This model had a troubled evolution. I had the Challenge verbally repeated to me - girder frames with a maximum of 113 parts, or so I heard. The resulting model is shown at bottom right. There is a bevel gear arrangement to turn the bridge. There are barriers and bracing. Also there are no plates used.
On looking at SELMEC News it was a shock to find the part count includes fixings. This model has about 100 parts too many.
It was time for a drastic part reduction. The bracing and the barriers went and other parts of the structure were simplified. There were still too many parts, so the bevel gear arrangement also had to go. The final models is shown top right.