In the summer of 2015, on a bluff overlooking downtown Calgary, Jason Kenney, then a senior minister in the Conservative federal government, announced a surprise $1.5-billion contribution from Ottawa to help fund a major light-rail transit project called the Green Line.

The price of oil was in free fall, but spirits were high. Ottawa was backing the plan because “Canada’s largest cities depend on public-transit infrastructure,” Mr. Kenney declared. Calgary Mayor Naheed Nenshi spoke of a state-of-the-art LRT traversing the whole of the city, from the distant north to the far southeast. The 46-kilometre line, by far the biggest public infrastructure project in the city’s history, would double the size of Calgary’s LRT system.

Today, that vision is in tatters. The Green Line is another example of how Canada’s system of building transit projects suffers from the vicissitudes of short-term thinking.

Story continues below advertisement

It happens in Toronto, where a Scarborough LRT that could have been finished by now was replaced by a subway whose construction hasn’t even started, and where a Downtown Relief Line under consideration for decades is still at the pre-blueprints stage.

It happens in the Vancouver suburbs, where a smart LRT plan within Surrey was shelved in favour of a lesser SkyTrain extension to distant suburbs.

And now it’s happening in Calgary.

The problems started at the very beginning. In the early 2010s, when federal transit money was scarce, Calgary already knew it needed an LRT on the Green Line route – buses on the northern side were packed and communities in the southeast were underserved by transit.

But Calgary, despite a massive oil boom, didn’t have the money. Cities rely on – and have to beg for – help from higher levels of government. Bus rapid transit was the best interim option.

Then, in 2015, two weeks before the start of the federal election campaign, in swept Mr. Kenney. Ottawa had called Mr. Nenshi four days earlier and had essentially told the mayor, as he recalled it: “Hey, we’re going to write you a cheque, how much do you want a cheque for?’”

The original Green Line LRT budget was $4.5-billion, a back-of-the-envelope estimate. It soon became clear that the project was a lot bigger than the envelope.

Story continues below advertisement

Within a year, the cost to tunnel under the Bow River and downtown was estimated at $2-billion. By 2017, the city realized $4.5-billion would build less than half the Green Line. Still, the province finally showed up with $1.5-billion from Alberta’s new carbon tax, and Mr. Nenshi pledged, “We are going to build something so special.”

Two years later, the city is facing a budget bind, and doubt is being cast on the tunnel plan – a core pillar of the original idea. This fall, Mr. Kenney, in his first budget as Alberta Premier, yanked money away. The province still dangles the possibility of eventually providing its promised $1.5-billion, but not any time soon. In the next four years, just $75-million is on offer. That threatens to further slow construction, while making the truncated Green Line even more expensive for the city.

It’s not easy to plan a big project – a chastened Mr. Nenshi now calls it “monstrously complicated.” Nor is it easy to pay for one. It is definitely not easy to turn a good idea into a successful reality. And it is all the harder to plan and build for the long term, because while these projects need decades-long funding streams, provincial and federal cash runs the risk of being offered, accepted and rescinded over a four-year election cycle.

The Green Line needs to be put back on track. Leadership, from Calgary city hall, the legislature in Edmonton and Ottawa, is lacking. The Green Line vision was always expensive. It was supposed to be a transformative project: top-tier transit infrastructure in Canada’s oil capital. Instead, Calgary is now aiming for something far less.

Final decisions are still pending, and a better outcome is always possible if governments can co-operate and put their heads and pocketbooks together. Mr. Kenney is focused on cutting spending over the next few years, but this is a project whose impact will last for decades.

As for the Trudeau government, it has an opportunity to step in and offer greater backing for something that will deliver more transit and reduce emissions, while reminding Albertans that, yes, Ottawa really is on their side.