OTTAWA -- Another downtown tunnel is an option being considered as officials on both sides of the Ottawa River look at the best way to expand and link the interprovincial transit system between Ottawa and Gatineau.

The City of Gatineau believes its population will grow between 26 and 33 per cent by 2051. In a technical briefing to the City of Ottawa Friday, representatives from the City of Gatineau and Gatineau's transit system, the Société de transport de l'Outaouais (STO), say an expanded transit service is needed, particularly when it comes to interprovincial crossings.

Gatineau says there are approximately 200,000 interprovincial crossings a day, 25 per cent of which involve public transit. Gatineau expects to see the number of transit passengers crossing the river to more than double by 2031.

In order to accommodate the increased traffic, a study involving the City of Gatineau, the STO, the City of Ottawa, OC Transpo, the National Capital Commission, Public Services and Procurement Canada, and the Quebec transportation ministry was conducted to determine how best to link Gatineau's transit system to Ottawa's to deal with future growth.

"The long list of partners in this study is testimony to the fact that we're working on the most complex public transit project in Canada. A project unraveling in two cities, in two provinces, in the federal capital," said Gatineau Coun. Myriam Nadeau, who is the chair of the STO's board of directors.

The study examined the viability of each interprovincial crossing, including the defunct Prince of Wales Bridge, and considered an expanded bus rapid transit system, a tram system, and a combination of the two.

The bus-only system was ruled out, as it was deemed insufficient to support the growing needs of the transit system and earlier public consultation in Gatineau widely preferred the tram.

The Portage Bridge was considered to be the most efficient crossing. The others were deemed to be too far away from downtown Gatineau and downtown Ottawa. The Prince of Wales Bridge also presented issues involving capacity at the Bayview O-Train station.

OC Transpo Director of Transit Customer Systems Pat Scrimgeour said at the technical briefing Friday that the capacity issue with Bayview involves not having enough trains to move a high number of STO passengers. He said it would cost tens of millions of dollars to increase the train capacity and added the distance from Bayview to downtown is fairly short, consisting of one addition stop at Pimisi Station before reaching the tunnel at Lyon Station.

STO Director of Development, Marketing and Communications Patrick Leclerc said the Prince of Wales Bridge could still be used in the future as a secondary connection point between the two transit systems, but it would be insufficient in a high capacity scenario.

Aboveground on Wellington or tunnel under Sparks

Two options were presented for running future STO trams in downtown Ottawa: run them aboveground on Wellington Street or run them underground, in a tunnel built below Sparks Street.

Each option was presented with pros and cons. The Wellington Street option would cost less and be easier to build, but officials worried about the potential for protests and other events on Parliament Hill to disrupt the tram service.

The Sparks Street tunnel option is more expensive, riskier, and more complex, but would also have the least impact on aboveground traffic in the downtown core.

Leclerc said there would still be STO buses in downtown Ottawa even after a tram system is built that would cross at both the Portage and Macdonald-Cartier bridges and connect with Lyon Station.

Nadeau said the City of Gatineau does not have any cost estimates for either the Wellington Street plan nor the Sparks Street tunnel plan. Gatineau Mayor Maxime Pedneaud-Jobin said in 2018 that it would cost $2.1 billion to build a rail system in Gatineau, with links at the Portage and Prince of Wales bridges. That figure was used to secure funding from the province of Quebec. Nadeau said Quebec is providing 60 per cent of the cost and talks are underway to secure federal funding.

Public consultations in Ottawa and Gatineau are planned for June of this year, with the goal of presenting a recommended plan to Ottawa's Transit Commission in July, 2020.

Nadeau said the current timeline set aside for the project is eight to ten years.