Yep, the bridge took a while to print. Months.

Like Bob said, in CAD you draw your item the size you want it to be in the real world, but you can scale anything up or down too. If you draw something big like a Sherman tank in full scale then scale it down to 1/16 scale for printing, you can get some scaling issues, but those have more to do with the limitations of the printer than the limitations of the CAD. You can scale every measurement of the real tank down to 1/16th, but that is a lot of work. Better to draw it as the real measurements, then scale down the whole thing at once.