It's no secret that the transportation sector is a leading source of GHG emissions in Canada. With mobility demands rebounding from pandemic lows and are projected to grow, the switch to zero-emission, electrified transportation is pressing.Trains are recognized as the cleanest mode of transportation for moving both passengers and goods. Although Canada is not usually known for betting on rail, our governments deserve praise for supporting decarbonizing rail transit projects such as the electrification of the GTA's GO network and the Toronto's subway lines extensions. Canadians need more of these new or revamped inner-city electric transit systems.Regarding inter-city rail, the Government of Canada launched in 2021 the process to create a new dedicated passenger rail connection in the corridor from Quebec City to Montreal to Toronto (and eventually to Windsor). Described as “High Frequency Rail” (HFR), the project would connect cities such as Trois-Rivières and Peterborough with Canada's metropolises, while enhancing on-time performance, introducing more frequent departures and reducing current travel times. Moreover, the new rail infrastructure would provide electric propulsion on more than 90% of the 1,000 km planned corridor. All positive, but the project currently lacks an essential component to make it the must-needed game-changer on Canada's race-to-zero carbon: high-speed.The Federal Government has identified modal shift as HFR's top objective. However, international experience shows that to achieve a significant modal shift from plane or car to train over a Montreal-Toronto-like distance, train travel time must drop below the 3-hour mark. As it stands today, estimated time travel from Montreal to Toronto with HFR is still far from hitting the sweet spot that would drive consequent ridership. In short, at regular speed (160km/h), the corridor is unlikely to ever give Canadians the full bang for their tax buck.Some might argue that demographics, economics, or our mobility “culture” do not support the required investment to implement high-speed in Canada. Well, among other reports and studies, the Regional Plan Association (a New York-based non-profit organization) recently concluded that the Montreal-Toronto corridor is making the top 3 best candidates for high-speed in North America, along with the Boston-NYC-Washington (DC) and the Los Angeles-San Francisco corridors.Others might say that high-speed would only favor direct connections between major cities at the expense of intermediate communities which are also in need of a rail link. However, south of the border, the Amtrak high-speed rail service between Boston, NYC and DC does connect a dozen intermediate-sized localities with major centers, strengthening their links and their development. Not only it is possible to marry frequency and speed, but it is the right thing to do.Finally, some might conclude that Canadians cannot afford high-speed rail and should then prioritize other means to reduce GHG. Let's remind that Canada is the only G7 country and one of the very few G20 countries without high-speed rail. Canada has also the highest per capita GHG emissions among the G20 nations and is the only G7 country whose emissions have increased since signing the 2015 Paris Agreement.Few weeks ago, Transport Canada opened on the possibility of adding high-speed on certain segments of the HFR corridor. Minister Omar Alghabra is now challenging interested parties to propose innovations that would allow reaching 300 km/h speed. These are very encouraging developments.As Canada's national rail manufacturer and given our global experience in inter-city transit, we strongly believe that we have today the opportunity to “get it right” from the outset for HFR. The resources contemplated for the project are scarce, and once used on a regular-speed HFR, the barriers for any subsequent corridor infrastructure projects or adjustments would be increasingly large.Investing today on high-speed rail infrastructure is a forward-looking choice, the alternative of which is to redirect more and more infrastructure funds for airports, highways and roads, with little incentive to change our traveling habits. We all remember the chaotic situation experienced at Pearson and Trudeau airports in the summer of 2022, when Canadians massively regained the need to travel. Now imagine how to better meet mobility needs by 2050. With demography and climate change pressures accelerating, and the zero-carbon deadline less than 30 years from today, it is time for Canada to make high-speed rail the backbone of a broader strategy to decarbonise the passenger transportation sector.Olivier Marcil is Vice President Public Affairs, Alstom Canada