The exits serve two functions. They provide a means of pedestrian escape in an emergency. And maintenance crews may use them to get into the tunnel without their "Cat vehicles," which would block a lane of traffic.

The Lincoln Tunnel has three tubes and eight exits. Its first tube opened in 1937. Not only are there more exits, but there is a crossover that connects the Lincoln Tunnel's tubes. The Brooklyn Battery and Queens Midtown tunnels have similar exits.

"For security reasons," neither Mr. Pascual nor a spokeswoman from the Port Authority would tell me where exactly the exits lead, but assured me they go "to safe places."

The control centers are manned 24 hours a day, seven days a week. Unauthorized users would likely be arrested and possibly suspected of terrorist activity. So, late-night thrill-seekers, consider yourselves warned.

Got a question about getting around New York? E-mail transit@nysun.com.