Author Topic: bridge project (Read 1891 times)

backwoods sawyer · « **on:** November 06, 2014, 03:55:45 PM »

Been clearing a 2 mile long road thru BLM land and have to cross a year round fish creek twice.

The good news is I can get away with a 16' at one crossing 28' at the other. The alternitive was a 50' river crossing.

These bridges will need to handle a loaded log truck from time to time as the sawmill site will be at the end of the road and is the reason the road is being built.

My question is how big and how many Doug fir logs will I need for stingers, I can source large logs localy, or is this to much weight for that span.

Jim_Rogers · « **Reply #1 on:** November 06, 2014, 08:04:21 PM »

On the 16' bridge is the whole log truck, that is both front axle and rear axles going to be on the bridge at one time?
If so what is the gross weight of the truck?
You may have to make one of those "bridge mat" type thing where you bolt together large timbers 3' or 4' wide just enough for each wheel path to cross on.

Jim Rogers

giant splinter · « **Reply #2 on:** November 06, 2014, 11:55:33 PM »

With five rails from 24" Doug-Fir .... two opposite sides slabbed to about an 8" to 12" wide bearing surface for the deck and abutment tie in ( mark crown first ) and allow for a 48" to 60" of abutment bearing on solid ground or placed on dry stacked boulders with a minimum of 30" of flat load bearing surfaces you will be able to support well over 54,000# live/dynamic load using full 3" thick decking. with a 16' span and 5 to 7 axel rigs there will be more than ample weight bearing capability provided none of the axels are over 22,000# individually. Image 4943 in my gallery is a 44,000# truck bridge it is a five rail structure that spans 20' and has a 10' wide deck that rests on a heavy dry layed stone abutments, Jim Rogers helped in the design. A 28' span is not much different if the BLM will let you shore up the center of the span.

BCsaw · « **Reply #3 on:** November 07, 2014, 09:06:05 PM »

On one bridge that we constructed, we used poplar for the main supports crossing the creek. They ranged from 14 to 18" in diameter. The span was about 14', give or take. They were laid tight to each other and wrapped with cable around the bunch at each end to keep them from spreading. We then use spruce perpendicular to the poplar, side by side, and nailed to the poplar with spikes. We covered it with gravel and has been in use for over 20 years. We hauled across it every year with logging trucks weighing just shy of 70000kgs (150000 lbs approx.).

beenthere · « **Reply #4 on:** November 07, 2014, 09:32:36 PM »

BC
When/how will you be able to tell it is going to fail (or not) on the next load?

BCsaw · « **Reply #5 on:** November 08, 2014, 11:04:32 AM »

I would not haul across it anymore!

That would asking for trouble!!

It was made as temporary bridge, 5 years was the goal. We had to build it in a hurry as the old one washed out.

beenthere · « **Reply #6 on:** November 08, 2014, 12:28:16 PM »

Quote

I would not haul across it anymore!

When will you know (be able to tell) that that time has come? Or is it worth the risk of falling through with a load to keep using it?

Peter Drouin · « **Reply #7 on:** November 09, 2014, 07:39:33 AM »

I just use 8"x10"x16' and 2" planks

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