Carbon River Fairfax Bridge - Closed

The NTSB report on the Fern Hollow Bridge collapse in Pittsburg made the remarkable assertation that "rust makes metal weaker".


It seems that the State of Washington has been conducting a peer review test of this assertation, and has independently confirmed that indeed rust does make metal weaker.

That will take pressure off the understaffed park.

MintJulep said:

It seems that the State of Washington has been conducting a peer review test of this assertation, and has independently confirmed that indeed rust does make metal weaker.

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Oh my Gosh.
Have we been doing it wrong for all these years?

davidbeach said:

That will take pressure off the understaffed park.

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Maybe this will divert some funding and increase labor ability for infrastructure management.

MintJulep said:

The NTSB report on the Fern Hollow Bridge collapse in Pittsburg made the remarkable assertation that "rust makes metal weaker".

Pittsburgh bridge collapse - Engineering Failures & Disasters

thread815-491466 NTSB to other bridge owners: "Rust makes metal weaker." https://www.cbsnews.com/pittsburgh/news/ntsb-fern-hollow-bridge-report-review-bridge-inspection-reports-nationwide/

www.eng-tips.com

It seems that the State of Washington has been conducting a peer review test of this assertation, and has independently confirmed that indeed rust does make metal weaker.

SR 165 Carbon River Fairfax Bridge Closure

The State Route 165 Carbon River Fairfax Bridge closed April 14, 2025, after inspections revealed new deterioration of steel supports on the 103-year-old structure.

www.flickr.com

https://www.seattletimes.com/seattle-news/key-bridge-to-mount-rainier-starting-to-buckle-closes-indefinitely/

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Like I said in that linked post, that's not really fair on the NTSB. What they really said was bridges designed to rust like Corten, can still corrode much more than anticipated and regular inspections need to be followed by repairs and maintenance. Inpatricular if water rand sal are allowed to gather in one place and not dry off you can get accelerated corrosion.

The Carbon River is glacier-fed, and the canyon is a mess of loosely agglomerated ash and friable andesite rock from the volcano. People are injured and killed somewhat regularly on the Carbon river, because sunshine on the Carbon glacier in the afternoon causes rapid melting and subsequent flash floods down the steep ravines, which are difficult to rapidly climb out of, especially when the floods are eroding the terrain you are standing on. The steep terrain gives high velocity flows, which carry a lot of heavy debris, you do NOT want to get caught in it.


The bridge has made access easy for unaware and untrained people to a very dangerous place. Not rebuilding the bridge is not a bad idea, and I'm sure park rangers and S&R people are weighing in on the discussion.

https://en.wikipedia.org/wiki/Carbon_River - see especially the section titled "Natural Hazards"

The local hiking guide website entry on the Carbon Glacier Trail (which follows the river) makes interesting reading as well, with description of washouts and regularly replaced log bridges over rapidly eroding stream banks: