On April 13, 1992 the Chicago subway flooded months after an abandoned freight tunnel under the Chicago River was breached. It took 18 days before the subway was opened for business.
There are some major differences with the Chicago flood and the New York flood.
The Chicago flood was fresh water, while in the New York flood, rain water is mixed with seawater, so the much older electrical equipment in the NY subways may require even more extensive repairs of items that are no longer manufactured.
The Chicago subway was completely filled, but the Chicago downtown subway system is smaller than the New York subway system. While the extent of the flooding in NY subways is unknown, it is probably much larger in scope than the Chicago flood.
Since both a subway and an elevated train serve downtown Chicago the subway traffic could be re-routed at junctions above ground to avoid some of the subway tunnels. Downtown New York City does not have this option.
Check out OllieGarkey's diary The Subway may be down for a while for info about the New York MTA subway system flood.
Another diary by New Minas MTA--"Weeks" with more info about the damage to the New York subway system.
Drop below the orange waves to read more about the Great Chicago Flood of 1992.
The tunnel system under Chicago has been used for many purposes, freight with 24 gauge electric trains, telecom and power lines, even selling cool air to theaters before the advent of air conditioning. The freight system eventually was abandoned by 1959, but the tunnels are still used by the utilities. When the water with fish swimming in it started rising in the basement of the Merchandise Mart, it turned out that the water was coming from a whirlpool in the Chicago River through these now little used tunnels.
For a technical review of the event, this article in STRUCTURE magazine written 15 years later is very detailed with pictures and diagrams.
STRUCTURE Magazine - The Great Chicago Flood
The source of the underground flood was the North Branch of the Chicago River, pouring into a breeched section of an abandoned freight tunnel crossing beneath the river at Kinze Street. The tunnel was part of a 62 mile network of abandoned freight tunnels, originally built in the early 1900s (Figure 1), crisscrossing downtown Chicago and connecting to building basements. Six months before the flood, two dolphin pile clusters protecting the southeast abutment of the Kinzie Street Bridge were removed; the clusters were relocated approximately three feet to the south (unwittingly closer to the tunnel), and new piles were driven (Figure 2 and Figure 3). The tunnel breach was recognized prior to the flood and contracts were already in progress to repair the tunnel.
The Chicago Tribune has many stories about the flood. This article discusses the discovery and failure to correct the problem in time.
Chicago Tribune - The Loop's Great Chicago Flood
One of the biggest shocks of the calamity was that city officials had known about the potential problem--for three months, it turned out--but had moved too slowly to approve the $10,000 contract to fix it. In September 1991, a private contractor had driven new wooden pilings into the river bed next to the Kinzie Street drawbridge to protect the bridge from passing barges and other traffic on the North Branch of the Chicago River. The pilings had been placed in the wrong spot and punctured the ceiling of the freight tunnel below.
A slow leak was discovered in January by cable-TV company workers who were inspecting cables that ran through the tunnel. City officials were notified, but because of bureaucratic hemming and hawing, nothing was done.
WBEZ has a 20 year anniversary article which describes the beginning of the flooding.
WBEZ - The Great Loop Flood
The city was notified about the accident.
Months passed. There was no water leak, so there didn’t seem to be any hurry about fixing the crack. Then, shortly before 6 a.m. on the morning of April 13, the Fire Department received a call about flooding in the basement of the Merchandise Mart.
Had a water main broken? That explanation was soon discarded, as the real problem became evident–the river had pushed open the crack in the freight tunnel wall, and was pouring through.
This next link goes to a 2:51 video with a WMAQ radio reporter, Larry Langford, who re-reads his first report of flooding and his sighting of the whirlpool in the Chicago River.
CBS Chicago - The Chicago Flood: 20 Years Later
This link has 20 photos with captions taken during the flood.
Chicago Tribune photo gallery - Great flood of 1992
The city tried to fill in the hole by dumping truckloads of rocks, cement, and even old mattresses into the river. Each time it appeared to plug the leak, in a short time, the whirlpool would reappear.
Leaked finally plugged by Kenny Construction
Kenny Construction received the call from the City of Chicago and John Kenny, Jr. went to the site to determine the extent of the damage. After surveying the damage Mayor Richard M. Daley immediately requested John and Kenny Construction to lead the repair efforts working hand-in-hand with the City Police, Fire, Public Works and Emergency Services and the U.S. Army Corps of Engineers and the Federal Emergency Management Authority.
The leak was then sealed by drilling 8 shafts into the flooded tunnel near Kinzie Street and placing emergency plugs in the tunnel. Kenny crews then installed a system of flood control doors to stop the leakage and isolate any future floods. Finally a massive pumping system was operated for several weeks to finally drain the flooded tunnels.
It wasn't until next month that the subway was reopened for passengers.
The CTA board voted Friday morning to accept a staff recommendation and begin running trains along the line at 2 p.m.
Chicago Tribune - State Street Subway Running Again