Last week’s revelations of a scheme to blow holes in the PATH tunnels wasn’t the first time engineers had to worry about river water pouring into the tubes.
Concerned about just such a disaster shortly after the 9/11 attacks, the Port Authority installed two massive concrete plugs, each 16 feet in diameter and 17 feet thick, to close off the tunnels at Exchange Place in Jersey City.
The devices prevented floodwaters from pouring out the Jersey side and through connecting tunnels that lead back across the Hudson into Manhattan at 34th Street – a catastrophe that could have knocked out subways from Greenwich Village to Central Park.
Engineers installed the plugs after 9/11, when water levels at the Exchange Place station, 20 feet lower than the World Trade Center station, rose to more than half a foot.
The water, believed to have come from rain, broken pipes and firefighting equipment at Ground Zero, was negligible compared with what would pour through the tubes if the walls keeping river water out of the World Trade Center site gave way.
The plugs were eventually removed, and the tunnels were drained and extensively repaired before trains resumed operation between Jersey City and the World Trade Center station in 2003.