Forum Index > Trip Reports > Eureka Creek Footlog Bridge Completion, October - November, 2022
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KarlK
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PostWed Nov 09, 2022 1:29 pm 
The Monument Creek trail # 484 begins from the Harts Pass road about seven miles NW of Mazama, courses NE alongside the Lost River, and in about four gently undulating miles reaches Eureka Creek near its confluence with the Lost River at ~2600’elevation. For seekers of a genuine wilderness experience, the realm N of Eureka Creek will "give it to you good and hard" (hat tip to H.L. Mencken). For climbers ticking off Washingon's 100 highest peaks, three (Lake Mountain, Monument Peak and Blackcap Mountain) are situated between the terminus of Eureka Creek and the creek's headwaters near Shellrock Pass; the main challenge, though, is just getting to the part where you start climbing. For hikers, seekers of mythical forest denizens, backcountry fisherman, or for lunacy-adjacent backpack hunters, the trail along Monument Creek NE of Pistol Pass affords a banquet of wilderness and wildlife splendor rich with creatures large and small. This is a place where wild things abound and fortune favors audacity and preparation. Therefore, the long-abandoned section of trail between the Eureka Creek crossing and Shellrock Pass represents a worthy target for reopening. This constitutes a major challenge of the sort that attracts hardy non standard-issue gals and guys afflicted with a penchant for heavy load carrying, extensive crosscut saw work and abundant experience with the phenomenon of "beware what you wish for." Eureka Creek typically runs too swift and deep until late July or August for safe wading, posing for many years a chilly and potentially lethal ford for earlier season hikers. This problem stemmed from flooding on or about May 15, 2008, which washed out the stock bridge (https://www.nwhikers.net/forums/viewtopic.php?t=7967052&highlight=eureka+ck+bridge).
Copy of original stock bridge from the link above -- the truss increased susceptibility to washout
Copy of original stock bridge from the link above -- the truss increased susceptibility to washout
Notably, the popular hike to Eureka Creek (and a favorite of local trail runners) is in splendid shape owing in large part to an immense amount of trail work organized largely in recent years by a monumentally determined guy I refer to as The Other Mike. I'm happy to note also that WTA lists this trail as part of their Lost Trails campaign, but so far as I can tell, WTA has not formally sponsored work parties on it since 2012 (see https://www.wta.org/go-hiking/hikes/monument-creek). While Mike is a member of WTA, as are several other crew members associated with this trail and bridge project, it should be emphasized that the work described here owes hugely to The Other Mike, his cadre of non standard-issue trail-fixer friends, and also to the vital support of Dianne and Joe Hofbeck and their Pasayten Wilderness Trust as explained below. Going forward, WTA hotshot crew involvement would be a terrific asset to this project. Mike's goal -- and he literally has a 10 year plan to accomplish it -- is to reopen the abandoned and severely in-need-of-work 20 or so miles of a premier 44 mile loop hike encompassing Pistol Pass, Shellrock Pass and the headwaters of Eureka Creek; the loop is completed via the Middle Fork of the Pasayten River and Robinson Pass trail (for loop hike details see p. 372 in Erik Molvar's largely obsolete Hiking the North Cascades) (this book, readily available at REI, is now something of a historical record of the loss of maintained trails in the Pasayten and elsewhere). Well, the footlog bridge part of the project is now a done deal. It's a beauty, designed by retired structural engineer Joe Hofbeck, blessed by Magic Trail Elves, and made possible by the Dianne and Joe Hofbeck Trust (see below).
All rights reserved (Joe Hofbeck photo); L to R: Nate, Baily, Conner, Allen, Steve, Dave, Dianne and Joe Hofbeck, a modest sampling of all the people who have contributed to this project
All rights reserved (Joe Hofbeck photo); L to R: Nate, Baily, Conner, Allen, Steve, Dave, Dianne and Joe Hofbeck, a modest sampling of all the people who have contributed to this project
Joe H working on the bridge -- bottom of bridge is ~2-3 ft higher than former truss bridge, making it resistant to washout.
Joe H working on the bridge -- bottom of bridge is ~2-3 ft higher than former truss bridge, making it resistant to washout.
Magic Trail Elf Door
Magic Trail Elf Door
A key part of the doing took place Oct 6-14, 2021 when the donor tree was felled by Landon Decker, the Methow Ranger District's very capable trails manager, with the assistance of his crew, and then subsequently peeled with the additional help of a merry band of volunteers (https://www.nwhikers.net/forums/viewtopic.php?t=8034937).
Felling the donor log, Oct 12, 2021
Felling the donor log, Oct 12, 2021
Another essential part happened in early May, 2022, when The Other Mike milled a Douglas fir log into the planking and rail material for the bridge; the log came from Mike's property and the milling was done via chainsaw, bandsaw and planer. An enormous amount of work went into this process, and the dollar value of the milled wood would equate to sticker shock severe enough to probably require an infusion of several units of saline. Mike also donated all of the fasteners. And wore out a 32" chainsaw bar. Hey, no good deed goes unpunished, right?
Yeah, looks hopelessly manky but just you wait
Yeah, looks hopelessly manky but just you wait
Milling boards for bridge lumber - note layout on log end
Milling boards for bridge lumber - note layout on log end
Milling progress - tough on chainsaw bars!
Milling progress - tough on chainsaw bars!
Bandsaw phase
Bandsaw phase
Planing phase
Planing phase
And then came the matter of carrying hundreds of pounds of lumber the four miles to the bridge site, a task initially distributed among several volunteers in May with The Other Mike taking on a disproportionate share of that job as well.
KarlK, AKA Not-a-Horse, packing boards in May.
KarlK, AKA Not-a-Horse, packing boards in May.
Another vital key to this project was the funding for the bridge itself -- $10,000 worth -- provided by the Dianne and Joe Hofbeck Pasayten Wilderness Trails Trust (https://pasaytentrailstrust.org/index.html). The Trust gave the Ten Grand to the Forest Service in the form of a "gift with conditions" to ensure their committment to the bridge project per se (new outhouses are not helpful for getting across rivers). Completion of the bridge took place Sunday September 11th through the 18th. Horsepower provided by the FS packed a metric F-Ton of handtools to the worksite, which, being within official Wilderness, is off limits to power tool use in FS-administered wilderness in accordance with the 1964 Wilderness Act. The remaining lumber was also packed in on horseback.
Horse packing boards
Horse packing boards
All rights reserved (Joe Hofbeck photo); retired Seattle Firefighter and dauntless Trail Fixer DonH
All rights reserved (Joe Hofbeck photo); retired Seattle Firefighter and dauntless Trail Fixer DonH
All rights reserved (Joe Hofbeck photo); Bailey, DaveS and DonH
All rights reserved (Joe Hofbeck photo); Bailey, DaveS and DonH
All rights reserved (Joe Hofbeck photo); SteveG
All rights reserved (Joe Hofbeck photo); SteveG
All rights reserved (Joe Hofbeck photo); Rachel and AllenJ
All rights reserved (Joe Hofbeck photo); Rachel and AllenJ
All rights reserved (Joe Hofbeck photo); DonH and SteveG hand drilling holes
All rights reserved (Joe Hofbeck photo); DonH and SteveG hand drilling holes
All rights reserved (Joe Hofbeck photo); Bailey and LandonD log wrangling
All rights reserved (Joe Hofbeck photo); Bailey and LandonD log wrangling
All rights reserved (Joe Hofbeck photo); Lots of woodworking
All rights reserved (Joe Hofbeck photo); Lots of woodworking
Yarding footlog into place
Yarding footlog into place
One final tweak occurred when JoeH, DonH, and KarlK hiked back in and replaced the post shims with better shims on November 1.
ABS shim installation, Nov 1, 2022
ABS shim installation, Nov 1, 2022
Regarding the steep long-abandoned trail N of the new bridge, Mike and a two other volunteers spent four days working on it in late September, and made it to 5400'. They each carried three gallons of water to their high camp and were hampered by thick smoke from this summer's Pasayten fires. Mike reports that there is a particularly bad section between 4800' and 5100' where the original trail is gone, baby, gone. Users have been going straight up the hill, and it's steep. The trail is reportedly in relatively good shape beyond Mike's high point. The next step is to figure out how to get more help with this project. I did mention that this trail is part of WTA's Lost Trails Initiative, and I'm optimistic that the MV Ranger District and MV Trails Collaborative will remain supportive.

Karl J Kaiyala

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Kim Brown
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PostWed Nov 09, 2022 1:59 pm 
This is a great project, wonderful photo essay to know how it's done, and what hard work it is. And the Hofbeck Fund is cool.

"..living on the east side of the Sierra world be ideal - except for harsher winters and the chance of apocalyptic fires burning the whole area." Bosterson, NWHiker's marketing expert
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RichP
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PostWed Nov 09, 2022 2:05 pm 
A thousand thanks to you all.

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brewermd
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PostWed Nov 09, 2022 2:19 pm 
Thank you all for all of the hard work!

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Stefan
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PostWed Nov 09, 2022 3:57 pm 
Wow. that is awesome!

Art is an adventure.
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Bowregard
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PostWed Nov 09, 2022 4:52 pm 
Thanks for all the hard work and dedication. Just curious - Does anybody happen to know anything about the design load criteria for a footbridge like this? I see 9 people standing on it and I am sure it is super stout but I just got to wondering what loading conditions they might design for. I would think snow loading would be fairly straightforward but it is essentially a one lane bridge. Do they assume multiple people would get on at the same time and do they introduce a factor to account for degradation of the wood over a specific period of time? It just strikes me as somewhere between a group of hikers pushing a log over a creek for passage and a city footbridge project and makes me wonder.

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fourteen410
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PostWed Nov 09, 2022 6:04 pm 
Thank you! I'm curious - how do you determine what makes a good donor tree for a log bridge, other than length/height?

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KarlK
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PostWed Nov 09, 2022 6:19 pm 
That's a teriffic question Bowregard. The Forest Service does publish design criteria for backcountry bridges that basically ensures that bridges are overbuilt, and Joe Hofbeck spent considerable time making sure that the footlog bridge design and execution complied with those criteria. Joe's a first class structural engineer who takes this stuff very seriously. The FS had one of their engineers vet the design, and Landon (the MVRD trails manager -- very solid guy) felled a Doug fir that nicely met the specs. Doug fir is terrific construction wood. You'll also note that the log is arched upward a bit, which adds considerable strength. I'll check with Joe for more details.

Karl J Kaiyala

Bowregard
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Bowregard
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PostWed Nov 09, 2022 8:20 pm 
KarlK - Thanks so much for the prompt reply. I will have to look for the published design criteria. My education was ME so I am not familiar with bridge design issues but of course the physics is the same. I noticed the fir tree which is stronger than Cedar albeit with less bug/rot protection. It is great to see the cooperation with the FS, trails, and work crews. I was a bit shocked at seeing the guys with a handsaw to take down that tree but I bet that was fun in a way too. I find your comment about the slight arch adding considerable strength to be interesting. I was taught that a slight rise in beam bridges had very little effect on strength (and can be ignored for the purpose of analysis) though it is wise to build with a rise to reduce the visible effect of any deflection.

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iron
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PostWed Nov 09, 2022 8:56 pm 
Bowregard wrote:
KarlK - Thanks so much for the prompt reply. I will have to look for the published design criteria. My education was ME so I am not familiar with bridge design issues but of course the physics is the same. I noticed the fir tree which is stronger than Cedar albeit with less bug/rot protection. It is great to see the cooperation with the FS, trails, and work crews. I was a bit shocked at seeing the guys with a handsaw to take down that tree but I bet that was fun in a way too. I find your comment about the slight arch adding considerable strength to be interesting. I was taught that a slight rise in beam bridges had very little effect on strength (and can be ignored for the purpose of analysis) though it is wise to build with a rise to reduce the visible effect of any deflection.
(structural engineer here): i just did a super crude calc making some assumptions.
assume the tree is 24" diameter, and spans 40ft. taking a very conservative 100psf live load (hard to do, see image below), the factor of safety is 1.6. this also assumes a crappy wood of 900psi, but you're likely more in the 1500psi territory which would increase FOS to 2.6. further, if you assume 60psf live load, with 1500psi wood, then you're at FOS = 3.5
camber of a beam has no impact to strength. it's just visual appearance for user comfort. if you had a true arch, with buttresses supporting the ends (think roman aqueduct), then you turn your arch into a compression-only member, which is essentially a column, not a beam. that's not what's going on here. any arch of a natural tree has zero impact on strength. (note: i barely do calcs anymore, am on about 3 hours of sleep, and speak in metric now, so take this all with a grain of salt)

wallorcrawl, Brushbuffalo, Bowregard
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Kim Brown
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PostWed Nov 09, 2022 9:21 pm 
Seems an arch allows some give for snowload. Granted, it's a narrowish log, but heavy snow is heavy snow. But I studied literature, so there's that..... embarassedlaugh.gif

"..living on the east side of the Sierra world be ideal - except for harsher winters and the chance of apocalyptic fires burning the whole area." Bosterson, NWHiker's marketing expert
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Bowregard
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PostWed Nov 09, 2022 9:34 pm 
Thanks Iron, That answers a bunch of my questions (and good to know my memory is not as foggy as I feared). Sounds like you guys load it the same way we used to load an airfoil surface - psi/psf. I guess that makes sense although I agree it would be hard to imagine 55 people on that bridge ( (200plf x 40ft)/145lb = 55 people ). Your comments regarding slight camber vs true arch (and camber being for visual appearance) are consistent with what I remember from school. I pretty much stopped doing calcs for work 25 years ago. Funny how it was a royal PITA back then but I kind of enjoy when I have a reason to do it now. Anyway - thanks for the info

Brushbuffalo
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PostThu Nov 10, 2022 12:54 am 
Bowregard wrote:
KarlK - Thanks so much for the prompt reply. I will have to look for the published design criteria. My education was ME so I am not familiar with bridge design issues but of course the physics is the same. I noticed the fir tree which is stronger than Cedar albeit with less bug/rot protection. It is great to see the cooperation with the FS, trails, and work crews. I was a bit shocked at seeing the guys with a handsaw to take down that tree but I bet that was fun in a way too. I find your comment about the slight arch adding considerable strength to be interesting. I was taught that a slight rise in beam bridges had very little effect on strength (and can be ignored for the purpose of analysis) though it is wise to build with a rise to reduce the visible effect of any deflection.
I knew someone who was construction superintendent for the monorail. He talked of the designers’ concern with deflection being noticeable by riders. Of course the load on the span changes rapidly. There was some arch added just for purpose you describe. Concern was that passengers would notice difference at piers. I want to say there was some addition at piers, shims(?), after trials. On reflection I think there was material added, with taper out from piers. This may have been intentionally thickened at pour, and ground down after trial with a taper. This would have been as a boy sitting between two men driving up the Cariboo in 1971. Place your own +/- on accuracy of memory. Hope not total diversion. Should have built some arch in topic. PS. At time I thought monorail construction was a long time ago. I was surprised these old guys still remembered details. Of course I’m well older than they were then and I remember something of it fifty years later.

Keep Calm and Carry On? Heck No. Stay Excited and Get Outside!
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Sculpin
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PostThu Nov 10, 2022 8:24 am 
iron wrote:
camber of a beam has no impact to strength. it's just visual appearance for user comfort. if you had a true arch, with buttresses supporting the ends (think roman aqueduct), then you turn your arch into a compression-only member, which is essentially a column, not a beam. that's not what's going on here. any arch of a natural tree has zero impact on strength.
Mechanical engineer here. KarlK was right about the slight arch giving added strength, where the word "strength" refers to a reduction in the magnitude of downward deflection when the beam is loaded in the middle. The arch in the tree adds nothing to the tensile strength of the log, if that was what was meant. But it most certainly aids in carrying live load. If an array of load and deflection sensors were placed across the span, it would be obvious how the compressive load vectors pass though more wood in an arched structure than a straight log, effectively increasing the thickness of the log with respect to deflection under bending. (Wish I had the IT savvy to diagram this.) In a straight beam, the bending load caused by a weight in the middle resolves to a tensile component on the bottom in the middle, as well as at both ends. This is accompanied by a compressive load on the top in the middle. When you put an arch into the beam, the vector path of the compressive load passes through more wood, putting more of the live load into compressing the beam rather than stretching it. This will always cause a decrease in downward deflection and increase the magnitude of the load required for failure of the beam. That means it is "stronger." It is not intuitive, but that is how it works. FWIW, Wikipedia agrees. "A camber beam is much stronger than another of the same size, since being laid with the hollow side downwards, as they usually are, they form a kind of supporting arch."

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KarlK
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PostThu Nov 10, 2022 8:26 am 
Hey Bowregard and FourteenFourTen -- Numero Uno -- you are correct about the camber not contributing strength (Joe deducted points from my grade owing to this). The physics are kinda interesting and working through them is helping to shake loose some rust off my brain. Numero Two-oh -- here's a link to FS bridge standards: https://www.fs.usda.gov/recreation/programs/trail-management/documents/plans/trail_bridge_pdfs/COMBINED_STD_TRAIL_BRIDGE_PLANS.pdf

Karl J Kaiyala
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