Covered wooden bridges last hundreds of years and they are very beautiful. Maintenance is required (as with everything) but life cycle cost is really good especially for shorter spans.
Down in Tasmania there are thousands of tonnes of flooded forest woods, which are being dredged up 50 or 60 years down in the cold dark dam-water, and being turned into exquisite furniture and musical instruments. I'm told almost petrified Kauri Pine can be the same, other woods turn into something magical when left alone for a long time. Put GluLam to the same test, It's probably not happy outcome.
Good story about the Kauri Pine, that looks like a pretty cool tree!