A few friends and I have found an old access road here on Vancouver Island that may go through to some interesting spot according to our maps.

The problem is that a few kilometres up the road, there is a large ditch measuring about 12' deep by 10' across.

We'd like to build a bridge to drive across and could use some input from anyone who has done such. The trees in this area are mostly Alders and this is what we'd be using for construction.

Any tips and/or suggestion?

Thanks much,

Warren

 

I would get some railroad ties if at all possible you'll find them cheap and effective.

 

get a couple of generators, some hose, and a couple of pumps and drain it ...

 

do you have a couple sets of bridging ladders that you could link together and support from below, rather than constructing a permanent bridge?

-sean

 

The ditch is not driveable and there is no water in it. I don't want to build anything permanent (just enough to last a few seasons) and I'd prefer to use materials that would be easily found in the area and not haul anything up there other than saws, rope and maybe some large spikes.

Thanks for the feedback...

Warren

 

Many bridges have been built just by spanning the gap with large timbers or whole logs. If you don't have logs big enough, you'd have to anchor smaller ones together some way (like wrap steel cable around to strap them together) to create a surface for each set of wheels as a minimum. Another way is big logs spanning the gap with smaller ones from one log to the other to create a deck. Lacking large logs, look at how railroad trestles are built. Of course, you also have to worry about what your logs/timers are resting on to make sure it doesn't give way.

However, if you don't really know what you're doing, and don't want to study up a bit on building such things, you should probably forget the whole idea. Do you really want to experiment and have your rig, with you driving it, fall into that ditch because you guessed at how strong it needs to be and didn't get it quite right?

If you want to continue, the construction and building industry has span tables for wood timbers that would tell how large a timber needs to be to span distance x and support mass y for different species and grades of timber.

 

I say build a couple ramps and Evil Kenevil it!

 

i second that

 

my boss had to build a bridge for his drive way. it is maby 20-25 feet across and the hole suport system is made out of 12x8" beams and there is two suport posts. side view ----|----|----
| |
the suport posts are cemented in to a little pad because the bridge is over a stream and it is soft. the deck of the bridge is made of 8x6" boards. he has said several times that the 8x6 s are just for looks and a little extra width for driving on. he has had many heavy trucks (small flatbed semis with dual axeles and a load of lumber) go across is with no thought of any problems. the only thing he dosent let go across is cement and dump trucks. he is a house bulder/ general contractor so he knows his wood and load ratings. if it were me i would drop a few trees that are a good 15" in diameter. then lay two at each side of the tracks with 5-8' of overlap on to good salid ground on each end. i would also make some sort of deck on each side for the tires to ride on. brace it in the center and it should hold a lot more than you will put on it. it is only 10' asross

 

Cheers, thanks!

 

Wow, who's gonna be the first to test drive the bridge? Major white knuckler!

 

Whatever you do, make sure you take a video camera for the 1st test drive!

 

That'd most likely be me.

I'll be sure to video it!


Warren

 

The question to be asked is- who owns the land, and what laws might you be breaking by building the bridge?

 

Well, it's Crown land (provincial Gov't) and it's a de-activated logging road so it shouldn't be a problem.

 

well, it seemed to work ok...

 

that looks good, it is a shorter distance than i thought, i hope it holds for some time did it flex at all how did it look.

 

Yes. The logs are close to 17' each and we used two per side.

It didn't flex at all...probably because we braced the middles from underneath with a straight-up-and-down log.

I hope it lasts too; maybe get a year out of it before I stop trusting so much.




Warren

 

Solid looking!

It would keep people like me off the trail also, I wouldn't trust that thing with my rig unless I built it!

Was it worth the build? I hope the road after that is impressive enough.