Tractor over trail Bridge?

[stlbill]

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]

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]

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]

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

 

[jmc]

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]

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]

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]

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]

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]

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.