Hi Chris - Happy to help in any way I can.
Your skp doesn't suggest, but I take it your trusses are longer than the span , and the braces (bridgespeak – struts in TF-speak) fall over the the bed timbers that sit on the abutments? This is traditional and good design, keeping the portals and their gables and thereby the weather well away from the bridges underpinnings. Also gives you a direct load path for the moment imparted by the braces.
Don't see any relish, Bottom Chord beyond the posts, King beyond the Bottom Chord. Good bridge design is all about relish and airspace / airflow.
How will the Floorbeams interact with the Chords? I'd think four can be made to suffice, one either side of the King and one at either end, these carrying four longitudinal sleepers and those some maybe 2 ½” flooring. (More bridgespeak – It's a floor not a deck) Best to avoid running the flooring over the Chords, it inhibits airflow and the ability to clean dirt and cobwebs away and makes it harder to visually inspect them with regularity.
How will your Ties and Upper Lateral bracing be configured?
I'd think the Shear Blocks might be overkill for such a short span, (you'll have the posts and the braces double-dapping & keying the Chord Lams) but it's a traditional solution and a good one – Bottom Chord scarfs are the first thing I look for when I walk into a new to me bridge. I'm a student of Chord splices, but it's also the first outward manifestation of the bridge geek in me.
Think airspace betwixt the Chord Lams !!!
We've long sourced traditional hardware (squarehead bolts, cast ogee washers etc.) from KL Jack in Manchester and Portland, But here's a source for some out there on the WC -
http://www.portlandbolt.com/projectresume/coveredbridgeprojects.htmlThe approach to cutting is a little different in bridgework. The forces and loads are constant, and crush is an issue not typical of most framing.
I'm gonna send you a PDF of a 60' ped bridge I designed, it's more truss than you need, but it's a good visual of how the various systems interact and that I think, will help as you design this one.