Building 55' Bridge Across Creek - Utility Poles

[gable74]

Spent the better part of a year reading various posts on the net and looking at some actual bridges at parks here in the area before I got going. Quite a bit of good info came from this site so I figured I would post up my progress. Here is a short explanation of of what I have so far with some pics.

Bridge was required because our 36 acres was divided by this creek and we wanted easy accessibility to the other side.
Bridge needed to support people/ATVs only. No vehicles.
Bottom of poles will be about 42" above average water surface. Been here for 30 years and water has never risen more than a foot even during flood stage.
Went with (6) 14" x 30' utility poles.
Bridge deck will be 84" wide with the outer poles 50" apart. Third pole centered between the two.
Ripped a flat edge on one side of the poles for the deck boards as the poles were a little bumpy.
Hand dug (6) 16" x 48" footers that are spanned with doubled up 6" x 6" x 8' supports.
Three supports roughly 24' apart.
Had a local lumber mill cut 2" x 8" x 84" white oak planks for the deck. Not nominal, but real 2" thick boards.
Plan on using some unistrut at the mid point (12') of both spans to "tie" all three poles together. Essentially like a clamp.

The bridge is down a long winding trail that is 48" wide at most and the better part of 1/4 mile from the garage, making getting material there a real challenge. The utility poles weighed at least 1200lbs because the E20 excavator was screaming to lift them. Not to mention humping the 80lb bags of sackrete back there, only about 70 bags though....

Due to terrain the poles had to be dragged the last 50 yards down the hill and manually placed on the supports. This was quite the task but we did not want to sacrifice the characteristics of the trail by opening it up wide enough for the excavator, not to mention the logistics of trying to navigate a 1200lb, 30' pole through winding trails. Trees kept getting in the way .

My wife is a park ranger here in the area so I was lucky enough to be able to consult some trail folks who work for the park system before getting under way. I got their stamp of approval.

I plan on getting the deck boards started this weekend, or whenever the outside temps drop to a level I can work outside without having a heart attack.

Anyway, here is what we have so far:

 

[gable74]

Here are the poles in place and a deck board or two after I spent a while getting everything level/plumb. I will be cutting off the cantilevered ends of the poles on the far side where I will start my ramp. The other end will dead end into the earth for a smooth transition.

 

[Rustyiron]

Cool project

 

[Gordon Gould]

Nice to see the use of all that manual labor in order to maintain the present aesthetic environment. Good work !!

gg

 

[MossRoad]

That is impressive! Nice job.

 

[deezler]

Bad a$$. Well engineered, sir.

One immediate question: That creek looks pretty small. Did you consider a trail re-alignment that might have allowed you to have a much, much shorter overall bridge length? Looks like you go over a pond for the first half that you could have possible just gone around.

I wanted rough sawn white oak for my own bridge decking also, but local sawyers kept ignoring my inquiries, and then I came into some free decking anyway. What did those 84" boards run ya?

 

[RjCorazza]

Very nice work! Years ago when building my shorter (10') bridge I couldn't find poles to save my life.

 

[gable74]

I appreciate the kind words all, thank you.

 

[gable74]

One immediate question: That creek looks pretty small. Did you consider a trail re-alignment that might have allowed you to have a much, much shorter overall bridge length? Looks like you go over a pond for the first half that you could have possible just gone around.

I wanted rough sawn white oak for my own bridge decking also, but local sawyers kept ignoring my inquiries, and then I came into some free decking anyway. What did those 84" boards run ya?

When the creek "floods" it widens but doesn't really rise, so I had to be particular about where and how I crossed the area. The first span crosses more of a vernal pool during dry weather and changes to a pond during the wet season. If you looked at the area on a Topo you would get a better understanding, but the elevation on either side of the creek rises about 50' in a very short span. It is the equivalent of about a 10/12 roof pitch. I still came in and "cleaned up" the existing trail to the creek creating a bench cut to level things out, but I really did not want to open things up any more than that. As long as I can get my cart through comfortably, that is all we wanted.

We live on the east coast and within a couple hours of the shore, such we have plenty of vendors who cater to boats, piers, etc., which made finding utility poles and pilings simple enough. I purchased (6) brand new poles for a little over $1500. I had options for used poles, but not knowing what stresses they had been through already, I bit the bullet on new ones.

The white oak planks look fantastic and luckily we have plenty of small mills in the area who love this kind of work. I paid a little over $12 per board and I will need about 105 boards to complete the deck and ramp. If I had to change one thing, it would be the width of the boards from 8" to maybe 10" or 12". It would have cut down the amount of boards, but would have been tougher to get back there because of the weight. Hoping they do not shrink up too much.

The hardest part was getting the poles that last 50 yards down the hill, taking 8 guys to just drag them, luckily since we had to go down the hill, gravity was on our side.
The second hardest part was ripping a straight edge along the grain of (6) dense poles....lol.

Tough to tell from the pics, but having this large bridge nestled in the middle of the woods with only small trails to and from, gives it a very cool feel.

If anyone has any suggestions or questions, just let me know!

I will post up more pics as the project continues.

 

[thclimer]

Keep the pictures coming, this is an interesting project to follow!

 

[PILOON]

You were lucky getting those poles.
Around here that's a big no/no due to creosote usage.
Back in the days we could get all we wanted but no more.

Oh, and nice work, that should last a lifetime.

 

[grsthegreat]

if that was one of my projects, everytime we drop a log off, i would have lost 1-2 helpers before the last log. in a few trips i would be the only person left. not joking. my friends are all lazy sacks.

great looking project though.

 

[workinonit]

Those appear to be salt treated poles, not creosote. I don't think they even make creosote anymore. I know you can't get them around here. They have been outlawed for years.

I'm curious how you ripped the poles? What did you use?

 

[gable74]

Correct, poles are not creosote. Would not have wanted to handle those or have them back there in contact with the wetland.

I used a chainsaw sled and more than a few ripping blades to get one side flat. Something like this:

Amazon.com : Timber Tuff TMW-56 Lumber Cutting Guide : Garden & Outdoor

Amazon.com : Timber Tuff TMW-56 Lumber Cutting Guide : Garden & Outdoor

www.amazon.com

First one I used a couple pieces of wood 2"x6" as the guide, as you can see in the 4th pick of the first post. For the rest, I borrowed a piece of 2"x6" x 30' of aluminum req. tube from work. They both worked well, just the aluminum was one piece and easier to set up. Level out a piece of wood on each end of the pole, then lay your guide on top and screw it down. About 30min later and a chain or two, you got a nice straight edge. Its not a fast process, but it works well if you keep a sharp blade and take your time.

As far as labor, those guys were tough as nails and best part they did it as a favor. I supplied a case of water, 3 bunches of bananas, and 2 boxes of granola bars. They had the first one done in 10 min, by the time they got to the sixth one, things were going much slower .
It has taken me 4 months to get to this point, but hopefully now that the big stuff is done, progress will be a little faster. Still trying to decide on the rail system. My first gut was to go with low bumper rails, something unobtrusive. Maybe 18" or so off the deck that could double as benches. Not sure yet though.

 

[EddieWalker]

Whenever I see a bridge being built, I sort of want to pick it apart. I can't find anything that you have done that could be done better for you use and location. Well done sir!!!!

 

[gable74]

Whenever I see a bridge being built, I sort of want to pick it apart. I can't find anything that you have done that could be done better for you use and location. Well done sir!!!!

This is my first bridge. So coming from someone with much more experience than me for sure, that really means a lot, thank you.

Thanks to everyone for their kind words and support.

Hoping to get some decking done this weekend!

 

[deezler]

One comment I got my on my own smaller phone-pole bridge a couple times, was that I should have covered the top of the poles with waterproofing, under the decking. Ideally metal flashing, since tar paper breaks down pretty quick and then holds water. Any plans in that regard? I would think it perhaps a bit more important in your case since you cut open the poles to mill them flat across their top surfaces.

What are you using for decking anchors? I think I used 5" GRK structural screws on mine. You could probably get away with 4" screws... Like these:

GRK Fasteners 5/16 in. x 4 in. Star Drive Round Head Rugged Structural Wood Screw (45-Piece per-Pack) 112225 - The Home Depot

Make use of this GRK Fasteners Rugged Structural Screw to sharp threads and point bite instantly into material or reduce the splitting effects.

www.homedepot.com

 

[gable74]

One comment I got my on my own smaller phone-pole bridge a couple times, was that I should have covered the top of the poles with waterproofing, under the decking. Ideally metal flashing, since tar paper breaks down pretty quick and then holds water. Any plans in that regard? I would think it perhaps a bit more important in your case since you cut open the poles to mill them flat across their top surfaces.

What are you using for decking anchors? I think I used 5" GRK structural screws on mine. You could probably get away with 4" screws... Like these:

GRK Fasteners 5/16 in. x 4 in. Star Drive Round Head Rugged Structural Wood Screw (45-Piece per-Pack) 112225 - The Home Depot

Make use of this GRK Fasteners Rugged Structural Screw to sharp threads and point bite instantly into material or reduce the splitting effects.

www.homedepot.com

Didn't think about flashing the tops of the posts. I did not see any examples of that when I was looking at other bridges in the area but I will look into it, thanks.

Funny thing about the deck fasteners, this is what I picked up

They are stout! Almost like putting in a 5/16 lag.

 

[kenmbz]

Keep the pictures coming. Looks fantastic so far.

 

[EddieWalker]

There is a special tape that some people use to flash deck joists. I'm not a fan of metal or paper flashing the tops of joists because it's hit or miss on how well it works. While it does shed some of the water that comes from rain, it also retains moisture that is formed from condensation. That moisture remains under the flashing longer because it's protected from the flashing. The tape is supposed to help this because it's attached completely to the joist. On my jobs, I do not flash the tops of my joists.