City officials will examine a number of different routes the proposed downtown tunnel could take over the next few weeks, and hopes to have options to present to the public in early January, says the tunnel project lead.
vironmental assessment of the proposed light rail transit system, which is scheduled to be completed early 2010.
The assessment will look at different alignments, different types of tunnels that could be used, and construction technologies, says Gratton.
“At the end of the day, we’ll be using the most efficient, most cost effective [option],”he says.
While concern has been raised over the future of the LRT because of its high construction cost, the assessment on the tunnel will proceed, no matter what decision comes out of city hall.
All possible options between Sparks and Laurier Streets are being considered. The tunnel, which will likely be five or six stories deep, could run parallel under the existing streets, he says.
Other alignments could veer across intersecting streets, in what Gratton calls the cross country route. The tunnel could begin on Albert Street, veer under Metcalfe Street and complete its journey under Queen Street.
Other possible options include construction of two separate tunnels – such as having one tunnel under Sparks Street and another under Queen Street, and have both tunnels link up near the exit.
“Double tunnels [running side by side] are certainly very popular right now, because they’re less expensive,” says Gratton. He says since less waste is created less waste needs to be removed.
Another option would be to stack two tunnels one on top of the other, he says.
However, Abd El Halim, chair of the civil and environmental engineering department at Carleton University, says that while this option is not impossible, it is more time consuming (because both tunnels must be built separately), and more expensive.
“[Having] them at the same elevation would simplify a lot of things,” says Halim. This, he says, is partly because when a train leaves the ground, the slope of the tunnel should be no greater than four degrees. Any steeper and the train might not be able to pull its own weight.
However, Gratton says that none of the possibilities have been ruled out yet.
“I don’t think there is one clear winner,” says Gratton.
He adds that the city is currently in consultation with local businesses, the public, and agencies – which include utility companies, city, provincial and federal employees.
Hume Rogers, head of the Downtown Coalition – a group of downtown businesses who have supported the implementation of the tunnel – says that a number of location have expressed interest in linking up with the tunnel; regardless of which route is chosen.
“It would be a great convenience to their tenants,” says Rogers. “And over time, [we] could see, an eventual development similar to the Toronto path system.”
Rogers says that while the development of a new underground city – much like in Toronto or Montreal – won’t be apparent when the tunnel is first opened. It could develop progressively throughout the next century.