Bridge Load Verification for Heavy Trucks

I have a small stream to cross and the DEM engineer recommended a bin block bridge. I drew up the design, but need to verify the materials will carry the weight of a fire truck. The bridge is 16' free span using 20' 12x65 (4 of) with a timber deck of 4x12 runners and 8x8 cross members. I just need to make sure it will carry the load of at least 7,500 pounds