Perfect.

This is Crib trestle bridge of the Columbia & Nehalem Valley Railroad at the McBride Creek, circa 1905. A source: https://www.vintag.es/2017/10/vintage-photographs-of-incredible.html

Which says:

Early timber bridges had their drawbacks. Untreated lumber only lasted about 20 years and locomotives could easily cause the wood to catch fire. Collapses - rare today - were a regular occurrence on logging railroads and there are numerous accounts of train crews that regularly hopped off their slow moving locomotive as it approached a high, untrustworthy trestle, allowing it to cross before they would then run across the bridge and jump back on.

But that's about log bridges generally, not this one. Here's an unhelpful wiki page: https://en.wikipedia.org/wiki/Crib_bridge

There's an engineering saying: "Any idiot can build a bridge that holds a load. An engineer can build a bridge that barely carries a load." It looks like they overbuilt the bridge to compensate for lack of solid engineering.

Not an engineer at all, but I gotta say the random logs going up sideways from the river to support the construction make me nervous.

Assuming they are either nailed down in few places or at least has some slits or something similar, they should be pretty stable. That is until the logs themselves are in good condition.