# Stone Arched Trail Bridge Design Available



## zachi (Jul 25, 2006)

We just finished this stone arched bridge in Forest City on the Sandusky Trail. FC is 3 miles S of Downieville, Ca. The bridge design utilizes engineering from Europe that cut concrete down to a minimum (6" think). This took 6 weekends of volunteer work to build and is 45 ft long with a buried 20ft arch. Stone was locally quarried. Let me know if you are interested in design information. We have built several SABs, you can see more at https://www.casaditerra.net/bridgenews.htm 









We have been working with the USFS for over 10 years and have 100 miles of new trail approved on our prospectus to build over the next 5 years. If anyone that wants to play, the area is pretty sweet. Our goal is to connect three mountain bike rec areas (Bullards Bar, Forest City and Downieville) with routes that support multi day expeditions. It is our vision to provide trails and the logistical information for people to come and adventure.









Our group ownes two trail excavators, a walk behind dozer, rokon trail bike, mech wheelbarrel, three wheelers and more. If you are tired of sneaking around building trails, consider participating in designing and building killer trails in the High Sierra's. This is a non profit collaboration of artists, designers, dirt rats and wild cards.









Besides miles of undulating and meandering trails (Ummmm...) we are building tech and free riding elements as well like this gem called the pearl necklace.








This tech section has a 5ft high boulder causeway 16" wide that descends a 40% grade to a narrow sweeping turn (most difficult part) back to the trail.

We are currently cutting 2 trails, High Grade and Ridge Runner. We are currently collecting other fellow cyclepaths to join our core design and build group. 
Foresttrailsalliance.org If you are from the N Calif area and want to play....


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## OGJON (Apr 15, 2009)

This tech section has a 5ft high boulder causeway 16" wide that descends a 40% grade to a narrow sweeping turn (most difficult part) back to the trail.

I like this ^^^^^^^^^^^^^^^^^^^^


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## formica (Jul 4, 2004)

Nice work, thanks for sharing.


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## Uncle Six Pack (Aug 29, 2004)

very cool

nice work of art


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## bsieb (Aug 23, 2003)

Nice to see this caliber of work on a bike trail. :thumbsup: The bridge reminds me of Acadia NP in Maine.

I am interested in the design info, do you have much freeze/thaw weather conditions at your location?


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## bighitdon (Oct 28, 2004)

zachi,

i've been wanting to do this type of bridge on a very small scale stream crossing on my local trails for about 10 years. but i have no idea where to start learning how to build it.

if you've got info on it, i'd be appreciative if you could pass it along. makes me wish you were on the east coast.

nice bridge. i think that goes without saying, tho.


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## zachi (Jul 25, 2006)

This bridge was very easy to make. We used a slip form technique. We build a plywood and masonite form that mimics the shape of the underside of the bridge. 








From there we drystack the rock on the form and then spread dry sand in between the rocks. This stops the mortar that we coat the back of the rocks with from bleeding through to the finish. We wet mix the back side of the mortar with concrete and rebar. 








The bridge above has an integrated arch rather than a buried arch. We shaped the side plywood forms to mimic the finish surface of the bridge. Rocks are placed against it and mortar sparged from behind. 
I have the engineering for the 20ft span bridge and willing to share that with anyone who wants to build it. Even that bridge is still WAY overbuilt though. I have done some sweet 16" wide 6" think free ride elements as well. They are fun and turn out beautiful.


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## ~martini~ (Dec 20, 2003)

Wow. Impressive stuff!


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## pspwesty (Feb 27, 2006)

Nice work there!


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## zrm (Oct 11, 2006)

Pretty cool, but that's gotta be expensive.


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## zachi (Jul 25, 2006)

*not expensive*

This is mostly labor. The concrete mix is $12 per ton, a little rebar. Rock cost about the same. So for creative trail projects it works out sweet. The big bridge used lots of everything but still only cost us around $1400. The small bridge was around $250.

Water reducers help the risk of freeze thaw issues by creating a more waterproof and stronger mix.

z


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## Skookum (Jan 17, 2005)

Amazing work!


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## bikerjay (Sep 16, 2007)

SWEET, old world craftsmanship with new flair. Keep up the good work. That stuff looks CCC grade, and that is really the best compliment a trail crew could ever get.


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## k2biker (Jan 13, 2004)

That is awesome! Very nice work on the bridge and kudos to your completed work and prospectus! I have a couple places in mind on for stone bridge work on our project here in Atlanta and I'm glad to see more of 'em.

Thanks for your work!


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## bsieb (Aug 23, 2003)

zachi said:


> This is mostly labor. The concrete mix is $12 per ton, a little rebar. Rock cost about the same. So for creative trail projects it works out sweet. The big bridge used lots of everything but still only cost us around $1400. The small bridge was around $250.
> 
> Water reducers help the risk of freeze thaw issues by creating a more waterproof and stronger mix.
> 
> z


We have daily freeze thaw cycles in the winter, like 50 degree days and 10 degree nights, and flaking and cracking are real problems when moisture is present. Do you think the bridge construction will handle these conditions?


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## NEPMTBA (Apr 7, 2007)

My friend Ian Cramb would be proud of that! We were introduced to Ian by our friend Chuck (11Deacon on MTBR) Ian gave as a gift to our friend Loren his book and even signed it for him. Ian lives in Pennsylvania.

He can teach ya, buy his book he built Eric Clapton's house, yes that EC!

http://www.amazon.com/Art-Stonemason-Ian-Cramb/dp/1558702253http://

http://www.gambino-stonemasonry.com/ian_cramb.html


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## zachi (Jul 25, 2006)

It is located at 4k feet. We used some acrylic water reducer to limit the damage that can be caused by freeze thaw. 
It has wintered its first with no visible signs of distress. 
there are other things you can do like using air entrainers to farther reduce these risks.
z


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## BigWheel28 (Jan 21, 2007)

Zach - dont leave out all the good stuff!

like how all the rocks are local and all the work put into gathering them.

Yeah it didn't cost much - but truly a freakin' amazing amount of detail went into the work.

Can't wait to ride it.


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