Gubernatorial rivals Jay Gonzalez, left, and Charlie Baker.

DEMOCRATIC GUBERNATORIAL CANDIDATE Jay Gonzalez released what he called “a secret state document” just prior to Thursday night’s debate with Gov. Charlie Baker that he said raises questions about the MBTA’s ability to bring its equipment into a state of good repair in 15 years and its long-term spending plans.

The document – a June 2017 report to the Federal Transit Administration on the Green Line extension – has been talked about in hushed tones in transportation circles for some time, but it’s hardly secret. The Federal Transit Administration has copies and the Department of Transportation provided a copy to CommonWealth in September when the magazine asked about it.

What’s most surprising about the document is a chart forecasting capital spending at the T. The spending rises from $783 million in 2017 to $1.8 billion by 2021. In 2022, capital spending declines slightly to $1.7 billion, but then falls off a cliff, dropping to $868 million in 2023, $620 million in 2024, and $517 million in 2025.

The implication is that the big, five-year, capital spending push Baker trumpets at every turn will dry up after 2023. Many transportation advocates have said the document suggests the state will need to find new sources of money to carry out its capital spending plans beyond five years.

But state transportation officials insist the chart is structured the way it is because of federal reporting rules. They say the Federal Transit Administration allows transit agencies to include in their capital spending forecasts only committed funds. Since Massachusetts makes capital spending commitments for only the next five years, the numbers in the report don’t include state and local funding sources that haven’t been committed yet. What’s left are estimates of federal funding (which are forecasted to grow more slowly in the future) and savings from operations.

State officials pointed out that the Legislature has appropriated money for the T every year since 2000, but that money wasn’t included because it isn’t committed years in the future.

At the debate, Gonzalez focused most of his attention on another element of the report that suggests it will take 25 years, not 15 years as Baker has insisted, to bring the T into a state of good repair. “It turns out that’s not even his plan,” Gonzalez said.

Baker stood by his 15-year estimate, saying the T has upped spending so much on state-of-good-repair work over the last two years that the 25-year estimate has been reduced to 15 years.

Bruce Mohl oversees the production of content and edits reports, along with carrying out his own reporting with a particular focus on transportation, energy, and climate issues. He previously worked...