Awesome, I need to make one just like this. Only, I would worry about the strength with just two main logs as your beams. I personally would have doubled it up, with at least 4 main log beams. Notice how the "other bridges around here" pic you put up has many, many beams. You just can't trust a tree log to last as the primary support, in my opinion. (note, this is far from a professional opinion). If you are only driving 4-wheelers across, of course no worries. But that L45 with attachments, or a full bucket load of material? Maybe safe now, but in 5 years I would be getting nervous.
In any case, looks like good work and many thanks for sharing! Any more pics of the support bases?