davedj1
Veteran Member
I've driven my truck (5500 lb or so) over a bridge many times made up of two telephone poles with decking. There is a process known as glu-lams where they glue boards together to make very strong beams, some are found in churches, indoor pools etc. You could always go to your local lumber yard and have them give you the specs for your beam. Or find an engineer willing to divulge that info.
glulam beam - Google Search
glulam beam - Google Search