also, if you are working with a mechanic that deals with halves, round up if the number comes to .5. this is the only thing i have ever seen round down.
the physics for the bridges were great, what needs a little work is the physics of the objects. ex: i had a safe go against the force of gravity and the worker walked through it.
 "Dangerous adventure"){kind=icon}
 "Musaic Box"){kind=icon}
 "Cargo Bridge"){kind=icon}