My attempt at making a bridge, hope you like the tutorial.
Nice. Not exactly the cleanest modeling in the world, but a good basic tutorial nonetheless.
My goal is to make these as quick and useful as possible. I hate when tutorial-makers spend too much time on smaller details. 
I want people to make better looking renders than I made, I think people enjoy improving things themselves.
When you enable proportional editing, you should make sure to indicate that it should be set to smooth type. Anyone who has it set differently will get different results.
I will pay attention to that the next time, thanks. I think most people will figure it out on their own in this tutorial. 