After all these decades, planners are only now realizing that BC is notorious for heavy rain at times.
Its not that the Trans-Canada_Highway in SW BC had to be all elevated through the Fraser_Valley_Regional_District. but it should have been on built up land.
https://globalnews.ca/news/8417722/abbotsford-bc-flooding-latest-evacuations/
https://en.wikipedia.org/wiki/British_Columbia_Highway_1#Lower_Mainland_section
"The Interior section of Highway 1 is considered sub-standard when compared to other highways with similar traffic volume in the U.S. or other parts of Canada." https://en.wikipedia.org/wiki/British_Columbia_Highway_1#Future
However, the inept highway has met the sub-standard requirements of BC for several decades.
https://en.wikipedia.org/wiki/British_Columbia_Highway_1_between_Hope_and_Yale Just having the paved over equivalent of 2 wagon-roads was challenging enough for BC to attain.
Its difficult for BC to achieve a quality similar to that of Alberta, Ontario or Quebec...
https://dailyhive.com/vancouver/aerial-look-jackass-mountain-highway-1-closure
The mountains in Switzerland don't prevent good highways from being built.