truck bridge

[june]

hey guys i want to built a hemlock bridge on my land a full tractor trailer must be able to roll on it. so i am guessing dont go under 80000 pound working loag capacity? i was wondering if someone ad some knoledge on that or picts or a nice web site to refere to. o yeah the bridge neads to be 16  -18 feet long . thanks any comment will be apreciated

[lxskllr]

Not sure. I've probably laid out a few dozen professional bridges, but never done them as an amateur. The most important thing is probably the abutments. They need to be solid to hold your deck and embankments up. That's a lot of weight you need to carry. I think I could put something together to hold a tractor or a car, but I wouldn't be comfortable designing for a loaded truck. That's a lot of liability if the bridge doesn't hold up.

[june]

yes i agree !!

[TKehl]

Not saying wood wouldn't work.  But if it were mine, I wouldn't build with anything less than concrete and steel for that span.  If it holds now, how long will it hold up?  What happens if it gives?

We have a shorter span for a creek at the house we are renovating.  Has just been forded for as long as there has been a house there.  We looked into bridge spans, and haven't totally ruled them out, but the question we ran into is, "Will the fire department cross a homemade bridge with a pumper truck?" 

We will either, 1.  make it a low water concrete crossing (vented ford) or 2. build a bridge, but have secondary access for heavy trucks.

[landscraper]

Google USFS Timber Bridge Manual - 1992.   Lots of good info there to get you started.

[june]

yeah thx

[mike_belben]

Is it possible to:

*hide a pair of steel I beams underneath to give the appearance of a wooden only bridge?  


*cut the unsupported span down by using large angled knee braces, or a vertical piling in the center?  Even mafia blocks stacked in the middle of the creek or gap youre crossing?  

[barbender]

I've gotta ask, I've heard you New England guys refer to the big cast concrete blocks as "mafia blocks". Is that because they are big enough to hide a body in?😲😁

[Dave Shepard]

Cement shoes - Wikipedia

[mike_belben]

I think thats just what their called up there.  Jersey barrier is the only other name ive ever heard but theyre a different shape.

I think the name comes from new yorks history with mafia monopolizing concrete services to control the price.  Well where do blocks come from?  Batch plant leftovers going into the block forms at the end of the day.  Hence, mafia block.

[snowstorm]

a loaded trailer will be over 100,000 lbs. find one thats been in place for a while. to see how it was built. gonna need a lot of steel in it. or a big culvert. that would be the cheapest way 

[Stephen]

You only have one set of axles on the bridge at a time, so weight is actually less than the full load.

[Grizzly]

I think your allowed more weight provincially than some of us other provinces but I'm not certain what local laws are. I ran legal for all other jurisdictions and I believe I was light for Quebec (I hauled in 10 provinces as well as lower 48 states). So assuming minimum of 5500kgs for steering on 11in tires and 17,000kgs for tandem drives would make for max weight on bridge at one time (see above reminder) of 49,590lbs. I've been over temporary timber bridges with a log truck over longer spans so it can be done. But I'm not the engineer to know how. I just drove over them. Heaviest load I took over the river on temp bridge was about 150,000lbs on 5 axles. I was nervous on first pass but don't tell anyone.

[june]

hey guys i guess after reading all of your post i wille buy an old trailler and pit the plasma cutter in it it will probably be the safest way thanks for all of your advice

[quilbilly]

You can build a bridge that'll take 100k+ out of wood no problem. We built one out of 40ft Glu lam beams with 3 inch decking. Took a 475 barko with a keto 1000 over it no problem. Hauled dozens of loads over it. Another idea is to take some decent size logs and put decking over them, lots of guys out here will do that for a temp bridge.

[snowstorm]

You can build a bridge that'll take 100k+ out of wood no problem. We built one out of 40ft Glu lam beams with 3 inch decking. Took a 475 barko with a keto 1000 over it no problem. Hauled dozens of loads over it. Another idea is to take some decent size logs and put decking over them, lots of guys out here will do that for a temp bridge.

that keto 1000 is a big boy. i have a 500

[june]

nice what was your distance of the bridge( span) ? what was the essence  of the timber and how wide were your beam by how high. and were they laminated

thanks

[Don P]

These are glulam floor load tables but there is quite a bit of info on their site;
http://www.aitc-glulam.org/capacity.asp

Someone mentioned above about halving the load because only one set of wheels is on the deck at a time. And then, I'd double a rolling load.

Old flatbed trailers or railcars is going to be the best solution I'd bet.

[Southside]

Maybe call a few logging contractors and see if anyone has a skidder bridge sitting in the brush they are willing to sell. 

[quilbilly]

Forgot how big the beams were maybe 6x18 or so? Got em from a torn down warehouse in Tacoma. We had four and they spanned about 25 ft, we had large concrete blocks on both sides of the creek and built up to bridge with the dirt and gravel. Our loads were mostly 88k I believe the barko set up was over 100k though, pretty much the same size as a 235 cat I think.

[CX3]

Lay several 15 inch diameter oak trees side by side across there. Deck them with full 2 inch oak boards. We moved 100 loads across one. Worked great