Hello all, I am currently trying to figure out a cheap way to build a "bridge" that will go in my back yard. It will primarily be used to drive my 2000lb lawn mower over a small creek. I want to support it with 2 to beams at a 30 ft span as I will rest 2x8 or 2X10 pieces of wood on it. It will be flat and just have a small incline on each side to get on and off it. I need to figure out what beam size to use (preferably I-beam). Any formulas or any advice that applies to my situation helps a lot. Thank you in advance. I have also attached a sketch so you can visualize what I am discussing.