Want to fix the T? Don’t forget to pay for it.

Passengers squeezed onto a bus during the morning commute at the Quincy Adams MBTA station Wednesday.David L. Ryan / Globe Staff/Globe Staff

Perhaps it's too much to expect any transit system to run smoothly with a once-in-a-century pileup of snow. But the recent delays and derailments have drawn attention to some of the deeper problems of the T, including aging cars, outdated equipment, and a longstanding lack of investment.

Momentum seems to be building for a new commitment to make transit work, but it's worth remembering that we've tried this before — and not that long ago. Toward the end of his tenure, Governor Deval Patrick proposed a major new investment in transportation. But by the time his plan became law, it had been starved of nearly all funding, leaving behind a commitment to improve transit without a sure way to pay.

What did Governor Patrick propose?

Early in 2013, Governor Patrick unveiled a big package of investments in transportation, among other areas. Every year, the state would have over $700 million in new transportation funding to address some of the major problems with our roadways and transit systems, including aging bridges, subway cars well past their normal lifespan, and an extension of subway and rail lines into poorly served regions.

And because the money would have been available each and every year, it could be diverted to help with more urgent priorities should they arise.

How did the governor want to pay for this?

With a $2 billion tax package, including an increase in the income tax rate and a drop in the sales tax. So whether or not you like the idea of raising taxes to make new investments in education and transportation, at least the terms were clear: Pay more, get more.

What happened to the governor’s plan?

The Legislature didn't embrace the governor's tax package, but they did support the need for new transportation improvements. So they found a different way to pay for them, including two smaller tax increases. One of those was an increase to the gas tax and another was a tax on certain kinds of custom-designed computer software.

What happened next?

Quite quickly, it became clear that the tax on computer software was extremely unpopular, and probably bad policy. So it was repealed. But the transportation investment wasn't explicitly scaled back.

Then last fall, a ballot initiative reduced the amount of money coming in through the gas tax, cutting out another leg of the transportation funding stool.

So far, the Legislature has been able to cobble together enough to pay for the first few years of new transportation investments. But without a dedicated funding resource in place, funding for T improvements will be at risk every year.

Will the plan still help?

As you may have noticed this week, the investments haven't seemed to cure the T's ills. There are a couple of reasons for that:

1. It has only been 18 months since the budget with the transportation improvements was signed.

2. Those improvements phase in over time, so the additional funding has so far been quite small.

Of course, it's also possible this approach isn't sufficient. Maybe fixing our transportation woes requires even larger investments, or maybe it's not money but mismanagement that's the heart of the issue.

So where does that leave us?

Faced with mountains of snow and stopped subway cars, calls for action are echoing again. But if we want a durable solution, it's important to remember why the T system has degraded over time. It's one thing to agree that something must be done, and quite another to provide the resources to ensure it gets done right.