ATV/Riding Mower bridge using materials laying around...request thoughts

   / ATV/Riding Mower bridge using materials laying around...request thoughts #13  
How is your pier attached to the underside of your beams?
Each pier is rebar pinned to the horizontal pole it’s under.

2x4 x brace between piers

2x4s horizontally between piers as well
 
   / ATV/Riding Mower bridge using materials laying around...request thoughts #14  
Have two simple bridges, both based on two 4x6x12 foot timbers with 2x6 inch cross decking... Actual free span is about 10 feet.... It supports a 520 pound riding mower and 200 pound operator just fine.... Think I would go bigger with main timbers before trying to cross with 1400 pound tractor though....
 
   / ATV/Riding Mower bridge using materials laying around...request thoughts #15  
I like doorman63's suggestion of utility poles. They'll support a lot of weight, and will likely outlast you before they rot, unlike the fir.
As far as center support (should you go that route), how big is the stream at its highest? A strong current or high level is going to put a lot of stress on those supports unless they're well anchored.
 
   / ATV/Riding Mower bridge using materials laying around...request thoughts #16  
I like doorman63's suggestion of utility poles. They'll support a lot of weight, and will likely outlast you before they rot, unlike the fir.
As far as center support (should you go that route), how big is the stream at its highest? A strong current or high level is going to put a lot of stress on those supports unless they're well anchored.
Yep. I'd also worry about debris lodging against the center support.
 
   / ATV/Riding Mower bridge using materials laying around...request thoughts #17  
Since you've already got your stringers, this may not help, but around here (VT) there are a lot of skidoo bridges built with old trailer frames or mobile home frames. Cheap, rot resistant and strong
 
   / ATV/Riding Mower bridge using materials laying around...request thoughts #18  
Yep. I'd also worry about debris lodging against the center support.
I just deal with the debris.
So far no “structural” issues

As far as bouncing…..
I’ve got another bridge-same length-approx 3’ wide just for foot traffic.
It’s is a bit bouncy……..I always comment to people……how many bridges do you have? 1675962412418.jpeg6995CFC5-749F-4509-9282-FAFA8A46D540.jpeg01301EF1-48B4-4DD8-A907-BC77F37B7929.jpeg
 
   / ATV/Riding Mower bridge using materials laying around...request thoughts
  • Thread Starter
#19  
Have two simple bridges, both based on two 4x6x12 foot timbers with 2x6 inch cross decking... Actual free span is about 10 feet.... It supports a 520 pound riding mower and 200 pound operator just fine.... Think I would go bigger with main timbers before trying to cross with 1400 pound tractor though....
Your bridge frame is about the specs of my beams (smaller beam is 5" on one end and 7" on the other, similar to a 4x6). Free span will be about 12'.
I am sure you used PT beams.

I am thinking of burning the outside and then putting a natural oil on the fir beams to help preserve them. Then, also add a pier or support in the middle (I understand the drawbacks) as the fir beams will lose strength due to not being pressure treated.

I have tried to find utility poles around here, but no luck.
 
   / ATV/Riding Mower bridge using materials laying around...request thoughts
  • Thread Starter
#20  
Since you've already got your stringers, this may not help, but around here (VT) there are a lot of skidoo bridges built with old trailer frames or mobile home frames. Cheap, rot resistant and strong
I have looked at the trailer route, and may do another bridge based around a trailer, but people around here want a mint for their junk. Part of the west coast extra cost tax I guess.
 
 
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