Metro General Manager Paul J. Wiedefeld. (Cliff Owen/Associated Press)

As Metro General Manager Paul J. Wiedefeld rallies the Washington region to provide $15.5 billion in long-term funding, what’s lost in the debate is that the money is only enough to cover the agency’s most critical capital needs.

What’s missing is funding for projects and service that aren’t deemed safety-critical but are important for system reliability and function — things that impact riders on a daily basis. There’s no money, for example, for construction of a new Rosslyn tunnel to ease congestion on the Orange, Blue and Silver lines or for a long-term fix for the chronic water leakage on the Red Line that causes dozens of smoke and fire incidents — and service disruptions — each year.

Wiedefeld’s proposal to cap growth in the annual subsidies D.C., Maryland and Virginia contribute for operations at 3 percent does not allow for the extra expense of running service on Phase 2 of the Silver Line, reducing train headways or reviving late-night service.

At a meeting of the Metro board’s finance committee last week, Wiedefeld sought to manage expectations. The $15.5 billion, he said, would be used to make fixes he considers nonnegotiable for the safety and core operations of the system: upgrading its power system to allow for increased use of eight-car trains, replacing deteriorating bus garages, replacing and rehabilitating elevators and escalators that are reaching the end of their useful lives, rebuilding tracks that went untouched during SafeTrack, and paying for new trains to replace the decades-old 2000- and 3000-series cars. “These projects cannot be in jeopardy, because in my estimation these projects are keeping the system safe and reliable,” Wiedefeld said. “This pretty much has to go forward.”

Without the items on this list, Wiedefeld said, there will be dramatic consequences for riders over the course of the next decade — a system that returns to the chronic safety and reliability problems of recent history.

“Think of the last five-plus years,” Wiedefeld told reporters matter-of-factly. “And think of that getting worse and worse.”

He also warned the list does not include a number of projects many people say are critical to the growth of the region — projects that are estimated to amount to another $9.5 billion in capital costs.

For example, the construction of a long-discussed second Rosslyn tunnel, an additional train connection under the Potomac that would relieve a bottleneck that causes delays on three lines, is not on the list.

Likewise the $15.5 billion would not allow for extensive work to permanently fix water infiltration problems in the troublesome stretch of the Red Line tunnel near Friendship Heights, excavation of new Metro station entrances to relieve crowding, or permanent upgrades to the limping station ventilation systems.

Metro board member Anthony E. Costa expressed confusion. Were those costs Metro didn’t know about, he asked Wiedefeld at the board meeting, or simply expenses the agency anticipated but hadn’t prioritized?

“A little bit of all the above,” Wiedefeld said.

Some eyebrows were raised. Wiedefeld said there are no detailed cost projections for such projects, because, for example, a second Rosslyn tunnel isn’t considered among the most pressing safety needs.

Though Wiedefeld’s board presentation was supposed to be just a broad preview of the more detailed operating budget he will present this fall, he offered some details on what else would be considered “extra” expenses on the operations side.

As part of his attempts to bargain for long-term dedicated funding to finance Metro’s capital needs, Wiedefeld proposed capping the annual growth in contributions D.C., Virginia and Maryland are asked to pay each year to help cover the cost of the day-to-day operations.

His proposed 3-percent cap, along with cost-cutting measures and increasing revenue, are an effort to ensure the jurisdictional subsidies grow only enough to approximately match inflation each year.

But that doesn’t cover the many expenses that loom in the near future — such as operating Phase 2 of the Silver Line or paying for station managers and security at the new Potomac Yard station that is scheduled to open in Alexandria in 2021.

When board member Michael Goldman raised concerns those costs were not incorporated into the agency’s planning, Wiedefeld said budget projections hadn’t been made that far out yet so costs were unknown.

“We just want to raise the flag,” Wiedefeld said, “So people don’t think ‘Okay, the Silver Line’s coming, that’s in the 3 percent.’ . . . It will be a new cost that can’t be [roped] in the 3 percent cap.”

Another point of concern is anticipated wage increases for workers. Metro and its largest union recently reached an impasse in contract negotiations and are entering binding arbitration that could result in automatic pay increases or unexpected benefit costs.

Those potential costs won’t be reflected in the upcoming budget proposal, Wiedefeld said.

It was a harsh reality check for the Metro board and for the public: Even if Wiedefeld and the region’s leaders somehow manage to wrangle $15.5 billion for the system in the coming years, riders will still only receive the bare basics of rehabilitation, renovations, and investment to ensure Metro can continue to get by at its current size — not expand.

Some, like Metro board member Christian Dorsey, are concerned about what’s already being left on the cutting-room floor.

“This in no way reflects what I’d love to see Metro become, and that’s my big worry,” Dorsey said. “When it comes time to making that ask [to pay for additional capital funding], will people think that they have nothing else they need to contribute? It’s a big fear.”

Dorsey added growing the system — not merely maintaining what exists — is critical in a region where so much development and investment are dependent on transit.

“I would guess that everybody at this table envisions our system growing to not only meet future needs, but to induce future needs — meaning another river crossing, meaning maybe extending lines, maybe connecting lines,” Dorsey said. “And the danger that we’re having such a huge lift to get to where we have to be means, will there be fatigue in the region when we then come and say, ‘Well, this is where we’d like to be?’ Will people say, ‘No, we’ve already done enough?’ ”

Wiedefeld defended the decision to not promise increased service given the realities of the budget situation.

For too long, he said, Metro officials ramped up bus and rail service without coming up with a long-term plan for how to pay for them.

If officials want longer hours, or more frequent trains, or new bus routes — or a fully-functioning western end of the Silver Line — then the jurisdictions will need to find a way to pay extra.

“We cannot assume it’s somehow taken care of in the existing budget,” Wiedefeld said.