If metro Atlanta is a region whose residents reject regionalism — as I argued in this space Thursday — then how are we going to tackle truly regional problems, particularly concerning transportation?

Letting counties band together for specific projects, and giving them more flexibility with local taxes, would be a start. But those measures don’t pack the same punch that the regional, $7.2 billion T-SPLOST would have delivered.

Which is another way of saying: Can we really ask, say, Fulton and DeKalb alone to bankroll a $450 million reconstruction of the I-285/Ga. 400 interchange?

Probably not. But the answer isn’t to try another big T-SPLOST. A second vote might have made sense had the first one not been defeated nearly 2-to-1 last summer. That margin revealed the depth of the flaws in the regional sales-tax model.

The answer is for the state to do what it should have done in the first place, and take the lead.

The premise behind the law creating the T-SPLOST wasn’t that metro Atlanta isn’t the state’s most important economic engine. It was that Republican lawmakers wanted voters to raise their own taxes.

How they get the funding now is up to them; there are a few good options. The most important point is, it’s their responsibility.

Any transportation project of truly regional significance in metro Atlanta is bound to be of statewide significance. Products from other regions headed elsewhere, from Vidalia onions to Dalton carpets, very often pass through Atlanta.

But freight isn’t the only reason our problems are their problems. Moving people through metro Atlanta matters elsewhere, too, both directly — tourists stuck here en route to our Golden Isles — or indirectly — businesses reluctant to move or expand here, and boost the state economy, because they’ve heard about nightmare commutes.

Likewise, our solutions may yield benefits for them, too. Economic over-reliance on metro Atlanta is not good for the state in the long run. Anything that diverts traffic from here — say, a western bypass incorporating U.S. 27 — can bring a balancing growth to other parts of the state.

There is a potential slippery slope here: What qualifies as truly regional, and thus a matter of state concern? Does MARTA qualify?

That question could, and will, merit another column. The short answer is deeper state involvement in mass transit should lead to a truly regional, preferably privately run model. That might mean a bus rapid transit or commuter rail system, operated across multiple counties, on existing or improved (that is, not built new from scratch) infrastructure, by a private vendor with a state contract.

This state-led approach mirrors the one Gov. Nathan Deal championed once the T-SPLOST failed. But there must be more money for transportation than is now available. Which is not the same thing as higher taxes.

One option is to shift the fourth penny of the sales tax on motor fuel from the general fund to dedicated transportation funding over time. That move would have the added benefit of maintaining spending discipline as the economy recovers, revenues rise — and legislators are tempted to spend the dough on other things.

Use that money to attract and leverage private investments, and we could be on a much faster and smarter road than the regionally bound T-SPLOST could have paved.