Liquefied natural gas (LNG) is gaining traction as a substitute energy source in the transportation sector. While presented as a promising energy alternative, LNG also faces criticism for being environmentally unsustainable. This debate has sparked interest from authorities, professionals, and business developers uncertain about the stance to take toward LNG. This study seeks to offer preliminary insights into this issue by investigating the environmental and economic impact of liquefied natural gas on heavy-duty vehicles (HDVs) in Canada. In this country, LNG sources are abundant. A thorough life cycle assessment is conducted on the environmental impact of deploying LNG as an alternative fuel for heavy-duty vehicles in the city of Saguenay, Canada. In particular, an extensive risk assessment is also carried out on the impact of uncertain factors such as policies and markets on the economic benefits of stakeholders by using the Monte-Carlo algorithm. Although the project was eventually canceled in Saguenay and implemented by LNG Canada in Kitimat, British Columbia, Canada, the results show that promoting LNG in Saguenay may yield significant environmental benefits on almost all environmental impact categories, even in the worst possible development scenario. However, it should be noted that the engine's methane emission and energy efficiency both significantly influence LNG's global warming potential. Advances in technology will show more significant potential for environmental preservation. Additionally, appropriate incentives can significantly increase the economic benefits and reduce the investment risk of facilities and vehicles.