If you slogged through the New York Times story on NJ to NY tunnel milestones, maybe this made you pause, too.
"No one knew if that tunnel was 100 percent safe until trains had been going through it for many years," Jill Jonnes, the author of "Conquering Gotham" (Viking Adult), which details the building of the tunnels and Pennsylvania Station, said in an interview. "They really didn't know how long the tunnels would keep sinking in the mud and whether they would crack. There was no precedent for a tunnel having hundreds of 700-ton trains going though them."To this day, the tunnels continue to drift ever so slightly in the riverbed.
Now that's a sobering thought.