Another Bridge Thread

[tennesseejb]

Luke, I have pulled a couple trailers back there behind my quad, and I did take my truck back there a few times early on, but may need to clear a little on the path to get it back there again. I would plan on pulling the lumber on a trailer, either behind the tractor or my truck, even if I had to make a few runs. Is that what you are talking about, or do you have another idea?

 

[bigdeano]

You should be able to find info online how to make concrete beams. I built a house with tip up concrete panels I cast in the yard. I found the info on how much rebar, thickness, etc in the building code book. Was an interesting project.

Could you cast them on level ground where a cement truck can reach and then drag them with a vehicle?

 

[tennesseejb]

I'd be hesitant to do that. The trail to the creek is about 1/2 mile and includes some muddy and some rocky areas....

 

[KennyG]

The beams could be evenly spaced. The 2x decking will distribute the load. An alternative would be to double or closer space under the wheel path. That would add a little strength margin. There is no real need to double the beams, as long as you block them, as I said earlier.

As an engineer, I would hesitate to use cast concrete beams, unless you had assistance from someone experienced. I wouldn't do it on my own. The problem is that beams by nature get strength partly from tensile stress and concrete has poor tensile strength and is subject to sudden fracture. The reinforcing adds the tensile stress but it's placement is critical. No offense to bigdeano but the reinforcement placement and concrete cure process seems to be much more critical for a beam than a wall panel. I like wood because it's so forgiving and balanced in compressive and tensile strength. Just my personal thoughts.

 

[ovrszd]

For the kind of money you seem willing to spend, why don't you look for a flatbed off a truck? Pour your piers, drag it on, push dirt up against each end, done, bridge.....

 

[tungularafishcamp]

I have one of those 500$ cement mixers that are 3 pt mounted. Not the best built unit and only does half a yard at a time but it is a whole lot easier than by hand, just back up to your sand gravel pile throw in a few 5 gal buckets a bucket of cement squirt a little water mixing it while you drive to the dump site back right up n dump. It has held up for the foundation of a 28x50' building and lotsa other small jobs over the last 4 years or so. I have the blessing of all the free sand and gravel I could ever want and no chance of ever getting a cement truck here so it was an ez fix for me.

 

[teg]

I have pulled a couple trailers back there... ...or do you have another idea?

He might be thinking of using a 16 foot trailer as a bridge... (just guessing).

 

[Trials]

You really should price out 2 short lengths of large diameter culvert before you invest a whole bunch of money in P.T. wood. Culverts have the arch shape needed to transfer heavy weight more effectively then a straight span, and they will outlive you. For backfill you can use natural available rock material. They also roll real easy, so you can get them back into the woods with no problem. Plastic and steel are almost the same price, the plastic is a little nicer to work with imho. I think you might be pleasantly pleased with the cost once you have priced out the total construction cost using P.T. wood, fasteners and concrete.

 

[RedNeckRacin]

I've found a number of great threads on bridges. I've been thinking of a way to build one that just seems very simple, so I'm wondering of there is an aspect or risk I'm not considering. We have a creek near the back of our property that I'd like to be able to get an ATV and tractor across. The span of the creek is about 10 feet and the creek does not rise above the bank (in this spot) when it rains.

It would be difficult at this point to drag a trailer back there to span the creek and single pieces of culvert that wide are pretty pricy. That's not mentioning that I really just like the idea of wood.

What I'm considering is this: Pour concrete pads on both sides of the creek. Then lamniate 2x lumber across the entire width of the bridge. I realize that I could just laminate some beams and then lay a decking across them, so part of what I'm asking is whether there is a structural reason that is better than just running 14 or 16 foot lumber across and gluing/nailing/bolting it all together until it's 8 ft wide. At 1.5" each, that would mean 64 boards... at roughly $15/ea for 2x8x16 or $19/ea for 2x10x16, I'd essentially have a 8 or 10" x 8' slab of wood across the creek, which has me in it for lumber at $1000 - $1250. Seems it would be very simple to construct.

What say the group?

I think you can buy culvert pipe for alot cheaper than your cost estimate. I just bought some 15" hdpe pipe thus summer for about 140 for a 20' stick.

 

[newbury]

Luke, I have pulled a couple trailers back there behind my quad, and I did take my truck back there a few times early on, but may need to clear a little on the path to get it back there again. I would plan on pulling the lumber on a trailer, either behind the tractor or my truck, even if I had to make a few runs. Is that what you are talking about, or do you have another idea?

If you can drag a trailer behind your truck just use a trailer.
If the span of the creek is only 10' you should be able to buy an old equipment trailer with bald tires for well less than $1500 and drag it back there. I frequently see CL listings for equipment trailers that need tires going for around $1,200 in NE Mississippi and Memphis.