Tractor over trail Bridge?

stlbill · Feb 12, 2018

Hello,

Does anyone have any experience building a trail bridge to drive their sub-compact across?

I need to build a 5-6' wide bridge about 8-10' long over a 4' ditch. I was going to try 4 - 6"x6" timers on 18" centers. I am open to putting a vertical support in the middle if necessary.

The other option is a pipe, but I think a pipe will detract more from the scenic nature of my trail.

The tractor is a Deere 2305. In the TLB configuration I believe it weighs about 3,000 pounds. I figure another 1,000 pounds for operator and whatever I have in the bucket.

Thoughts?

Thank you in advance!

Bill

fried1765 · Feb 12, 2018

stlbill said:
Hello,

Does anyone have any experience building a trail bridge to drive their sub-compact across?

I need to build a 5-6' wide bridge about 8-10' long over a 4' ditch. I was going to try 4 - 6"x6" timers on 18" centers. I am open to putting a vertical support in the middle if necessary.

The other option is a pipe, but I think a pipe will detract more from the scenic nature of my trail.

The tractor is a Deere 2305. In the TLB configuration I believe it weighs about 3,000 pounds. I figure another 1,000 pounds for operator and whatever I have in the bucket.

Thoughts?

Thank you in advance!

Bill

I would absolutely recommend against using "timers" for building a bridge!
Sorry Bill: just couldn't help myself!

fried1765 · Feb 12, 2018

stlbill said:
Hello,

Does anyone have any experience building a trail bridge to drive their sub-compact across?

I need to build a 5-6' wide bridge about 8-10' long over a 4' ditch. I was going to try 4 - 6"x6" timers on 18" centers. I am open to putting a vertical support in the middle if necessary.

The other option is a pipe, but I think a pipe will detract more from the scenic nature of my trail.

The tractor is a Deere 2305. In the TLB configuration I believe it weighs about 3,000 pounds. I figure another 1,000 pounds for operator and whatever I have in the bucket.

Thoughts?

Thank you in advance!

Bill

Now: To be serious!

I would NOT use 4 - 6x6 timbers!
I would suggest that you use 8 - 2x12's, (or 2x14's, if you can get them).
Spike 2 - 2x12's together to form 4 - 4x12 beams, and space those 4 beams 18"OC.
I would suggest using PT Southern Yellow Pine lumber.
The reason for 2x12's is that you get increased strength from the depth of the beam, not the mass.
I note that in your in your weight estimate, you have omitted the quite significant dead load of the beams themselves, and the associated decking.

dickfoster · Feb 12, 2018

Does This Bridge Could Hold Even It's Own Weight? - YouTube.
Maybe just string up a couple of cables.

jmc · Feb 12, 2018

I think all your load will only be on the outside two timbers. Also, you will not regret making it a couple of feet wider than your tractor, this one or a future one. Or a trailer.

My neighbor built a longer span using two recycled telephone poles. His horses will not cross it but his Nissan will.

4570Man · Feb 12, 2018

I’d build it way heavier than necessary. 3 6x6s might hold it now. What about in 10 years when the timbers have had better days?

Creamer · Feb 12, 2018

Totally agree with Fried1765 - 2 2x12s glued and screwed together make a nice bean and is much stronger than needed but that allows for degradation and future uses. I would also build it 8' wide and space the beams underneath the loads, i.e two sets of beams about 18" apart centered under the tire treads. The middle of the bridge will never see much load. I would also put a couple of cross braces between the beams to help hold them straight.

ovrszd · Feb 12, 2018

I built a 20' long bridge last year. I've crossed it several times with my 7K lb Super Duty. I haven't had my 11K Kubota on it. Yet.

I used steel I-beams. Sorry I can't help you with your wood beam construction. Something about that just unnerves me.

JB13502 · Feb 12, 2018

dickfoster said:
Does This Bridge Could Hold Even It's Own Weight? - YouTube.
Maybe just string up a couple of cables.

Holy cow! Im not sure if that takes big brass ones or little common sense. Talk about pucker factor!

ovrszd · Feb 12, 2018

It's a cable bridge. Thousands of them in use in 3rd world countries. Yes,,,, requires big ones due to no side rails. I think that's what the discussion was in the beginning.

ktm250rider · Feb 12, 2018

Problem with wood is it will rot. Ive been building crossings with rocks by creating a natural culvert. If you access to a pipe, id use that and line both sides with rocks to keep the wild look.

ovrszd · Feb 12, 2018

ktm250rider said:
Problem with wood is it will rot. Ive been building crossings with rocks by creating a natural culvert. If you access to a pipe, id use that and line both sides with rocks to keep the wild look.

I agree. There's a lot more to building a bridge than the bridge itself. You gotta set it on something solid. Dirt banks don't count.

fried1765 · Feb 12, 2018

ovrszd said:
I built a 20' long bridge last year. I've crossed it several times with my 7K lb Super Duty. I haven't had my 11K Kubota on it. Yet.

I used steel I-beams. Sorry I can't help you with your wood beam construction. Something about that just unnerves me.

View attachment 539686

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More than a few 200 year old ALL WOOD covered bridges throughout the Northeast, STILL in everyday use.

fried1765 · Feb 12, 2018

fried1765 said:
More than a few ALL WOOD covered bridges throughout New England, STILL in everyday use.

That Ford looks mighty purdy sitting on your bridge!

KennyG · Feb 12, 2018

OK, I think I have completed your project. I built a bridge to span about 10 feet and it handles my 2320 with plenty of margin. Check it out.

http://www.tractorbynet.com/forums/projects/289644-my-bridge.html?highlight=bridge

fried1765 · Feb 12, 2018

KennyG said:
OK, I think I have completed your project. I built a bridge to span about 10 feet and it handles my 2320 with plenty of margin. Check it out.

http://www.tractorbynet.com/forums/projects/289644-my-bridge.html?highlight=bridge

You did an EXCELLENT job on your bridge !!!!

ovrszd · Feb 12, 2018

fried1765 said:
More than a few 200 year old ALL WOOD covered bridges throughout the Northeast, STILL in everyday use.

No doubt. Just wouldn't be my goal for material.

I actually think as small as this crossing is I'd do a culvert or low water crossing.

4570Man · Feb 12, 2018

If you’ve got a salvage yard close by you can probably get some steel beams for a comparable cost of wood beams. Seaton enterprise is my steel source and it’s 25 cents a pound which includes nearly anything else you’re likely to find.

MotorSeven · Feb 13, 2018

All you need to do is find a beat up 20' equipment type trailer or a truck bed. They can be had for much less than buying steel and building it. If there is any danger of abutment wash out, I would use those concrete 'pigs' that most concrete company's sell, they are 2'x2'x6' long and here they are $50 ea. So dig down a bit, lay some gravel if needed, then two pigs end to end on each side of the creek. Then winch the trailer bed across & set it on the pig abutments, then remove the tires or axles.....done.

I did one out of a 20' steel truck bed, and we just had a nice flood(as usual during winter) and the bridge stayed high and dry). I'll snap some pictures late today for you.

Hey OVRSZD....excellent job or your bridge:thumbsup:

rd_macgregor · Feb 13, 2018

In your (OP) case, I think I'd go with a culvert, unless the location experiences pretty extreme flow events.
I have an aging wooden bridge that needs to be replaced (if mushrooms growing out of the decking and support beams is any indication). My first choice was a flat-deck shipping container, but they are pretty rare...I'm now thinking of having a local trailer fabricator price out a heavy trailer deck (without tongue, springs, axles, wiring, etc.) as an alternative.