The city of Montreal will spend $3,800,000 to install giant, block-long inflated pergolas along Ste. Catherine St.

The design, by Kanva Architecture, resembles a large white tempo except it's full of holes.

Designers said the idea is to provide the impression of walking along a corridor with a vaulted roof, similar to a large church, while still being able to see the stores on either side.

"The fact that it's visually strong, it will attract people," said Tudor Radulescu.

Each inflatable, known as an Imago, would be about ten metres high, rising to the third floor of the buildings on the street, 14 metres wide, and stretch the entire length of the block.

The owner of Kanva Architecture says it's an innovative design that has never been tested in any city in Canada.

"I think the businesses will thrive in that time rather than struggle and suffer to survive," said Radulescu.

The contest to determine the best idea cost $170,000, and Kanva will get $800,000 for its concept.

The inflatable structures, and the cost to move them, is estimated at $2.8 million -- for a total cost of $3.8 million.

City officials say the inflatables will be used to cover Ste. Catherine St. -- which will be off limits to vehicles-- starting in late 2017.

Officials picked the inflatable tunnel from five finalists in a competition to attract customers to Ste. Catherine St. while it undergoes construction, in an attempt to avoid the economic downturn created by years of construction on St. Laurent and St. Denis.

The four-year plan to revamp Ste. Catherine St. is scheduled to begin in January 2018 and last until 2022.

The last estimate, in 2015, called for construction to finish by 2019 and cost $95 million as decrepit sewers and water mains are replaced, and other problems under the commercial artery are repaired.

City officials say the work is unavoidable and cannot be delayed.

The tipping point for many was three years ago when a sinkhole swallowed a backhoe on Ste. Catherine St.

The overall plan calls for wider, heated sidewalks on Ste. Catherine St., with one lane for cars, two lanes of parking, and one lane for bicycles.

Montreal wants to embed tubes with liquid anti-freeze below the sidewalks, which will be heated electrically.

More than two kilometres of Ste. Catherine St. will be renovated in two phases, first between Bleury St. and Mansfield St, , and then between Atwater Ave. and Mansfield St.

Montreal is examining the possibility of having crews work 24 hours per day, 7 days a week on the project.

The plan is still in development, and over the next few months Montreal will solicit offers for technical studies to determine how feasible heated sidewalks are, and how much they would cost.