A tunnel that would connect the Macdonald-Cartier Bridge and Highway 417 and potentially reduce truck traffic in downtown Ottawa is "technically possible" but could cost up to $2 billion to build, according to the results of a feasibility study released Wednesday.

The $750,000 study, funded equally by the City of Ottawa and the province, concludes that a two-lane, 3.4-kilometre tunnel could be constructed underneath the city's Lowertown and Sandy Hill neighbourhoods.

The "most feasible alternative" would see the tunnel head east from the Macdonald-Cartier Bridge, cross King Edward Avenue and angle southeast under Lowertown. It would then run parallel to the Rideau River from near Laurier Avenue to Main Street before crossing the river and emerging at the Vanier Parkway/Highway 417 interchange.

Rideau-Vanier Coun. Mathieu Fleury, whose ward includes many residents who have long complained about large trucks rumbling through their neighbourhoods, said people are "ecstatic" about the study's findings.

Happy to share that a tunnel between the Macdonald-Cartier Bridge and the 417 is possible <a href="https://twitter.com/hashtag/safety?src=hash">#safety</a> More details here <a href="https://t.co/cUZPcCx5IY">https://t.co/cUZPcCx5IY</a> —@MathieuFleury

"We're not pushing the issue onto another community. We're resolving the issue, creating a connection from the bridge onto the 417, removing those interprovincial trucks from our downtown streets," Fleury said.

"This removes the safety concerns that we had, the pollution concerns, and certainly the economic development challenges that we see along that corridor."

Up to 25,000 vehicles a day

The proposed tunnel would carry between 20,000 and 25,000 vehicles per day, and would not be limited only to trucks — mainly because the traffic demand would be "too small" to justify a truck-only tunnel, the city said in a media release.

The proposed two-lane, 3.4-kilometre tunnel could be built under Ottawa's Lowertown and Sandy Hill neighbourhoods, according to the study. (City of Ottawa)

Of those vehicles, approximately 1,700 would be trucks, the study concluded. Data from 2011 included in the study found that approximately 2,600 trucks crossed the Macdonald-Cartier bridge during a 24-hour period, but not all of those trucks would need to — or be able to — use the tunnel.

"Thirty-five per cent of truck traffic currently using downtown streets would not use the tunnel because they need to make local on-street deliveries or pick-ups," the city said. "Furthermore, any trucks transporting dangerous goods would be prohibited from the tunnel due to safety concerns."

The preliminary cost estimate for the tunnel is between $1.7 and $2 billion, according to the study. Shorter and potentially less costly tunnel alignments were considered, the study notes, but ultimately rejected due to a number of issues, including how the tunnel would interact with future urban development, the University of Ottawa, and the forthcoming Confederation light rail line.

NCC rejected bridge

The findings come three years after the National Capital Commission pulled the plug on an environmental assessment of what would have been Ottawa-Gatineau's sixth interprovincial bridge.

The NCC had hoped a new bridge crossing at Kettle Island would reduce the volume of truck traffic coming across the Macdonald-Cartier Bridge from Gatineau into downtown Ottawa. But the proposal was scuttled after the Montfort Hospital suggested its construction could cost lives and the Ontario government refused to support it.

If the tunnel proposal is given the go-ahead, future steps would include carrying out an environmental assessment and geotechnical analysis, as well as coming up with a plan to fit the tunnel into the "broader transportation planning processes being considered for the National Capital Region," the study said.

Both the tunnel study and a staff report will now be discussed on Sept. 7 when the city's transportation committee meets.