(New York, NY - WNYC) Expect delays. That's the message from the New York Metropolitan Transportation Authority as it readies to spend $2 billion in federal relief aid to make repairs to the subway after Sandy.

Flooding from the storm coated thousands of electrical components in parts of the system with corrosive salt water. The MTA says riders can expect more frequent interruptions of service as those switches, signals, and other parts are replaced.

Immediately after Sandy, the MTA scrambled to get the subway up and running, sometimes with components that were damaged by flooding but hastily cleaned and pressed back into service. Much of that equipment is functioning with a shortened life span, and will be replaced.

That means a lot of repair work will be happening in the subways over roughly the next two years. MTA executive director Tom Prendergast says the work will cause more line shutdowns, called "outages."

"The problem we're going to have is how do we do that and keep the system running?" he told members of the transit committee at MTA headquarters in Midtown Manhattan on Monday. "We don't want to foolishly spend money; we want to effectively spend that money in a very short period of time. So there are going to be greater outages."

Except for the still-shuttered South Ferry terminal and severed A train link to The Rockaways, the subway was almost entirely back up and running within a month after the late October storm. But Sandy's invisible fingers, in the form of corrosion, can still play havoc with trains.

MTA spokesman Adam Lisberg said, "The subways have recorded more than 100 signal failures related to Sandy since service was restored after the storm, plus problems with switches, power cables and other infrastructure. Most of those failures happened in yards, but some were on mainline tracks and led to at least short service disruptions."

Twice last week, signals on the R train failed and briefly disrupted rush hour service. The problem was traced to components degraded by salt water caused by flooding in the Montague Avenue tunnel, which connects Brooklyn to Manhattan beneath New York harbor.

The MTA is in line to receive $8.8 billion in federal Sandy relief aid, which is to be split about evenly between repairs and hardening the system against future storms. Projects funded by the first $2 billion must be completed within two years after their start date. That will cause a flurry of repairs in large swaths of the subway--mostly in Lower Manhattan, the East River tubes, and lines serving waterfront areas of Brooklyn.

The MTA already shuts down or diverts train traffic from parts of the system on nights and weekends to upgrade tracks, signals and switches, and otherwise keep the subway in "a state of good repair." Add to that the new Fastrack program that closes sections of lines overnight for several days in a row, allowing work gangs to fix tracks and clean stations without having to frequently step aside for passing trains. And now comes even more disruptions in the form of post-Sandy repair and mitigation.

There's no word yet on when work will commence or on what lines the extra outages will occur, but straphangers would do well to start bracing themselves. Sandy wounded the subway to a greater extent than the eye can see, and it will take years--and extra breaks in service--to return the system to its pre-storm state.