When TTC commissioners ordered yet more studies on subways to Scarborough last week, reaction was swift and severe. After all the back and forth over transit in the past couple of years, said Councillor John Parker, it was "a stupid, stupid, irresponsible thing" to reopen the transit question. The Toronto Star called it "a move that will leave transit-starved Torontonians gnashing their teeth in frustration." Councillor Josh Matlow said it was nothing less than "folly."

Just months ago, after all, city council concluded a furious transit debate by overruling Mayor Rob Ford, voting down his confused plan for a Sheppard subway and opting for a network of light-rail lines. Now the commission has asked staff to look again into the feasibility of putting in subway service to central Scarborough.

That is not as nutty as it first sounds. Take a look beyond the flaming rhetoric to what is actually on the table. Under a proposal by TTC vice-chair Glenn De Baeremaeker, most of the LRT network would remain as is, with lines along Sheppard, Eglinton and Finch. He proposed one major change: Instead of replacing the outmoded Scarborough rapid transit line with a light-rail line along the same route, he would build a subway connecting the Bloor-Danforth line to the Scarborough town centre.

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This has a couple of big advantages. To begin with, commuters could travel all the way from the town centre to the Yonge subway line in one trip. Under the existing light-rail plan, they would have to transfer at Kennedy station, as they do now from the RT. An uninterrupted trip would greatly simplify the trip from Scarborough to downtown and back.

Second, building a subway would avoid years of interrupted service. As it stands, the Scarborough RT will have to be shut down and completely rebuilt to allow for the new light-rail vehicles. That would probably take at least three years, leaving Scarborough commuters scrambling. A subway would be built along a different, more easterly route, so the Scarborough RT would keep running until the new line is completed.

Yes, a subway would be more expensive, but not ruinously more. While estimates vary, Mr. De Baeremaeker puts the extra cost at around $500-million, against the price tag for the whole light-rail project of $8.4-billion. A subway could carry more people in the future, he says, while the light-rail route would be near to capacity as soon it opens.

What is more, says the councillor, who represents Scarborough Centre, a subway would integrate populous Scarborough with the city centre. "There is a feeling of discontent in the east end," he says. "I don't think people downtown can understand the visceral feeling that we have been ripped off." Mr. Ford tapped into that feeling when he proposed a Sheppard subway, but the cost was enormous – around $3-billion – and he had no credible plan for financing it.

Mr. De Baeremaeker's critics says he is only trying to save his own hide, signaling to constituents that, just because he opposed Mr. Ford's Sheppard subway, he isn't trying to deny them their subways. He naturally denies it. He is backed in his bid by the capable TTC chair Karen Stintz, who is from North Toronto.

They didn't pull the idea out of a hat. Transit planners have often mulled replacing the Scarborough RT with a subway. Mayoral candidate George Smitherman proposed it in 2010. So did Sarah Thomson.

Whether the idea goes anywhere is an open question. Queen's Park says it is fed up with all the talk and wants to get on with the light-rail project. But construction isn't starting for a couple of years, and reconsidering one part of it doesn't mean throwing out the whole thing. With so much at stake, taking one more careful look at the possibilities isn't folly. It's sober common sense.