https://dailyhive.com/vancouver/amtrak-suspended-landslide-vancouver-seattle
A double track tunnel or even a trench would be very expensive to build. Thus, an elevated double track line would be better. However, people would likely complain and prefer the current backwater BC situation.
https://vancouver.citynews.ca/2024/12/19/vancouver-seattle-amtrak-rail-service-suspended-landslide/
Backwater BC must upgrade its transportation corridors.
https://globalnews.ca/news/10925862/white-rock-bc-landslide-amtrak-service-seattle/