Toronto's proposed one-stop $3.2-billion subway extension is indefensible. A city with crushing transit problems cannot afford to waste so much money for so little gain. And yet Mayor John Tory continues to push forward this underachieving megaproject with a small-minded zeal that is distorting decision-making in Canada's largest city.

Mr. Tory is the chief advocate for the six-kilometre Scarborough subway line, which will poorly serve a low-density section of the city better suited to a cheaper light-rail system that would provide considerably more stops. If you care about moving the greatest number of people through the city at the lowest possible cost with maximum efficiency, there is no argument here – the light-rail system is the only way to go.

Mr. Tory doesn't have logic on his side, and so has grown increasingly hostile toward critics who've poked holes in his arguments.

Story continues below advertisement

It's bad enough that he's denounced LRT advocates as ideologues who "fight to move backwards," as if the two sides in the debate weren't simply staking out rival positions for a better, more mobile future. Any delay imposed on the one-stop subway is a necessary test of a scheme that has not proved its benefit to the city at large.

But that's the main problem with the Scarborough subway extension, which is rooted in political squabbles that would be called petty if they didn't come at such a high cost. Rob Ford, the former mayor, insisted the suburbanites of Scarborough deserved the ease and comfort of subways no less than downtowners – as if a half-empty, overpriced subway train were a symbol of social equality and not just a vote-getting machine.

All transit planning should be based on the realities of population density, because underground subway lines are very expensive to build in areas where riders are few.

But Mayor Tory, outwardly less populist than Mr. Ford, continues to push the equity argument in language that is inappropriately divisive. This week he strayed into dangerous territory when he made subtle implications of racism against the subway's critics – on the specious grounds that they didn't want to see $3.4-billion spent in a part of the city where more than half the population was born outside Canada.

Mr. Tory is being needlessly defensive. He should find more persuasive arguments.