I wanted the bridge to be able to hold itself together, so I had a simple truss layer below the bridge to allow it to spread the weight of the load. The design above the bridge is taken from bridge where the the focus is to hold the center up while still being able to hold other parts of the bridge and spreading the weight.
As for me, I noticed that all we are going to hold is a lot of weight at the centre point of the bridge, so why not make one with 2 points such that it distributes the weight to the rest of structure. With this, I deemed the program useless as I can't get it simulate my bridge.
I took inspiration from the K-Truss bridge, but it isn't able to work when it comes to simulation in the program. So I modified it to just be a simple criss-cross design, which is surprisingly stable when simulated.