Bridge Lumber

[sdavies2000]

I'm in the process of building trails on my property and need to build a 30' bridge across a creek. It's going to be a long bridge with sills buried at each end and stringer logs spanning the creek. I have ash, cedar, aspen and maple available on my property. My first thought was to use cedar for everything but then I got reading and read somewhere you want your stringers to be hardwood. what does everyone think? the sills will definitely be cedar but what should the stringers be?

 

[mikester]

Option 1. Get a culvert and cover with dirt
Option 2. Buy a used flatbed tractor trailer deck and use that in your design.

Do yourself a favour, if you have to ask these questions then you shouldnt be designing that bridge. You will also need to talk to your local building inspector and/or roads superintendent if you are connecting to a public roadway.

You are in Ontario which means you need a professional engineer to design that custom made bridge for you.

 

[Clintock]

A span that long.. I’d buy an old trailer and take all axles and springs off. Drag across creek and level. Don’t have to worry about it floating away either if the water gets high.

 

[sdavies2000]

It’s 200yds behind my house in the bush, with nearly zero change in elevation. The banks are about 1.5’ above the creek bed. I’m not concerned with inspectors or engineers.

 

[sdavies2000]

It’s 200yds behind my house in the bush, with nearly zero change in elevation. The banks are about 1.5’ above the creek bed. I’m not concerned with inspectors or engineers.

I have considered a flat deck but it would be a bear to get back there

 

[Clintock]

I have considered a flat deck but it would be a bear to get back there

Rather deal with a bear once than fight wolves over and over...

 

[EddieWalker]

I've never built a bridge. Where I live, all those wood species would rot out in a couple of years.

I watched a bear hunting video years ago where they built a bridge over a creek up on Canada that was kind of neat. They dragged some logs across the creek with four wheelers, and then smoothed the top of the logs with a chainsaw. Then nailed boards onto the logs. It was fast, cheap and effective. For just a trail bridge in the back of your land, something like that seems ideal.

 

[Diggin It]

It’s 200yds behind my house in the bush, with nearly zero change in elevation. The banks are about 1.5’ above the creek bed.

How much current/flow is there? Does it flood higher than that? Rush faster after a heavy rain? What drives over it?

Can you consider some large diameter rock ... rip rap type stuff that will allow the flow? Think of a wet bridge type of thing where you drive over the rocks.

You might even be able to lay timbers on the rock if you need a smoother surface.

 

[deezler]

30 feet across but only 1.5' deep below the banks? Pics would help.

Does it flood out above the banks ever? Like, even once a decade ever?

 

[ROUSTABOUT]

Buy some big pipe or I beam. 30' too far for wood. Unless you pour some bannisters under it. When it breaks one day, only one side will, and someone you know will be upside down in the water with a machine on top of them. Build something good to stay.