It's one of the biggest challenges facing the Metropolitan Transportation Authority: where to find billions of dollars for new track work, new buses and trains, and other projects needed to improve the transit system. A new report titled "Keeping New York on Track" highlights why advocates think the need is so urgent. NY1's Jose Martinez filed this report.

They're the guts of a system that keeps millions of New Yorkers moving daily: the tracks, the signals and the trains.

Maintaining and expanding the city's transit lifeline with projects like the Second Avenue Subway line will cost billions, but the funding is no sure thing.

"There's not enough of a focus on the importance of the MTA to the region and how the region's performance to date would not be possible without the prior capital programs," says Jordan Hare of HR & A Advisors.

The MTA says it needs $32 billion to bankroll its five-year Capital Program. It's lined up some of the money, but is still $15 billion short.

On Wednesday, business leaders and two advocacy groups called for full funding.

"Our goal in this report is to boost awareness of the benefits that have resulted from capital investments programs in the past, to help people understand as we move forward with this program what it means for the region's future," Hare says.

Failing to pay for all the improvements could mean an even slower rollout of new signal technology that allows more trains to run per hour, and eases overcrowding.

It could also mean a delay in building the next second phase of the Second Avenue Subway—or worse.

"Listen, if you knew New York in the 1970s and early 1980s, we cannot go backward. We've made a lot of progress. The subway system is pretty good. But we need to invest in order to keep it good and make it better," says Janno Lieber of World Trade Center Properties.

One way the MTA has helped bankroll past Capital Programs is through extensive borrowing, racking up a debt of more than $34 billion dollars in the process. As any credit-card holder will tell you though, there's only so far borrowing can take you.

"We have been putting capital investement on our credit card and that that's not a viable long-term strategy," says Joan Byron of the Pratt Center for Community Development.

"You borrow money, you 've got to pay it back," says Gene Russianoff of the Straphangers Campaign. 

The state has billions of dollars in surplus funds. Advocates hope the governor and legislators divert some of the money to transit funding in the new state budget, due in april.