It's looking more and more likely the Green Line LRT will go underground through downtown Calgary.

The transportation and transit committee was told the underground option is ranked higher than four other options, as an elevated line could lower property values downtown.

The city is examining five possible routes for the Green Line to get from 20th Avenue North over or under the Bow River through downtown — using elevated, street level or underground sections — before finally making its way to the Beltline. ​

The full-tunnel route would see the LRT line run underground from 20th Avenue North all the way south to the Beltline in a tunnel beneath both the Bow River and downtown Calgary. (City of Calgary/Screenshot)

In April, the city said digging a tunnel underneath Crescent Heights, under the river and all the way under the city core at Second Street — at an estimated cost of $1.8 billion — has been identified as the best option.

The other options under consideration are building a new bridge to carry LRT cars over the Bow River, then either carrying the line above grade over downtown, or building a shorter tunnel below the city centre.

Those options were believed to be roughly $500 million less than the full-tunnel option.

Property values ​

Richard Morden, a property manager with Bentall Kennedy, said the company's clients want the LRT to go underground along Second Street S.W.

To get through the city core along Second Street S.W., the new C-Train could go underground, at grade, or be elevated, as shown. (City of Calgary)

He told councillors an elevated line would hurt land values, resulting in a loss of nearly $5 million per year in property taxes — not to mention the effect on street life.

"It's essential to maximize sunlight, retain pedestrian activity, keep animation at street level so that retail and restaurants do not suffer, and that of course means an elevated guideway is our absolute worst, worst choice in terms of vibrancy for the core," he said.

He also pointed to undeveloped sites that will be affected if an elevated line is built.

"The all-tunnel option is the best," said Morden.

Finalizing the route

The cheapest option under consideration is to run the LRT line down the middle of the existing Centre Street Bridge, pegged at about $700 million less than the full-tunnel route.

An artist conception of the Centre Street-option for the LRT to get across the river. (City of Calgary)

City council will make a final decision on the downtown alignment in September.

The Green Line's route through the Beltline is still to be determined and could include underground, street-level or elevated routes on 10th Avenue, 11th Avenue or 12th Avenue in the city's south.

That section will, in turn, connect with the southeast portion of the Green Line, which is further along in the planning process and has a set route.

The committee also recommended council move ahead on land acquisition along the entire route.

The mega-project will ultimately see a new C-Train line stretch 40 kilometres across the city, from North Pointe to the southeast community of Seton.