file and video Link_ex3

The Link down below is the final sketch up file:
https://www.dropbox.com/s/d71me0v4puobrvz/final.skp?dl=0
The link down below is the animation that shows the bridge in details with moving element:
https://www.dropbox.com/s/8c9uk0ew4hihw56/final_animation.mp4?dl=0