I have the best job in the world.  Sometimes I get to work with a dedicated citizen and a group of willing volunteers to make something lasting and beautiful.  (And useful!)  Come and see this bridge in Petersburg, Alaska!

I acquired a grant to put in a bridge over a stream that was between a park and a mile long trail.  The plan had been to install a glue-lam or log bridge across a 50 foot wide part of the stream.  Building a log bridge is actually pretty easy if you have big timber to work with.  But a citizen approached me and asked if he could design and guide the construction of a cantilever bridge with a small hut on it.  Shortly afterward a Boy Scout was looking for an Eagle Scout project... and here is the process.

Step 1: Design

Working with local Forest Service engineers the designer took his vision for the project and ensured it was matched up with the right diameter and species of log.  The engineer did calculations and accounted for humans and heavy snow weight to ensure that the volume of concrete and fill used for the cantilever would be adequate.

We were able to use a significant rock to perch the hut on and as the fulcrum point for the long cantilever.  However, after calculations regarding the volume of water and high tide we had to raise and enlarge this point.

Designer's statement:
This bridge consists of two cantilevered wings meeting but not touching, in midstream.  The concept is of a glorified log crossing.  This bridge is not handicap accessible; in fact it is intended to bounce a bit, just like a log, before one crosses to the other side.  The moss covered Troll Booth along the way can seat four people.
My vision is to encourage the pedestrian to pay attention and to enjoy a playful transition from one side of the creek to another.  the cozy Troll Booth will make one want to pause, listen and watch.  The view of the narrowing walkway ahead, and of the wings not touching, and the slight bounce of the bridge will alert ones' senses.  As one steps onto the other wing, the crux is passed.  Making the turn and reaching the stability of the other bank will complete the transition across the gateway.
Some people may not want to cross the bridge, because it requires paying attention, just like the trail ahead.  And that's ok.  There is a little here for everyone; it's more than just a bridge.  Going part way and just sitting in the Troll Booth offers its' own rewards.  As in life, it's a rough trail ahead, and we must pay attention as we cross each bridge along the way.

Step 2: Center Foundation

The hut will be located above the large rock in the stream.  But we wanted to make the rock really suit our design.  A form was built around the rock and upstream.  Bolts were positioned for straps to attach to the logs.  Rebar was tied throughout and a few holes were drilled into the rock with a carbide masonry bit and a Hilty hammer drill.

A ramp was made with 4x4 posts and 2 foot wide strips of plywood.  We then packed the concrete into the site with wheelbarrows.  Prodding into the concrete often and tapping the form sides to get a good pour.

Then we removed the form after ample time to cure.

Step 3: Foundation Slabs

Forms were made to pour slabs that could be carried to the site.  These slabs ensured that the bridge abutment was on solid ground, had adequate rise, and gave space for gravel fill.  A specific bolt pattern was devised to connect the slabs using flat stock steel.  The steel pieces were created after the slabs were dry and in place allowing for a little bit of variance.

Bolts were set in the forms along with rebar and all of it tied together with wire.  Forms were tapped with a hammer and prodded well with spare rebar to ensure minimal air pockets.

Step 4: Assemble the Foundation

Using a small excavator we cut down to the specified depth and installed the foundation pieces on each side of the stream.

Moving large slabs of concrete is easier with the right equipment!  Keeping things level at the beginning makes things much easier in the end.  Look at all of the photos and you'll see that the log pair that is supported in the center has only three slabs composing the foundation.  The unsupported cantilever has a much more complex design.  One cross piece forms a toe of the abutment.  On top of that, the two side plates sit.  And on top of them are the two points for the logs to attach to as well as a plate to help make sure adequate fill supports the cantilever.  All but the rear plate are strapped and bolted together with steel stock.

Step 5: Bring the Logs

At one point our plan was to use galvanized steel I beams.  Then we considered telephone poles.  Finally we settled on locally harvested yellow cedar.  We picked them out of a sort yard and had them delivered.

Originally we planned to carry the logs to the site with lots of people.  Then we planned to roll them in on plywood and pipes.  Finally we decided that an all-terrain forklift would be best.  The extendable boom, side to side tilt, and heavy load capability made it much safer and easier to install.  Rent was just about \$100 an hour for the unit and each log was placed within a few inches of where it needed to be.

At the spot where the logs would meet (but not connect) we assembled a stout crib of lumber.  The logs would need to rest on this until they were bolted down and the back fill placed.

The smaller logs for the shorter (but not supported in the center) cantilever were brought close with the forklift and then placed by volunteers.  Then all logs were marked for notches, rolled over, and cut with a chainsaw.

Step 6: Notch for the Straps

Notches were cut with a chainsaw and chisels to connect the foundation to the logs.  Steel angle iron was used to bolt the logs to the foundation.

Aluminum flashing was used to protect the top side of the logs from weathering.

Step 7: Decking

Treated decking was selected and specifically spaced wider than on a home deck.  The intent was that pine cones and other debris would fall through easier.

Deck boards were placed abutting each other and longer where the hut was placed so a dropped lip balm wouldn't end up in the stream.

Angle cuts the length of the deck boards were made at the ends of the cantilevers so that each board had solid contact with the logs.

Each board was installed with two lag bolts and washers.  The deck was countersunk and then impact drills were used to drive the lags.

Afterward all edging was routed with a rounded bit to smooth edges.

Step 8: Fill

Using manpower and wheelbarrows gravel was packed to the site and fill was dumped and compacted.  Sills were made with leftover deck boards to help keep the gravel where it needed to be and to make steps to get up and down at the bridge abutments.

Step 9: Install Hut

This design incorporates a "sod" roof of locally harvested mosses as well as integrated benches. The entire structure except the plywood on the roof is constructed of red cedar. Most of the pieces were fabricated in a wood shop and then carried out and installed.

A waterproof membrane was attached to plywood and then old fishing net was draped over the roof to provide the moss with a stable foundation.

The bridge has considerable spring to it - it has a few inches of travel just walking on it normally. Bouncing on it will flex it (the section that isn't supported in the center) about 8 or 9 inches.

Total project cost: just over \$10,000 not including donations and a few hundred hours of volunteer labor.

<p>Wow, that is really amazing!</p><p>Congratulations on your success and many to come!</p>
<p>Thanks for sharing, this is well done.</p>
Why cantilevered?&nbsp; Why not two piers?&nbsp; Other than asthetics of course...
That's what is special about artistic work such as this! You work with what is naturally available, i.e. a rock at mid stream!<br><br>Cantilevers are very interesting, i.e. Husky stadium at the UW in Seattle. It was designed as a cantilever system. To the average person on the street it appears as impossible.
Purely aesthetics.&nbsp; The designer definitely had a vision of making the bridge much more than a way to cross the stream.&nbsp; He wanted the bridge to be an attraction, and something to engage the senses.&nbsp; <br />
I live in Alaska and if I find my self down that way I want to go and see this!
the hut on the bridge in simply exquisite : great place for meditation I would say
I would just love copy of those plans.
As a resident of Anchorage Alaska I am apalled that you didn't have the consideration to put this bridge near me so I can go see it.&nbsp; : )&nbsp; Good job.&nbsp; Maybe I will have to take a trip to Juneau one of these days a swing by Petersburg to see the bridge.
This bridge is a work of art, give my compliments to the designer and the Boy Scout (now an Eagle Scout I&nbsp;guess)<br />
<p>Looks Great Zieak... may i ask<br /> the Bridge designers name? Might as well give him some online credit... ;0)<br /> Did you have&nbsp;a part in the design as well?<br /> How long from start to finish?</p> <p>Where exactly is this bridge?</p> <p>After thought - Can one see it on google satilite&nbsp;maps i wonder?<br /> <br /> Best time of year to hike the trail to see your Bridge project or should one say &quot;Our&quot; new bridge... ;0)<br /> <br /> Again hats off to you and all involved.</p>
I&nbsp;didn't know if he wanted his name posted online - but when I last spoke to him I mentioned this Instructable and he didn't seem to be phased... Dieter Klose.<br /> <br /> I&nbsp;met with him a few times during the process but only in a supportive role. &nbsp;<br /> <br /> The bridge is located <a href="http://maps.google.com/maps?f=q&amp;source=s_q&amp;hl=en&amp;geocode=&amp;q=99833&amp;sll=38.915577,-77.027042&amp;sspn=0.073995,0.179043&amp;ie=UTF8&amp;hq=&amp;hnear=Petersburg,+Wrangell-Petersburg,+Alaska+99833&amp;ll=56.803792,-132.912169&amp;spn=0.026034,0.089521&amp;t=h&amp;z=14" rel="nofollow">here</a>.&nbsp; But online satellite maps are not good enough resolution for my area to see the bridge or to zoom in close enough to even see the stream. &nbsp; <br /> <br /> The bridge is only 200 feet from the parking area inside Sandy Beach Park so any time of the year is good!<br />
Arkansas might be a great state with good parks and scenery... But Alaska has even better!&nbsp; <br /> <br /> Just kidding - people make that mistake with AK all the time.<br /> <br /> It is located in Sandy Beach Park.&nbsp; My father is a photographer and took <a href="http://www.finalimpressions.com/printindex/Trail%20to%20City%20Creek.htm" rel="nofollow">this one</a> of an old cabin chimney that's about 150 feet further along the trail.&nbsp;&nbsp; <br /> <br /> The path is one mile long.&nbsp; It isn't developed at all though - just a swath cut through the forest along the beach.&nbsp; But A \$26,000 grant will upgrade that path this coming summer.<br /> <br /> Dieter hasn't done any other bridges like this.&nbsp; His work primarily involves residential and commercial buildings.&nbsp; If you look up his name online you can read about his mountaineering experiences in the are though!<br />
Thanks Chase.&nbsp; If you ever make it up to Alaska I'd be happy to give you some good tips on places to visit!<br />
I'll&nbsp;just may take you up on that &nbsp;- fav'd your instrucable to save it.<br /> <br /> Take care and stay warm!<br /> -chase-
Really, really nice job.&nbsp; I just took a virtual tour of Petersburg and It, and your bridge, are on my bucket list.&nbsp; Suggestion....Could you place a photo or two of your bridge on Google Earth to show it's location.<br /> Congratulations on such a great project.&nbsp; I'm jealous.<br /> -Mike<br />
You put in a lot of work. Too bad some citizens can not enjoy it. Don't forget to consider the ADA when designing projects such as this
It was a guarded choice to not make it entirely accessible.&nbsp; The rest of the trail will not be built to ADA guidelines.&nbsp; And it is worth noting that trails are exempt from those legal restrictions.&nbsp; Are you familiar with the work of Beneficial Designs? Their system of mapping trail characteristics to determine the level of accessibility is a much better measure of the degree of ability necessary to enjoy remote trails.<br /> <br /> Before this bridge, a person with any mobility impairment, loss of sight, or any other of many limitations would find this route (it is 200 feet from a parking lot) completely inaccessible. &nbsp; <br /> <br /> My first job in my degree focus after college was providing recreational services for people with disabilities.&nbsp; We took them out cross country and downhill skiing.&nbsp; Ever loaded someone with severe MS into a chairlift?&nbsp; I'm just saying to let you know I'm very well aware of the struggles of people with disabilities.&nbsp; But I'm just as well aware that if there is a will, there is a way.&nbsp; And that this is not a topic I take lightly.<br />
this is great! How did you acquire the grant? Was it a local grant?<br />
Actually it was a federal grant through the Forest Service.<br />
So awesome.<br /> Does anybody have a picture of the view from the hut, down (or up) the stream?
I need to work out there and will take a few pictures with my cameraphone.<br />
This is fantastic &amp; a credit to yourself &amp; all involved. Very, very well done.
I appreciate that!<br />
&nbsp;&quot;Troll Booth&quot;...I love it! &nbsp;<br /> <br /> GREAT bridge, wonderfully executed!<br />
Thanks!<br />
It look very well done. I&nbsp;see your group took the time to plan the whole thing out and it definitely paid off. Good work and good luck on your next project!<br />
did you guys dam up the stream while you worked?
Nope.&nbsp; The variation in the flow just really depended on the amount of rain we had.<br />
I'm blown away.<br />
This is really great.&nbsp; And, yes, you do have one of the best jobs in the world.<br />
hey I was just looking around on instructables and came across what looks a lot like Sandy Beach in Petersburg, (were I grew up) really cool
That's the place!<br />
When was the project completed? I spent a summer in Petersburg a few years ago. Would love to see the bridge, so maybe this gives me an excuse to get back there at some point. Great job!<br />
&nbsp;This is beautiful for several reasons;<br /> <br /> 1. It get's you across the creek.<br /> 2. It provides a place to stop, listen, reflect, and enjoy nature.<br /> 3. It's made mostly from nature and would eventually return to nature.<br /> 4. It's whimsical in it's design and construction.<br /> 5. It's made by people who care and want to spread that to others.<br /> <br /> Thank you! &nbsp;This is a gift to everyone. &nbsp;You brought me joy today.<br /> <br /> John<br />
What is it with you Alaskans and these &quot;bridges to nowhere&quot;!?
maybe some outdoor lamps shining to the river would be cool, this might make it easier to fish.........well if theres fish<br />
Hello.<br /> I just wanted to ask is that stream a host to spawning salmon?<br /> <br />
In 10 years i have never seen salmon in that stream.&nbsp; It would make for a great observation platform.&nbsp; There is a smaller stream close by that i have seen fish in and some harbor seals prowl the bay there though.<br />
That must be the dodgiest bridge I've ever seen, but I love it!
&nbsp;Nice work! &nbsp;It is nice to see people improving their areas and parks, it shows care for an otherwise dying recreation (or, at least it is in my area). &nbsp;I'll see if I can do anything in my local park!
Gives new meaning to my designer's statement: &quot;<em>Some people may not want to cross the bridge, because it requires paying attention...&quot;</em>
It really is an awesome bridge. I never thought people would get so excited over a footbridge, but everyone really likes it because it is so unique. Our family has traversed it many times. This is a early snowy morning in December.<br />
Nice picture Tye!<br />
This is awesome. <br /> <br /> Is this part of a park? It looks like a gorgeous area.<br />
It is part of Sandy Beach Park.&nbsp; It is a small &quot;city&quot;-owned park in a tiny island community in southeastern Alaska.&nbsp; And you're right - it sure is gorgeous here!<br />
Really, really, really, very, quite, very awesome.

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Bio: I like making things out of items that would have otherwise been discarded. Check out my other projects!
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