The MTA is at least five years away from implementing its new fare payment system. Meanwhile, it has to keep the MetroCard limping along.

The agency says maintaining its MetroCard system is becoming too expensive, and that by 2019, the yellow plastic fare cards will be at the end of their useful life.

Besides, said MTA spokesman Adam Lisberg, "the MTA wants to get out of the business of issuing the fare payment mechanism."

The agency is about to issue a request for proposals for its next generation fare payment system, and while it doesn't know what it will look like, one hope is clear: you may already own it. People want to be able to pay with things like phones and credit cards, said Lisberg, "and we want to be able to adapt to what customers want." Riders could, for example, pay by holding up a bar code displayed on their smart phones. Or tapping a credit card with a chip in it.

But the new system, which is expected to cost $450 million, won't be ready until 2020. The MTA couldn't immediately provide an estimate for how much it will cost to maintain the MetroCard past 2019.

Meanwhile, the agency is working on the system's back end, installing the fiber cable necessary to provide software support for the system.

Retrofitting the system's 468 subway stations is nothing new. "When we first put in MetroCards," Lisberg said, "we had to wire some stations for electricity, because previously they'd taken power for the lights off the third rail."