I think this is the quote that is most relevant

> En kombinert stålbjelkebru med betongdekke var mulig, men ble utelukket på grunn av estetikken og begrensningene i veigeometrien under og på brua.

which states that aesthetics and road geometry together ruled out a combined steel and concrete bridge.

there's also:

> Artikkelen beskriver avslutningsvis at det i pre-designfasen var flere retningslinjer knyttet til utformingen av brua. Videre står det at teamet som prosjekterte brua ble påvirket av andre prosjekter på den aktuelle tiden, og at Oppland fylke var et skogsbruksfylke der tre har vært et viktig byggemateriale. Dette, kombinert med fordelene av det lette dekket, medførte at en trebru var det beste alternativet. Kombinasjonen av tre og stål gjorde det også mulig å utforme brua som ønsket, uten ekstra avstivning ved aksene.

But in the end the above just amounts to "they could have built a conventional bridge but wanted something prettier": basically aesthetics contributed to the collapse because it was the primary reason they built something novel.

Had there instead been some site specific geometry that forced a novel solution, one wonders if they had blamed that...

Well, either would work: Steel can be easily fitted to take tension loads; Or the wood could be oriented to be in compression, with the ends butted against other structure thus relieving the bolts of most of the load.

Here's one that combines both techniques:

https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2F...

What was done instead concentrated the tension stress onto a small central core section of the member, with rest transferred to wood grain-aligned, therefore weak, sheer faces within the timber.

Thanks for the video: To anyone who's spent some time working with wooden garden gates, that's enough to tell the story.