Myths about the Viaducts #3: “Leave them alone, they’ll last forever.” Nope, they’ll fall at the first tremor

Myths about the Viaducts #3: they’re built for the ages, can never fall down

A recent Vancouver Courier story cited comments from a former member of Vancouver’s engineering department claiming that the viaducts are perfectly fine, as well as that a 2009 city staff report that showed that the viaducts were in good condition. Yes, they are fine, but not in an earthquake.

The Georgia and Dunsmuir Viaducts: part of Vancouver's future or relics of a project the city rejected?

Strongly built, but built on soft foundations: they would not survive an earthquake in their current state.

That 2009 report was a preliminary analysis, and done long before this spring’s announcement that the province intends to move forward with a new St. Paul’s Hospital in the False Creek Flats. This triggered a more detailed seismic analysis done this spring, all of which is posted publicly and you can read here. With the new St Paul’s Hospital in the Flats, the city needs to ensure that the viaducts go above and beyond seismic standards to ensure they are usable during an earthquake. The results of that third-party analysis? That the viaducts aren’t even close to being at that level, and would require an estimated $65 million to bring up to code.

The bad news: with the upgrade, they might not fall down in an earthquake, but they would probably be unusable.

As for the former engineer’s claim about traffic concerns, the city staff traffic analysis and impact studies are all posted on the city’s website. I trust those reports more than someone who left the city seven years ago. The Viaducts currently carry only half of the car traffic for what they are designed for, and the new two-way road along Pacific would have the same capacity as today’s system, with better connectivity.